R-Squared Energy Blog

Pure Energy

Ford Awakens from a Slumber; Post Office Rejects Ethanol

It seems that the reality of our situation is sinking in at Ford:

Ford’s trouble: $4 gas is here to stay

NEW YORK (CNNMoney.com) — Ford Motor Co. executives say they believe that $4 gas is here to stay, resulting in a fundamental consumer shift away from gas-guzzling SUVs and pickups and causing continued losses at its core North American auto unit.

The company said it expects gas prices to remain in the range of $3.75 to $4.25 a gallon through the end of 2009. And that expectation prompted the nation’s No. 3 automaker to announce deep production cuts for what has been its best selling and most profitable vehicles for several decades and could lead to more plant closings and job cuts down the road.

The company plans to ramp up production of smaller cars and crossovers: Ford Focus, Fusion, Edge and Escape, the Mercury Milan and Mariner, as well as the Lincoln MKZ and Lincoln MKX. These models generally cost less and have lower profit margins than the light truck models for which Ford is cutting production, such as the F-Series pickup, still the nation’s best selling vehicle.

I think that’s good news for everyone, except Ford shareholders and some Ford employees.

And a feel-good story about the ethanol industry:

Ethanol Vehicles for Post Office Burn More Gas, Get Fewer Miles

May 21 (Bloomberg) — The U.S. Postal Service purchased more than 30,000 ethanol-capable trucks and minivans from 1999 to 2005, making it the biggest American buyer of alternative-fuel vehicles. Gasoline consumption jumped by more than 1.5 million gallons as a result.

The trucks, derived from Ford Motor Co.’s Explorer sport-utility vehicle, had bigger engines than Jeeps from the former Chrysler Corp. they replaced. A Postal Service study found the new vehicles got as much as 29 percent fewer miles to the gallon. Mail carriers used the corn-based fuel in just 1,000 of them because there weren’t enough places to buy it.

“You’re getting fewer miles per gallon, and it’s costing us more,” Walt O’Tormey, the Postal Service’s Washington-based vice president of engineering, said in an interview. The agency may buy electric vehicles instead, he said.

Perhaps I should have said, “feel-good story for me.” After all, when corn-fueled cars are traded in for electric cars, that feels pretty good to me. In fairness though, I should point out that it does say that the ethanol-fueled vehicles they bought had bigger engines. Not sure why they went that route.

May 22, 2008 Posted by | auto industry, electric cars, ethanol, Ford, fuel efficiency | 7 Comments

Nissan Enters the Electric Arena

I am feeling more and more optimistic that we are going to soon have a decent choice of viable plug-in hybrids (PHEVs). Nissan has now announced that they will have an offering in the U.S. and Japan by 2010:

Nissan plans electric car in U.S. and Japan by 2010

Nissan Motor plans to sell an electric car in the United States and Japan by 2010, raising the stakes in the race to develop environmentally friendly vehicles.

The commitment – announced Tuesday by Nissan’s chief executive, Carlos Ghosn – will be the first by a major automaker to bring a zero-emission vehicle to the American market. Nissan also expects to sell a lineup of electric vehicles globally by 2012.

In an interview Monday, Ghosn said Nissan decided to accelerate development of battery-powered vehicles because of high gasoline prices and environmental concerns, not just because of the need to meet stricter fuel-economy standards.

“What we are seeing is that the shifts coming from the markets are more powerful than what regulators are doing,” he said.

This marks a dramatic about-face for Ghosn, who had downplayed the idea just a few years ago:

In a 2005 speech to the National Automobile Dealers Association, he called gas-electric hybrids “niche products” useful only to meet strict fuel-economy and emission standards in states like California.

“It wasn’t long ago that Carlos Ghosn was a big naysayer about the role of electric vehicles,” said John O’Dell, senior editor at the auto Web site GreenCarAdvisor.com. “Obviously, something has opened his eyes.”

They have their sights set high:

Nissan, which a decade ago was on the brink of bankruptcy, is the first manufacturer to say it will sell mass-market all-electric vehicles worldwide. The zero emissions refers to those from the car’s tailpipe and not those from the production of electricity used to power the car.

Still, O’Dell said: “Nissan is upping the ante tremendously. They are the first to put it on the line and say we’re going to have an all-electric vehicle for a certain market by a certain date.”

Good stuff. Keep ’em coming. For my next calculation, I need to see how much power I could generate by putting a solar panel on the roof of my electric car and letting it recharge all day…

May 14, 2008 Posted by | electric cars, Nissan, phev | 53 Comments

Replacing Gasoline with Solar Power

Executive Summary

If you don’t want to run through the calculations, here is the summary. I attempted a thought experiment in which I calculated whether it would be feasible to use solar power to generate enough energy to offset all U.S. gasoline consumption. My conclusion is that it will take about 444,000 megawatts of electrical generating capacity. Current U.S. generating capacity is over 900,000 megawatts, but there isn’t a whole lot of spare capacity in that number.

To generate 444,000 megawatts with solar PV would require just under 1,300 square miles (a 36 mile by 36 mile square) of just PV surface area. To generate that much power with solar thermal – including supporting infrastructure – would require 4,719 square miles (a 69 mile by 69 mile square). A large area, but not impossible to envision us eventually achieving this.

——————–

Introduction

Having made an attempt to calculate the number of square miles to replace current U.S. electricity consumption via solar PV or solar thermal, I have been challenged to do the same exercise for replacing our gasoline usage. (In fact, I was told by someone that they had never seen this kind of calculation done, so I told them I would do it). I have no idea how this calculation is going to turn out, but I suspect it is going to be similar to the previous calculation for replacing electrical consumption. My guess is less than 100 miles by 100 miles. Note that this is a thought experiment, in which I try to get an idea of what it would take to achieve this.

First, some caveats. There are still technical obstacles that prevent this scenario from being realized. Those are, 1). Battery range is still too low (The plug-in Prius is only going to be able to go 7 miles on battery power).; and 2). Solar power can’t be adequately stored. However, that’s not the purpose of the exercise. The purpose is to satisfy my curiosity: If we were going to try to replace gasoline with solar power, are the land requirements prohibitive?

I am only going to do this calculation for gasoline, as I think it is unlikely that electricity will ever power long-haul trucks or airplanes.

How Much Do We Need?

The U.S. currently consumes 389 million gallons of gasoline per day. (Source: EIA). A gallon of gasoline contains about 115,000 BTUs. (Source: EPA). The energy content of this is equivalent to 45 trillion BTUs per day. The average efficiency of an internal combustion engine (ICE) – that is the percentage of those BTUs that actually go into moving the vehicle down the road – is about 15%. (Source: DOE). Therefore, the energy that goes toward actually moving the vehicles is 6.7 trillion BTUs per day.

The efficiency of electric infrastructure can be broken down into several steps. According to this source, the respective efficiencies for the transmission lines, charging, and the vehicle efficiency are 95%, 88%, and 88%, for an overall efficiency (after the electricity is produced) of 74%. To replace the gasoline BTUs that go toward moving the vehicle with electricity is going to require 6.7 trillion/0.74, or 9.1 trillion BTUs. To convert to electricity, we use 3,413 BTUs/kilowatt-hour (kWh). Thus, 9.1 trillion BTUs/day is equal to 2.7 billion kWh/day. That’s how much energy we need. To convert this to power, we need to multiply by 1 day/24 hours, and that gives us 111 million kilowatts, or 111,000 megawatts (MW) of power generation required.

Looking back at my Solar Thought Experiment, I calculated 2,531 square miles to replace our peak electrical demand of 746,470 MW (746 GW). However, the current calculation is a different sort of calculation than what I did previously. The previous calculation attempted to have enough installed solar PV to meet peak demand. In the case of replacing our transportation fuel, I need enough panels to produce the required transportation energy in 8 hours or so while the sun is shining. To be conservative, we can assume 6 hours, which means we will actually need four times the 111,000 MW, or 444,000 MW.

Using Solar PV

From the previous essay, I used a conservative value of 12.5 watts per square foot as the generating capacity of an actual GE PV panel. To get 444,000 MW is going to take an area of 35.5 billion square feet, which is 1274 square miles. This is an area of just under 36 miles by 36 miles. However, this is just the surface area required to generate the electricity. It does not include area required for supporting infrastructure.

Using Solar Thermal

Doing the same calculation based on the solar thermal output from Running the U.S. on Solar Power, the expectation was that 0.147 megawatts could be produced per acre. This did include all of the land associated with infrastructure. If we use that number, we find that to generate 444,000 MW is going to take a little over 3 million acres, or 4,719 square miles. This is a square of just under 69 miles by 69 miles.

The reality is that we would use a combination of the solar PV and solar thermal. We have a lot of available rooftops that can create electricity with solar PV, and there are large tracts of land in sunny Arizona and Nevada that can create electricity with solar thermal.

Conclusions

Clearly, a lot of area is required, but it isn’t impossibly large. Of course to achieve this, a couple of big problems need to be resolved. First, battery life needs to improve somewhat before people are going to embrace electric transport. According to this ABC News story, the average commute is 16 miles one-way, but the range of the plug-in Prius is only expected to be 7 miles. The Aptera, on the other hand, claims a range of 120 miles. Maybe we just need to change the way we think about what we drive. (On the other hand, not a lot of commuters are going to climb into an Aptera if they have to share the road with large SUVs).

Second, and the bigger issue, is that we still don’t have a good way to store excess solar power. We need to have a good storage mechanism so electric cars can be charged at night from solar electricity produced during the day. One idea for this that I have seen floated is to use peak solar energy to electrolyze water, and then store the hydrogen in centralized locations. The hydrogen would then be burned at night to run centralized electrical generators. Not the most efficient method for storing solar energy, but technically workable.

Finally, the current electrical grid couldn’t handle such a large increase, but the model I envision would generate and consume the electricity locally.

Note

I had delayed posting this for almost a week, because I was sure there was an error in the calculations. I finally found one (I had turned a kilowatt into a watt), but let me know if you find other errors or incorrect assumptions.

May 12, 2008 Posted by | electric cars, electricity, electricity usage, solar power, solar PV, solar thermal | 107 Comments

The Aptera

Flying on the plane back to Amsterdam yesterday, I picked up a copy of Newsweek. Inside, there was a mention of a new vehicle that I had never heard of before, the Aptera:

10 Fixes For the Planet

7. The Aptera: A funky new hybrid-electric car gets 300 miles per gallon of gas.

The dirty secret of automakers, says Jib Ellison, CEO of BluSkye Sustainability Consulting, is that most of the energy used by a car comes from moving the vehicle itself, not the people in it. “That’s because cars aren’t designed to be as aerodynamic as they could be, and because we have this obsession with heavy vehicles, even though there are now lighter materials that are just as safe,” he says. But a prototype car from upstart Aptera Motors in Carlsbad, Calif., could help change all that.

The Aptera is not like any vehicle on the road today. It’s made with ultra-light (but superstrong) composites, and it has just three wheels to reduce its weight still further. It also has a funky shape—a cross between an insect and a flying saucer—that was designed in the computerized equivalent of a wind tunnel to minimize drag. By next year the car will be available in two models—one hybrid electric and the other purely electric, which can be plugged into any outlet—”even a solar carport,” says cofounder Steven Fambro.

Not that a $30,000 two-seater that requires eight hours of recharging will be everyone’s ideal car. But Fambro isn’t worried. He’s presold 1,300 Apteras without spending a dollar on advertising (although he’s selling only in California at first to minimize distribution and repair issues). “It’s selling itself,” he says. “And $100-a-barrel oil doesn’t hurt.” Are you listening, GM?

Anyway, I thought that was interesting. You can read more about it at the company website: http://www.aptera.com/

May 6, 2008 Posted by | Aptera, electric cars, fuel efficiency | 15 Comments

The Aptera

Flying on the plane back to Amsterdam yesterday, I picked up a copy of Newsweek. Inside, there was a mention of a new vehicle that I had never heard of before, the Aptera:

10 Fixes For the Planet

7. The Aptera: A funky new hybrid-electric car gets 300 miles per gallon of gas.

The dirty secret of automakers, says Jib Ellison, CEO of BluSkye Sustainability Consulting, is that most of the energy used by a car comes from moving the vehicle itself, not the people in it. “That’s because cars aren’t designed to be as aerodynamic as they could be, and because we have this obsession with heavy vehicles, even though there are now lighter materials that are just as safe,” he says. But a prototype car from upstart Aptera Motors in Carlsbad, Calif., could help change all that.

The Aptera is not like any vehicle on the road today. It’s made with ultra-light (but superstrong) composites, and it has just three wheels to reduce its weight still further. It also has a funky shape—a cross between an insect and a flying saucer—that was designed in the computerized equivalent of a wind tunnel to minimize drag. By next year the car will be available in two models—one hybrid electric and the other purely electric, which can be plugged into any outlet—”even a solar carport,” says cofounder Steven Fambro.

Not that a $30,000 two-seater that requires eight hours of recharging will be everyone’s ideal car. But Fambro isn’t worried. He’s presold 1,300 Apteras without spending a dollar on advertising (although he’s selling only in California at first to minimize distribution and repair issues). “It’s selling itself,” he says. “And $100-a-barrel oil doesn’t hurt.” Are you listening, GM?

Anyway, I thought that was interesting. You can read more about it at the company website: http://www.aptera.com/

May 6, 2008 Posted by | Aptera, electric cars, fuel efficiency | 15 Comments

Fuel from Air?

One thing we seem to have in limitless supply is gullibility. You may have seen the story sweeping through the energy circles of the Web:

Federal Lab Says It Can Harvest Fuel From Air

We love the painless technological solution. “This solves Global Warming AND produces carbon neutral fuel!” I talk to people all the time who say, in reference to our energy and environmental problems, “They will figure something out.” So along comes a story like this, and the layman reads the headlines and breathes a sigh of relief. We can make fuel from thin air. This must be even better than cars that run on water or cold fusion.

So what’s the deal? Here is an explanation from the linked article:

In the category of things that sound so good they have to be checked out more thoroughly (so stay tuned) is this news out of Los Alamos National Laboratory:

Scientists there say they have developed a way to produce truly carbon-neutral fuel and useful organic chemicals at large scale using water and carbon dioxide removed from the air as raw materials. There are plenty of schemes brewing to capture carbon dioxide, both directly from the atmosphere and from the stacks of power plants. All of them, for the moment, are costly or hard to envision at the billion-tons-a-year scale that would be needed to blunt the buildup of carbon dioxide in the atmosphere coming mainly from fuel burning.

I like to think I check things out thoroughly, and I try to approach things realistically. I consider myself to be a realistic optimist. It has nothing to do with being a naysayer, it is all about understanding basic science and engineering and knowing what’s likely, what isn’t, and what simply violates physical laws. So, is this pie-in-the-sky or a serious candidate for an energy solution?

Let’s take a critical look. First, details are sketchy (aren’t they always?). They are supposed to be released next week:

Details on the Los Alamos approach will come next week when Dr. Martin gives a presentation at a government and industry meeting, Alternative Energy Now, in Lake Buena Vista, Fla. The conference, held at a resort for military personnel, is sponsored mainly by the U.S. Air Force.

Let’s be perfectly clear. Could you produce fuel out of carbon dioxide and water? Sure you can – with massive energy inputs. You can’t get around the chemistry. When you burn something like natural gas, oil, coal, or just about anything organic – you get carbon dioxide and water. The amount of energy to turn it back into fuel is greater than the energy that was released in the first place. That is a fundamental law of thermodynamics.

As a simple illustrative example, let’s say I burned a quantity of natural gas and it released 10 BTUs per the following reaction: CH4 + 2 O2 = CO2 + 2 H20. Then to reverse that reaction is going to take more than 10 BTUs, and potentially a lot more. So where is this energy going to come from? Why, nuclear reactors of course:

This plan has a minor hurdle, too; the electricity for driving the chemical processes, according to a white paper describing the overarching concept, would come from nuclear power.

That’s more than a minor hurdle. If the fuel takes more energy to produce than it contains – and the laws of chemistry are against you in this case – then you have to ask whether there is a better use of that energy. If (for instance) I take 20 BTUs of nuclear energy to produce 10 BTUs of liquid fuel – was there a better end use for that nuclear energy? How about putting those 20 BTUs into an electric car, which has a much greater efficiency than an internal combustion engine? That is a much better net than the wasteful route of turning it into liquid fuel.

Make no mistake, technical feasibility is certainly there. Likewise, I can technically run a car off of water, or make fuel out of dirt. I could mine Titan for hydrocarbons. I could even build a colony on the moon or at the bottom of the ocean as a “solution” to overpopulation. These are things that one could technically do. That doesn’t mean any of them make sense.

That’s what I would say about this proposal. Unless they have figured out a way to violate the laws of chemistry, there is no free lunch. If you had vast quantities of cheap electricity, then sure, you could do it. But in that case why not just use the electricity directly?

Conclusion: The proponents have gotten way ahead of themselves, and I have yet to see anyone point out the basic fact regarding the energy balance: It will necessarily be a net consumer of energy, not an energy producer.

One other thing:

As described in a news release by Mr. Martin, it sounds like a possible candidate for Richard Branson’s $25 million carbon-capturing prize:

“Our concept enhances U.S. energy and material security by reducing dependence on imported oil. Initial system and economic analyses indicate that the prices of Green Freedom commodities would be either comparable to the current market or competitive with those of other carbon-neutral, alternative technologies currently being considered.”

First, you would be trading dependence on imported oil for dependence on imported uranium. Again, no free lunch. Second, I know someone else who has a much stronger case for Branson’s prize. 😉

April 16, 2008 Posted by | Argonne, carbon sequestration, electric cars, global warming, technology | 29 Comments

Electric Cars versus the ICE

Someone asked today at The Oil Drum about the primary reasons one would favor electric cars over the internal combustion engine (ICE). I responded

Yes. To me there are two big incentives. One is that electric motors are much more efficient than the ICE. Second is that electricity can come from such a large diversity of sources. Yes, it’s coal now. It can increasingly be solar, biomass gasification, nuclear, wind, geothermal, etc. There just aren’t too many liquid options, and different liquid fuels may require different engines.

But I decided to double-check the efficiency numbers, and came across the following link:

Debunking the Myth of EVs and Smokestacks

Now you know a love a good debunking, so I had a read. It’s a bit dated, but the information was still worthwhile. I ran across Table 4, shown below, which I thought was quite interesting:

EVs & Power Plants ICE & Fuel Refining
Processing 39% (Electricity Generation) 92% (Refining)
Transmission Lines 95%
Charging 88%
Vehicle Efficiency 88% 15%
Overall Efficiency 28% 14%

Table 4. Operating Efficiency Comparison Between EVs and ICE Vehicles

The bottom line is more or less what I expected, but the vehicle efficiency at 88% is higher than I would have guessed. Anyone with experience in that area? If the efficiency is correct (also note Tables 3 and 5), that provides a compelling argument for electric transport. Now we just need to get those darn batteries sorted. (The plug-in Prius is only going to be able to go 7 miles on battery power).

January 20, 2008 Posted by | electric cars, phev | 461 Comments

Review: How Can We Outlive Our Way of Life?

“Have the guts to consider the silent consequences when standing in front of the next snake-oil humanitarian.” Nassim Nicholas Taleb in The Black Swan

I believe our generation faces a sobering choice: Take serious steps to reduce our fossil fuel usage now – and this will undoubtedly entail some amount of hardship – or leave it to our children to face a great deal of hardship. I firmly believe this is our choice, and we must look to solutions that move us in that direction. I also believe that if most people understood that we are pushing a very serious problem onto our children – instead of assuming scientists and engineers will solve the problem – then we would collectively pursue a solution with far greater urgency.

Berkeley Professor Tad Patzek, who has written many articles that are critical of our present attempts to replace fossil fuels with biofuels, has just published a new article in which he also discusses solutions:

How Can We Outlive Our Way of Life? (PDF download)

Many of you know Tad Patzek as the co-author of a number of papers with David Pimentel. If you are pro corn-ethanol, then you have probably been conditioned to discount everything Professor Patzek writes. But even if you disagree with his corn ethanol position, there is still a lot to take away from this paper. Patzek’s conclusion on cellulosic ethanol is the same as my own: The status of cellulosic ethanol has been exaggerated and over-hyped, and the solution that we really ought to be pursuing is electric. The abstract of the paper reads:

In this paper I outline the rational, science-based arguments that question current wisdom of replacing fossil plant fuels (coal, oil and natural gas) with fresh plant agrofuels. This 1:1 replacement is absolutely impossible for more than a few years, because of the ways the planet Earth works and maintains life. After these few years, the denuded Earth will be a different planet, hostile to human life. I argue that with the current set of objective constraints a continuous stable solution to human life cannot exist in the near-future, unless we all rapidly implement much more limited ways of using the Earth’s resources, while reducing the global populations of cars, trucks, livestock and, eventually, also humans. To avoid economic and ecological disasters, I recommend to decrease all automotive fuel use in Europe by up to 6 percent per year in 8 years, while switching to the increasingly rechargeable hybrid and all-electric cars, progressively driven by photovoltaic cells. The actual schedule of the rate of decrease should also depend on the exigencies of greenhouse gas abatement. The photovoltaic cell-battery-electric motor system is some 100 times more efficient than major agrofuel systems.

The paper is highly technical, which will turn off many people. But what I enjoy – and I believe is one of my strengths – is to distill technical information and present it so that it is more readily digestible for the layperson. My hope is that this essay succeeds in doing that.

The paper was presented at the 20th Round Table on Sustainable Development of Biofuels in Paris, and therefore contains a lot of Europe-specific discussion and recommendations. The paper covers a lot of ground. Petroleum depletion is discussed, and the business-as-usual scenario is discarded as simply not possible. Cellulosic ethanol is covered, with a close examination of the energy efficiency of Iogen‘s plant in Ottawa. This result is then compared to the energy efficiency claims of the six proposed demonstration plants in the U.S. The last section compares the potential of photovoltaic cells to biofuels for mitigating our depleting fossil fuel reserves.

Summarizing the Paper

Introduction

In the introduction, Professor Patzek states that world production of conventional petroleum peaked in 2006, and will decline exponentially within a decade. He suggests that heroic measures such as infill drilling, horizontal wells, and enhanced oil recovery methods can stem the decline initially, but this will lead to a steeper decline rate later on. He extrapolates the current per capita use of petroleum with the growth of population in the U.S., and concludes “that the US and the rest of the world soon will be on a head-on collision course.” He also states that the U.S. currently uses 33 times as much energy in transportation fuels than is required to feed the population.

Background

In this section, Professor Patzek outlines five constraints that impact humanity’s survival, followed by possible solutions given these constraints. The constraints include exponential population growth, overuse of the earth’s resources, and our current political structure in which “more is better.” He presents two solutions to our current situation: 1). Go extinct; or 2). Fundamentally and abruptly change. The status quo is not an option, as Patzek believes it will lead to solution (1). I understand that many doubt that (2) is possible, which is why they believe we are doomed. Personally, I believe the most likely solution is a combination of the two. People will go extinct as food and energy become unaffordable (this is happening even now), but there will be pockets of fundamental and abrupt change. Fast recognition and adaptation – both on a personal and governmental level – are going to be very important.

Patzek examines the impact of fossil fuel usage on population growth, and concludes that of the present world population, “4.5 billion people owe their existence to the Haber-Bosch ammonia process and the fossil fuel-driven, fundamentally unstable ‘green revolution,’ as well as to vaccines and antibiotics.”

He comments that too many in society consider themselves more knowledgeable about energy matters than they really are, and this is why we aren’t urgently confronting the problem. As his 2nd conclusion of the paper, he writes:

Business as usual will lead to a complete and practically immediate crash of the technically advanced societies and, perhaps, all humanity. This outcome will not be much different from a collapse of an overgrown colony of bacteria on a petri dish when its sugar food runs out and waste products build up.

He concludes this section by pointing out that we have been conditioned to think that technology is almost magic and will solve our problems. He quoted a biofuels expert who suggested “Biotechnology is not subject to the same laws of chemistry and physics as other technologies. In biology anything is possible, and the sky is the limit!”

Efficiency of Cellulosic Ethanol Refineries

This section was extremely interesting to me. Real energy efficiencies of cellulosic ethanol plants (which presently exist only on paper or in demonstration scale) are hard to come by. Those 4:1 or 8:1 energy returns that you often see claimed are hypothetical; nobody in the cellulosic ethanol business has demonstrated anything like this. Professor Patzek attempts to shed some light on this subject. In his words:

I start from a “reverse-engineering” calculation of energy efficiency of cellulosic ethanol production in an existing Iogen pilot plant, Ottawa, Canada. I then discuss the inflated energy efficiency claims of five out-of-six recipients of $385 millions of DOE grants to develop cellulosic ethanol refineries.

Using published information, Professor Patzek calculated the efficiency of the Iogen plant. He defined the efficiency (albeit by an equation that could have been more clear) as the BTUs of ethanol produced, divided by the theoretical maximum. His calculated efficiency of the process was 20%; input 1 BTU into the process and return 0.2 BTUs, for a net of -0.8 BTUs. This calculation is in the same form as Dr. Wang’s gasoline efficiency calculations – the initial BTUs of the feedstock are counted as an input into the process, and then the processing energy is counted against it. In simple terms, if you take 1 kilogram of wheat straw, add in the distillation energy and take credit for the heating value of the lignin, you have the denominator of the equation. The numerator is the heating value of the ethanol that was produced from that kilogram of wheat straw. If you started with 1 BTU of straw, and produced 1 BTU of ethanol, the efficiency is then governed purely by the distillation energy (essentially the amount of external energy required to drive the process).

Of particular note, the equation did take a credit for the lignin, which is always the assumption that cellulosic ethanol proponents use to obtain inflated energy returns. However, the most significant piece of the calculation for me – and one that Patzek did not call attention to – is that if you look at only the distillation energy (the 2nd term in the denominator of Eqn 1), it is 55% greater than the ethanol that is yielded from the distillation. That means that production of 1 BTU of cellulosic ethanol requires a distillation step that consumes 1.55 BTUs.

The reason for this is one I have stated numerous times. As Patzek writes “there is ca. 4% of alcohol in a batch of industrial wheat-straw beer, in contrast to 12 to 16% of ethanol in corn-ethanol refinery beers.”

I do note that if you take full credit for the heating value of the lignin, it just barely satisifies the distillation requirement. If you run through the math, the lignin BTU credit gives an energy balance of 1.05, which is worse than the 1.3 of corn ethanol plus by-product credits. But remember, the lignin in the process is not dry. It is very wet. Drying co-products in a corn ethanol plant requires a substantial input of energy. If lignin is to be used in a cellulosic ethanol plant, it will have to be dried.

Furthermore, even if the lignin is dry, no other energy inputs into the process have been considered (so this is not a complete energy balance calculation). In other words, if those inputs were all free (of course trucking the biomass back and forth will require significant energy inputs), and the lignin was dry, you would get 1.05 BTUs of cellulosic ethanol out for a lignin input of 1 BTU. Even presuming that Iogen has made major advances recently, it is not surprising why they have been slow to build a commercial facility; they know the score. Patzek concludes:

The Iogen plant in Ottawa, Canada, has operated well below name plate capacity for three years. Iogen should retain their trade secrets, but in exchange for the significant subsidies from the US and Canadian taxpayers they should tell us what the annual production of alcohols was, how much straw was used, and what the fossil fuel and electricity inputs were. The ethanol yield coefficient in kg of ethanol per kg straw dmb is key to public assessments of the new technology. Similar remarks pertain to the Novozymes projects heavily subsidized by the Danes. Until an existing pilot plant provides real, independently verified data on yield coefficients, mash ethanol concentrations, etc., all proposed cellulosic ethanol refinery designs are speculation.

Patzek then addresses the six proposed cellulosic ethanol plants that were awarded $385 million USD by the US Department of Energy. For reference, he gives the energy efficiency of Sasol’s coal-to-liquids (CTL) process as 42%, the efficiency of an average oil refinery as 88% (and I can verify that this number is spot on), and that of an optimized corn ethanol refinery as 37%.


Figure 1. Inflated Energy Efficiency Claims of Announced Cellulosic Ventures

Figure 1, from Patzek’s paper, compares the claimed efficiencies of the various cellulosic ventures. Of the six proposed plants, only Abengoa, reporting 25% estimated energy efficiency, was close to Patzek’s reverse-engineered efficiency for Iogen. The other five all claimed energy efficiencies in the 40-60% range. The most optimistic was Vinod Khosla‘s former Kergy (now Range Fuels) venture. See the last section of Cellulosic Ethanol vs. Biomass Gasification for some discussion on Kergy. This process is actually a gasification process, and as such won’t have the same sorts of issues that Patzek documented for Iogen. But I don’t think in an apples-to-apples comparison they can beat a CTL process on efficiency, because it is much easier to handle coal than biomass (not that I endorse CTL). They are also going to have one problem that the others don’t, and that is the production of significant amounts of various mixed alcohols.

There are theoretical reasons why cellulose is unlikely to produce an ethanol concentration in the range of corn ethanol. Patzek writes that at “about 0.2 to 0.25 kg of straw/L, the mash is barely pumpable“, and states that this straw concentration will result in a fermentation beer of 4.4% ethanol at a maximum. Yet five of the proposed plants are claiming energy efficiencies that are as great or greater than those of corn ethanol plants.

Where Will the Agrofuel Biomass Come From?

In this section, Patzek tackles an issue that I have also addressed: Where could we get that much biomass to begin with? Patzek asks and answers: “Where, how much, and for how long will the Earth produce the extra biomass to quench our unending thirst to drive 1 billion cars and trucks? The answer to this question is immediate and unequivocal: Nowhere, close to nothing, and for a very short time indeed.”

In the interest of brevity, I won’t go into the details of this section. It is a discussion of Net Primary Productivity and Net Ecosystem Productivity, as well as the USDA/DOE billion ton vision – Biomass as feedstock for a bioenergy and bioproducts industry: The technical feasibility of a billion-ton annual supply (PDF download). The short of it is that Patzek argues that the biomass is simply not available, and attempting to grow and process enough biomass to continue the business-as-usual model “would be a continental-scale ecologic and economic disaster of biblical proportions.”

Photovoltaic Cells vs. Agrofuels

The analysis of Iogen’s energy balance and this final section were for me the gems of this paper. In this section, Patzek looks at a square meter of land, and compares the energy potential of various biofuels, solar power, and wind power. He also shows the amount of energy if this square meter was an oil field producing oil for 30 years, but that limits the discussion to a very small fraction of the earth’s surface. Also, as Patzek wrote, “this resource is finite and irreplaceable and after 30 years there is no producible oil left in it.” So, I am not going to focus on the oil comparison in this section.

For his comparisons, Patzek looked at photovoltaic cells, wind turbines, corn ethanol, sugarcane ethanol, corn stover ethanol, and Acacia and Eucalyptus for FT-diesel, ethanol, or electricity. He uses the actual demonstrated solar capture efficiency of these processes. Figure 2 shows how the various sources stacked up:


Figure 2. Professor Patzek’s Comparison of Various Renewable Options

As shown in the figure, based on Professor Patzek’s methodology solar PV is the only option considered that has a legitimate chance to offset a fair portion of our current oil production. Wind came in a distant second. Of the biomass applications, Acacia for electricity ranked the highest. It is significant to note that the top three options all involved production of electricity.

Interestingly, while the solar capture of sugarcane ethanol ranked lower than those three options, Patzek comes to the same conclusion that I did in my essay Brazilian Ethanol is Sustainable. He writes:

Because of the unique ability of satisfying the huge CExC [RR: Defined as cumulative exergy consumption] in cane crushing, fermentation, and ethanol distillation (0.41 W/m2), as well as fresh bagasse + “trash” drying (0.27 W/m2), with the chemical exergy of bagasse and the attached “trash,” sugarcane is the only industrial energy plant that may be called “sustainable.”

Patzek also performs a calculation designed to show how much area is needed to drive a hypothetical car 15,000 miles per year on some of the energy options. He concludes that “for each 1 m2 of medium-quality oil fields one needs 620 m2 of corn fields to replace gasoline with corn ethanol and pay for the free energy costs of the ethanol production. Similarly, one can drive our example cars for one year from ~30 m2 of oil fields, 90 m2 of photovoltaic cells, 1100 m2 of wind turbines, and ~18000 m2 of corn fields.”

However, one key item not addressed in this essay – and for me the key to making this vision work – is improving energy storage technology. Patzek presumes continued improvement of battery technology. In fact, he writes “With time the batteries will get better, and electric motors will take over powering the vehicles.” Is that a reasonable assumption? I don’t know. I would have liked to have seen this explored in a bit more detail. One hopes that this isn’t a situation in which Patzek is presuming “those guys will figure it out.”

Professor Patzek’s Conclusions

I will let Professor Patzek’s conclusions speak for themselves. Here are some excerpts:

In this paper I have painted a radical vision of a world in which fossil fuels and agrofuels will be used increasingly less in transportation vehicles. Gradually, these fuels will be replaced by electricity stored in the vehicle batteries. With time the batteries will get better, and electric motors will take over powering the vehicles. The sources of electricity for the batteries will be increasingly solar photovoltaic cells and wind turbines. The vagaries of cloudy skies and irregular winds will be alleviated to a large degree by the surplus batteries being recharged and shared locally, with no transmission lines out of a neighborhood or city.

I have shown that even mediocre solar cells that cost 1/3 of their life-time electricity production to be manufactured are at least 100 times more efficient than the current major agrofuel systems. When deployed these cells will not burn forests; kill living things on land, in the air, and in the oceans; erode soil; contaminate water; and emit astronomic quantities of greenhouse gases.

Finally, no future transportation system will allow complete “freedom of personal transportation” for everyone. I suggest that good public transportation systems will free many, if not most people from personal transportation.

My Conclusions

I am not sure whether Professor Patzek believes that biofuels have no place at all among our future energy options. In my opinion, there is a place for them, albeit in niche applications and not as a major energy source. I think we will continue to have a need for some long-range transportation options (e.g., shipping, airline transportation) that would be difficult to electrify. But for the most part, the future has to be electric. The sooner we shift focus from biofuels to electric transportation, the better.

October 1, 2007 Posted by | cellulosic ethanol, electric cars, phev, solar power, sustainability | 33 Comments

Review: How Can We Outlive Our Way of Life?

“Have the guts to consider the silent consequences when standing in front of the next snake-oil humanitarian.” Nassim Nicholas Taleb in The Black Swan

I believe our generation faces a sobering choice: Take serious steps to reduce our fossil fuel usage now – and this will undoubtedly entail some amount of hardship – or leave it to our children to face a great deal of hardship. I firmly believe this is our choice, and we must look to solutions that move us in that direction. I also believe that if most people understood that we are pushing a very serious problem onto our children – instead of assuming scientists and engineers will solve the problem – then we would collectively pursue a solution with far greater urgency.

Berkeley Professor Tad Patzek, who has written many articles that are critical of our present attempts to replace fossil fuels with biofuels, has just published a new article in which he also discusses solutions:

How Can We Outlive Our Way of Life? (PDF download)

Many of you know Tad Patzek as the co-author of a number of papers with David Pimentel. If you are pro corn-ethanol, then you have probably been conditioned to discount everything Professor Patzek writes. But even if you disagree with his corn ethanol position, there is still a lot to take away from this paper. Patzek’s conclusion on cellulosic ethanol is the same as my own: The status of cellulosic ethanol has been exaggerated and over-hyped, and the solution that we really ought to be pursuing is electric. The abstract of the paper reads:

In this paper I outline the rational, science-based arguments that question current wisdom of replacing fossil plant fuels (coal, oil and natural gas) with fresh plant agrofuels. This 1:1 replacement is absolutely impossible for more than a few years, because of the ways the planet Earth works and maintains life. After these few years, the denuded Earth will be a different planet, hostile to human life. I argue that with the current set of objective constraints a continuous stable solution to human life cannot exist in the near-future, unless we all rapidly implement much more limited ways of using the Earth’s resources, while reducing the global populations of cars, trucks, livestock and, eventually, also humans. To avoid economic and ecological disasters, I recommend to decrease all automotive fuel use in Europe by up to 6 percent per year in 8 years, while switching to the increasingly rechargeable hybrid and all-electric cars, progressively driven by photovoltaic cells. The actual schedule of the rate of decrease should also depend on the exigencies of greenhouse gas abatement. The photovoltaic cell-battery-electric motor system is some 100 times more efficient than major agrofuel systems.

The paper is highly technical, which will turn off many people. But what I enjoy – and I believe is one of my strengths – is to distill technical information and present it so that it is more readily digestible for the layperson. My hope is that this essay succeeds in doing that.

The paper was presented at the 20th Round Table on Sustainable Development of Biofuels in Paris, and therefore contains a lot of Europe-specific discussion and recommendations. The paper covers a lot of ground. Petroleum depletion is discussed, and the business-as-usual scenario is discarded as simply not possible. Cellulosic ethanol is covered, with a close examination of the energy efficiency of Iogen‘s plant in Ottawa. This result is then compared to the energy efficiency claims of the six proposed demonstration plants in the U.S. The last section compares the potential of photovoltaic cells to biofuels for mitigating our depleting fossil fuel reserves.

Summarizing the Paper

Introduction

In the introduction, Professor Patzek states that world production of conventional petroleum peaked in 2006, and will decline exponentially within a decade. He suggests that heroic measures such as infill drilling, horizontal wells, and enhanced oil recovery methods can stem the decline initially, but this will lead to a steeper decline rate later on. He extrapolates the current per capita use of petroleum with the growth of population in the U.S., and concludes “that the US and the rest of the world soon will be on a head-on collision course.” He also states that the U.S. currently uses 33 times as much energy in transportation fuels than is required to feed the population.

Background

In this section, Professor Patzek outlines five constraints that impact humanity’s survival, followed by possible solutions given these constraints. The constraints include exponential population growth, overuse of the earth’s resources, and our current political structure in which “more is better.” He presents two solutions to our current situation: 1). Go extinct; or 2). Fundamentally and abruptly change. The status quo is not an option, as Patzek believes it will lead to solution (1). I understand that many doubt that (2) is possible, which is why they believe we are doomed. Personally, I believe the most likely solution is a combination of the two. People will go extinct as food and energy become unaffordable (this is happening even now), but there will be pockets of fundamental and abrupt change. Fast recognition and adaptation – both on a personal and governmental level – are going to be very important.

Patzek examines the impact of fossil fuel usage on population growth, and concludes that of the present world population, “4.5 billion people owe their existence to the Haber-Bosch ammonia process and the fossil fuel-driven, fundamentally unstable ‘green revolution,’ as well as to vaccines and antibiotics.”

He comments that too many in society consider themselves more knowledgeable about energy matters than they really are, and this is why we aren’t urgently confronting the problem. As his 2nd conclusion of the paper, he writes:

Business as usual will lead to a complete and practically immediate crash of the technically advanced societies and, perhaps, all humanity. This outcome will not be much different from a collapse of an overgrown colony of bacteria on a petri dish when its sugar food runs out and waste products build up.

He concludes this section by pointing out that we have been conditioned to think that technology is almost magic and will solve our problems. He quoted a biofuels expert who suggested “Biotechnology is not subject to the same laws of chemistry and physics as other technologies. In biology anything is possible, and the sky is the limit!”

Efficiency of Cellulosic Ethanol Refineries

This section was extremely interesting to me. Real energy efficiencies of cellulosic ethanol plants (which presently exist only on paper or in demonstration scale) are hard to come by. Those 4:1 or 8:1 energy returns that you often see claimed are hypothetical; nobody in the cellulosic ethanol business has demonstrated anything like this. Professor Patzek attempts to shed some light on this subject. In his words:

I start from a “reverse-engineering” calculation of energy efficiency of cellulosic ethanol production in an existing Iogen pilot plant, Ottawa, Canada. I then discuss the inflated energy efficiency claims of five out-of-six recipients of $385 millions of DOE grants to develop cellulosic ethanol refineries.

Using published information, Professor Patzek calculated the efficiency of the Iogen plant. He defined the efficiency (albeit by an equation that could have been more clear) as the BTUs of ethanol produced, divided by the theoretical maximum. His calculated efficiency of the process was 20%; input 1 BTU into the process and return 0.2 BTUs, for a net of -0.8 BTUs. This calculation is in the same form as Dr. Wang’s gasoline efficiency calculations – the initial BTUs of the feedstock are counted as an input into the process, and then the processing energy is counted against it. In simple terms, if you take 1 kilogram of wheat straw, add in the distillation energy and take credit for the heating value of the lignin, you have the denominator of the equation. The numerator is the heating value of the ethanol that was produced from that kilogram of wheat straw. If you started with 1 BTU of straw, and produced 1 BTU of ethanol, the efficiency is then governed purely by the distillation energy (essentially the amount of external energy required to drive the process).

Of particular note, the equation did take a credit for the lignin, which is always the assumption that cellulosic ethanol proponents use to obtain inflated energy returns. However, the most significant piece of the calculation for me – and one that Patzek did not call attention to – is that if you look at only the distillation energy (the 2nd term in the denominator of Eqn 1), it is 55% greater than the ethanol that is yielded from the distillation. That means that production of 1 BTU of cellulosic ethanol requires a distillation step that consumes 1.55 BTUs.

The reason for this is one I have stated numerous times. As Patzek writes “there is ca. 4% of alcohol in a batch of industrial wheat-straw beer, in contrast to 12 to 16% of ethanol in corn-ethanol refinery beers.”

I do note that if you take full credit for the heating value of the lignin, it just barely satisifies the distillation requirement. If you run through the math, the lignin BTU credit gives an energy balance of 1.05, which is worse than the 1.3 of corn ethanol plus by-product credits. But remember, the lignin in the process is not dry. It is very wet. Drying co-products in a corn ethanol plant requires a substantial input of energy. If lignin is to be used in a cellulosic ethanol plant, it will have to be dried.

Furthermore, even if the lignin is dry, no other energy inputs into the process have been considered (so this is not a complete energy balance calculation). In other words, if those inputs were all free (of course trucking the biomass back and forth will require significant energy inputs), and the lignin was dry, you would get 1.05 BTUs of cellulosic ethanol out for a lignin input of 1 BTU. Even presuming that Iogen has made major advances recently, it is not surprising why they have been slow to build a commercial facility; they know the score. Patzek concludes:

The Iogen plant in Ottawa, Canada, has operated well below name plate capacity for three years. Iogen should retain their trade secrets, but in exchange for the significant subsidies from the US and Canadian taxpayers they should tell us what the annual production of alcohols was, how much straw was used, and what the fossil fuel and electricity inputs were. The ethanol yield coefficient in kg of ethanol per kg straw dmb is key to public assessments of the new technology. Similar remarks pertain to the Novozymes projects heavily subsidized by the Danes. Until an existing pilot plant provides real, independently verified data on yield coefficients, mash ethanol concentrations, etc., all proposed cellulosic ethanol refinery designs are speculation.

Patzek then addresses the six proposed cellulosic ethanol plants that were awarded $385 million USD by the US Department of Energy. For reference, he gives the energy efficiency of Sasol’s coal-to-liquids (CTL) process as 42%, the efficiency of an average oil refinery as 88% (and I can verify that this number is spot on), and that of an optimized corn ethanol refinery as 37%.


Figure 1. Inflated Energy Efficiency Claims of Announced Cellulosic Ventures

Figure 1, from Patzek’s paper, compares the claimed efficiencies of the various cellulosic ventures. Of the six proposed plants, only Abengoa, reporting 25% estimated energy efficiency, was close to Patzek’s reverse-engineered efficiency for Iogen. The other five all claimed energy efficiencies in the 40-60% range. The most optimistic was Vinod Khosla‘s former Kergy (now Range Fuels) venture. See the last section of Cellulosic Ethanol vs. Biomass Gasification for some discussion on Kergy. This process is actually a gasification process, and as such won’t have the same sorts of issues that Patzek documented for Iogen. But I don’t think in an apples-to-apples comparison they can beat a CTL process on efficiency, because it is much easier to handle coal than biomass (not that I endorse CTL). They are also going to have one problem that the others don’t, and that is the production of significant amounts of various mixed alcohols.

There are theoretical reasons why cellulose is unlikely to produce an ethanol concentration in the range of corn ethanol. Patzek writes that at “about 0.2 to 0.25 kg of straw/L, the mash is barely pumpable“, and states that this straw concentration will result in a fermentation beer of 4.4% ethanol at a maximum. Yet five of the proposed plants are claiming energy efficiencies that are as great or greater than those of corn ethanol plants.

Where Will the Agrofuel Biomass Come From?

In this section, Patzek tackles an issue that I have also addressed: Where could we get that much biomass to begin with? Patzek asks and answers: “Where, how much, and for how long will the Earth produce the extra biomass to quench our unending thirst to drive 1 billion cars and trucks? The answer to this question is immediate and unequivocal: Nowhere, close to nothing, and for a very short time indeed.”

In the interest of brevity, I won’t go into the details of this section. It is a discussion of Net Primary Productivity and Net Ecosystem Productivity, as well as the USDA/DOE billion ton vision – Biomass as feedstock for a bioenergy and bioproducts industry: The technical feasibility of a billion-ton annual supply (PDF download). The short of it is that Patzek argues that the biomass is simply not available, and attempting to grow and process enough biomass to continue the business-as-usual model “would be a continental-scale ecologic and economic disaster of biblical proportions.”

Photovoltaic Cells vs. Agrofuels

The analysis of Iogen’s energy balance and this final section were for me the gems of this paper. In this section, Patzek looks at a square meter of land, and compares the energy potential of various biofuels, solar power, and wind power. He also shows the amount of energy if this square meter was an oil field producing oil for 30 years, but that limits the discussion to a very small fraction of the earth’s surface. Also, as Patzek wrote, “this resource is finite and irreplaceable and after 30 years there is no producible oil left in it.” So, I am not going to focus on the oil comparison in this section.

For his comparisons, Patzek looked at photovoltaic cells, wind turbines, corn ethanol, sugarcane ethanol, corn stover ethanol, and Acacia and Eucalyptus for FT-diesel, ethanol, or electricity. He uses the actual demonstrated solar capture efficiency of these processes. Figure 2 shows how the various sources stacked up:


Figure 2. Professor Patzek’s Comparison of Various Renewable Options

As shown in the figure, based on Professor Patzek’s methodology solar PV is the only option considered that has a legitimate chance to offset a fair portion of our current oil production. Wind came in a distant second. Of the biomass applications, Acacia for electricity ranked the highest. It is significant to note that the top three options all involved production of electricity.

Interestingly, while the solar capture of sugarcane ethanol ranked lower than those three options, Patzek comes to the same conclusion that I did in my essay Brazilian Ethanol is Sustainable. He writes:

Because of the unique ability of satisfying the huge CExC [RR: Defined as cumulative exergy consumption] in cane crushing, fermentation, and ethanol distillation (0.41 W/m2), as well as fresh bagasse + “trash” drying (0.27 W/m2), with the chemical exergy of bagasse and the attached “trash,” sugarcane is the only industrial energy plant that may be called “sustainable.”

Patzek also performs a calculation designed to show how much area is needed to drive a hypothetical car 15,000 miles per year on some of the energy options. He concludes that “for each 1 m2 of medium-quality oil fields one needs 620 m2 of corn fields to replace gasoline with corn ethanol and pay for the free energy costs of the ethanol production. Similarly, one can drive our example cars for one year from ~30 m2 of oil fields, 90 m2 of photovoltaic cells, 1100 m2 of wind turbines, and ~18000 m2 of corn fields.”

However, one key item not addressed in this essay – and for me the key to making this vision work – is improving energy storage technology. Patzek presumes continued improvement of battery technology. In fact, he writes “With time the batteries will get better, and electric motors will take over powering the vehicles.” Is that a reasonable assumption? I don’t know. I would have liked to have seen this explored in a bit more detail. One hopes that this isn’t a situation in which Patzek is presuming “those guys will figure it out.”

Professor Patzek’s Conclusions

I will let Professor Patzek’s conclusions speak for themselves. Here are some excerpts:

In this paper I have painted a radical vision of a world in which fossil fuels and agrofuels will be used increasingly less in transportation vehicles. Gradually, these fuels will be replaced by electricity stored in the vehicle batteries. With time the batteries will get better, and electric motors will take over powering the vehicles. The sources of electricity for the batteries will be increasingly solar photovoltaic cells and wind turbines. The vagaries of cloudy skies and irregular winds will be alleviated to a large degree by the surplus batteries being recharged and shared locally, with no transmission lines out of a neighborhood or city.

I have shown that even mediocre solar cells that cost 1/3 of their life-time electricity production to be manufactured are at least 100 times more efficient than the current major agrofuel systems. When deployed these cells will not burn forests; kill living things on land, in the air, and in the oceans; erode soil; contaminate water; and emit astronomic quantities of greenhouse gases.

Finally, no future transportation system will allow complete “freedom of personal transportation” for everyone. I suggest that good public transportation systems will free many, if not most people from personal transportation.

My Conclusions

I am not sure whether Professor Patzek believes that biofuels have no place at all among our future energy options. In my opinion, there is a place for them, albeit in niche applications and not as a major energy source. I think we will continue to have a need for some long-range transportation options (e.g., shipping, airline transportation) that would be difficult to electrify. But for the most part, the future has to be electric. The sooner we shift focus from biofuels to electric transportation, the better.

October 1, 2007 Posted by | cellulosic ethanol, electric cars, phev, solar power, sustainability | 33 Comments

Review: How Can We Outlive Our Way of Life?

“Have the guts to consider the silent consequences when standing in front of the next snake-oil humanitarian.” Nassim Nicholas Taleb in The Black Swan

I believe our generation faces a sobering choice: Take serious steps to reduce our fossil fuel usage now – and this will undoubtedly entail some amount of hardship – or leave it to our children to face a great deal of hardship. I firmly believe this is our choice, and we must look to solutions that move us in that direction. I also believe that if most people understood that we are pushing a very serious problem onto our children – instead of assuming scientists and engineers will solve the problem – then we would collectively pursue a solution with far greater urgency.

Berkeley Professor Tad Patzek, who has written many articles that are critical of our present attempts to replace fossil fuels with biofuels, has just published a new article in which he also discusses solutions:

How Can We Outlive Our Way of Life? (PDF download)

Many of you know Tad Patzek as the co-author of a number of papers with David Pimentel. If you are pro corn-ethanol, then you have probably been conditioned to discount everything Professor Patzek writes. But even if you disagree with his corn ethanol position, there is still a lot to take away from this paper. Patzek’s conclusion on cellulosic ethanol is the same as my own: The status of cellulosic ethanol has been exaggerated and over-hyped, and the solution that we really ought to be pursuing is electric. The abstract of the paper reads:

In this paper I outline the rational, science-based arguments that question current wisdom of replacing fossil plant fuels (coal, oil and natural gas) with fresh plant agrofuels. This 1:1 replacement is absolutely impossible for more than a few years, because of the ways the planet Earth works and maintains life. After these few years, the denuded Earth will be a different planet, hostile to human life. I argue that with the current set of objective constraints a continuous stable solution to human life cannot exist in the near-future, unless we all rapidly implement much more limited ways of using the Earth’s resources, while reducing the global populations of cars, trucks, livestock and, eventually, also humans. To avoid economic and ecological disasters, I recommend to decrease all automotive fuel use in Europe by up to 6 percent per year in 8 years, while switching to the increasingly rechargeable hybrid and all-electric cars, progressively driven by photovoltaic cells. The actual schedule of the rate of decrease should also depend on the exigencies of greenhouse gas abatement. The photovoltaic cell-battery-electric motor system is some 100 times more efficient than major agrofuel systems.

The paper is highly technical, which will turn off many people. But what I enjoy – and I believe is one of my strengths – is to distill technical information and present it so that it is more readily digestible for the layperson. My hope is that this essay succeeds in doing that.

The paper was presented at the 20th Round Table on Sustainable Development of Biofuels in Paris, and therefore contains a lot of Europe-specific discussion and recommendations. The paper covers a lot of ground. Petroleum depletion is discussed, and the business-as-usual scenario is discarded as simply not possible. Cellulosic ethanol is covered, with a close examination of the energy efficiency of Iogen‘s plant in Ottawa. This result is then compared to the energy efficiency claims of the six proposed demonstration plants in the U.S. The last section compares the potential of photovoltaic cells to biofuels for mitigating our depleting fossil fuel reserves.

Summarizing the Paper

Introduction

In the introduction, Professor Patzek states that world production of conventional petroleum peaked in 2006, and will decline exponentially within a decade. He suggests that heroic measures such as infill drilling, horizontal wells, and enhanced oil recovery methods can stem the decline initially, but this will lead to a steeper decline rate later on. He extrapolates the current per capita use of petroleum with the growth of population in the U.S., and concludes “that the US and the rest of the world soon will be on a head-on collision course.” He also states that the U.S. currently uses 33 times as much energy in transportation fuels than is required to feed the population.

Background

In this section, Professor Patzek outlines five constraints that impact humanity’s survival, followed by possible solutions given these constraints. The constraints include exponential population growth, overuse of the earth’s resources, and our current political structure in which “more is better.” He presents two solutions to our current situation: 1). Go extinct; or 2). Fundamentally and abruptly change. The status quo is not an option, as Patzek believes it will lead to solution (1). I understand that many doubt that (2) is possible, which is why they believe we are doomed. Personally, I believe the most likely solution is a combination of the two. People will go extinct as food and energy become unaffordable (this is happening even now), but there will be pockets of fundamental and abrupt change. Fast recognition and adaptation – both on a personal and governmental level – are going to be very important.

Patzek examines the impact of fossil fuel usage on population growth, and concludes that of the present world population, “4.5 billion people owe their existence to the Haber-Bosch ammonia process and the fossil fuel-driven, fundamentally unstable ‘green revolution,’ as well as to vaccines and antibiotics.”

He comments that too many in society consider themselves more knowledgeable about energy matters than they really are, and this is why we aren’t urgently confronting the problem. As his 2nd conclusion of the paper, he writes:

Business as usual will lead to a complete and practically immediate crash of the technically advanced societies and, perhaps, all humanity. This outcome will not be much different from a collapse of an overgrown colony of bacteria on a petri dish when its sugar food runs out and waste products build up.

He concludes this section by pointing out that we have been conditioned to think that technology is almost magic and will solve our problems. He quoted a biofuels expert who suggested “Biotechnology is not subject to the same laws of chemistry and physics as other technologies. In biology anything is possible, and the sky is the limit!”

Efficiency of Cellulosic Ethanol Refineries

This section was extremely interesting to me. Real energy efficiencies of cellulosic ethanol plants (which presently exist only on paper or in demonstration scale) are hard to come by. Those 4:1 or 8:1 energy returns that you often see claimed are hypothetical; nobody in the cellulosic ethanol business has demonstrated anything like this. Professor Patzek attempts to shed some light on this subject. In his words:

I start from a “reverse-engineering” calculation of energy efficiency of cellulosic ethanol production in an existing Iogen pilot plant, Ottawa, Canada. I then discuss the inflated energy efficiency claims of five out-of-six recipients of $385 millions of DOE grants to develop cellulosic ethanol refineries.

Using published information, Professor Patzek calculated the efficiency of the Iogen plant. He defined the efficiency (albeit by an equation that could have been more clear) as the BTUs of ethanol produced, divided by the theoretical maximum. His calculated efficiency of the process was 20%; input 1 BTU into the process and return 0.2 BTUs, for a net of -0.8 BTUs. This calculation is in the same form as Dr. Wang’s gasoline efficiency calculations – the initial BTUs of the feedstock are counted as an input into the process, and then the processing energy is counted against it. In simple terms, if you take 1 kilogram of wheat straw, add in the distillation energy and take credit for the heating value of the lignin, you have the denominator of the equation. The numerator is the heating value of the ethanol that was produced from that kilogram of wheat straw. If you started with 1 BTU of straw, and produced 1 BTU of ethanol, the efficiency is then governed purely by the distillation energy (essentially the amount of external energy required to drive the process).

Of particular note, the equation did take a credit for the lignin, which is always the assumption that cellulosic ethanol proponents use to obtain inflated energy returns. However, the most significant piece of the calculation for me – and one that Patzek did not call attention to – is that if you look at only the distillation energy (the 2nd term in the denominator of Eqn 1), it is 55% greater than the ethanol that is yielded from the distillation. That means that production of 1 BTU of cellulosic ethanol requires a distillation step that consumes 1.55 BTUs.

The reason for this is one I have stated numerous times. As Patzek writes “there is ca. 4% of alcohol in a batch of industrial wheat-straw beer, in contrast to 12 to 16% of ethanol in corn-ethanol refinery beers.”

I do note that if you take full credit for the heating value of the lignin, it just barely satisifies the distillation requirement. If you run through the math, the lignin BTU credit gives an energy balance of 1.05, which is worse than the 1.3 of corn ethanol plus by-product credits. But remember, the lignin in the process is not dry. It is very wet. Drying co-products in a corn ethanol plant requires a substantial input of energy. If lignin is to be used in a cellulosic ethanol plant, it will have to be dried.

Furthermore, even if the lignin is dry, no other energy inputs into the process have been considered (so this is not a complete energy balance calculation). In other words, if those inputs were all free (of course trucking the biomass back and forth will require significant energy inputs), and the lignin was dry, you would get 1.05 BTUs of cellulosic ethanol out for a lignin input of 1 BTU. Even presuming that Iogen has made major advances recently, it is not surprising why they have been slow to build a commercial facility; they know the score. Patzek concludes:

The Iogen plant in Ottawa, Canada, has operated well below name plate capacity for three years. Iogen should retain their trade secrets, but in exchange for the significant subsidies from the US and Canadian taxpayers they should tell us what the annual production of alcohols was, how much straw was used, and what the fossil fuel and electricity inputs were. The ethanol yield coefficient in kg of ethanol per kg straw dmb is key to public assessments of the new technology. Similar remarks pertain to the Novozymes projects heavily subsidized by the Danes. Until an existing pilot plant provides real, independently verified data on yield coefficients, mash ethanol concentrations, etc., all proposed cellulosic ethanol refinery designs are speculation.

Patzek then addresses the six proposed cellulosic ethanol plants that were awarded $385 million USD by the US Department of Energy. For reference, he gives the energy efficiency of Sasol’s coal-to-liquids (CTL) process as 42%, the efficiency of an average oil refinery as 88% (and I can verify that this number is spot on), and that of an optimized corn ethanol refinery as 37%.


Figure 1. Inflated Energy Efficiency Claims of Announced Cellulosic Ventures

Figure 1, from Patzek’s paper, compares the claimed efficiencies of the various cellulosic ventures. Of the six proposed plants, only Abengoa, reporting 25% estimated energy efficiency, was close to Patzek’s reverse-engineered efficiency for Iogen. The other five all claimed energy efficiencies in the 40-60% range. The most optimistic was Vinod Khosla‘s former Kergy (now Range Fuels) venture. See the last section of Cellulosic Ethanol vs. Biomass Gasification for some discussion on Kergy. This process is actually a gasification process, and as such won’t have the same sorts of issues that Patzek documented for Iogen. But I don’t think in an apples-to-apples comparison they can beat a CTL process on efficiency, because it is much easier to handle coal than biomass (not that I endorse CTL). They are also going to have one problem that the others don’t, and that is the production of significant amounts of various mixed alcohols.

There are theoretical reasons why cellulose is unlikely to produce an ethanol concentration in the range of corn ethanol. Patzek writes that at “about 0.2 to 0.25 kg of straw/L, the mash is barely pumpable“, and states that this straw concentration will result in a fermentation beer of 4.4% ethanol at a maximum. Yet five of the proposed plants are claiming energy efficiencies that are as great or greater than those of corn ethanol plants.

Where Will the Agrofuel Biomass Come From?

In this section, Patzek tackles an issue that I have also addressed: Where could we get that much biomass to begin with? Patzek asks and answers: “Where, how much, and for how long will the Earth produce the extra biomass to quench our unending thirst to drive 1 billion cars and trucks? The answer to this question is immediate and unequivocal: Nowhere, close to nothing, and for a very short time indeed.”

In the interest of brevity, I won’t go into the details of this section. It is a discussion of Net Primary Productivity and Net Ecosystem Productivity, as well as the USDA/DOE billion ton vision – Biomass as feedstock for a bioenergy and bioproducts industry: The technical feasibility of a billion-ton annual supply (PDF download). The short of it is that Patzek argues that the biomass is simply not available, and attempting to grow and process enough biomass to continue the business-as-usual model “would be a continental-scale ecologic and economic disaster of biblical proportions.”

Photovoltaic Cells vs. Agrofuels

The analysis of Iogen’s energy balance and this final section were for me the gems of this paper. In this section, Patzek looks at a square meter of land, and compares the energy potential of various biofuels, solar power, and wind power. He also shows the amount of energy if this square meter was an oil field producing oil for 30 years, but that limits the discussion to a very small fraction of the earth’s surface. Also, as Patzek wrote, “this resource is finite and irreplaceable and after 30 years there is no producible oil left in it.” So, I am not going to focus on the oil comparison in this section.

For his comparisons, Patzek looked at photovoltaic cells, wind turbines, corn ethanol, sugarcane ethanol, corn stover ethanol, and Acacia and Eucalyptus for FT-diesel, ethanol, or electricity. He uses the actual demonstrated solar capture efficiency of these processes. Figure 2 shows how the various sources stacked up:


Figure 2. Professor Patzek’s Comparison of Various Renewable Options

As shown in the figure, based on Professor Patzek’s methodology solar PV is the only option considered that has a legitimate chance to offset a fair portion of our current oil production. Wind came in a distant second. Of the biomass applications, Acacia for electricity ranked the highest. It is significant to note that the top three options all involved production of electricity.

Interestingly, while the solar capture of sugarcane ethanol ranked lower than those three options, Patzek comes to the same conclusion that I did in my essay Brazilian Ethanol is Sustainable. He writes:

Because of the unique ability of satisfying the huge CExC [RR: Defined as cumulative exergy consumption] in cane crushing, fermentation, and ethanol distillation (0.41 W/m2), as well as fresh bagasse + “trash” drying (0.27 W/m2), with the chemical exergy of bagasse and the attached “trash,” sugarcane is the only industrial energy plant that may be called “sustainable.”

Patzek also performs a calculation designed to show how much area is needed to drive a hypothetical car 15,000 miles per year on some of the energy options. He concludes that “for each 1 m2 of medium-quality oil fields one needs 620 m2 of corn fields to replace gasoline with corn ethanol and pay for the free energy costs of the ethanol production. Similarly, one can drive our example cars for one year from ~30 m2 of oil fields, 90 m2 of photovoltaic cells, 1100 m2 of wind turbines, and ~18000 m2 of corn fields.”

However, one key item not addressed in this essay – and for me the key to making this vision work – is improving energy storage technology. Patzek presumes continued improvement of battery technology. In fact, he writes “With time the batteries will get better, and electric motors will take over powering the vehicles.” Is that a reasonable assumption? I don’t know. I would have liked to have seen this explored in a bit more detail. One hopes that this isn’t a situation in which Patzek is presuming “those guys will figure it out.”

Professor Patzek’s Conclusions

I will let Professor Patzek’s conclusions speak for themselves. Here are some excerpts:

In this paper I have painted a radical vision of a world in which fossil fuels and agrofuels will be used increasingly less in transportation vehicles. Gradually, these fuels will be replaced by electricity stored in the vehicle batteries. With time the batteries will get better, and electric motors will take over powering the vehicles. The sources of electricity for the batteries will be increasingly solar photovoltaic cells and wind turbines. The vagaries of cloudy skies and irregular winds will be alleviated to a large degree by the surplus batteries being recharged and shared locally, with no transmission lines out of a neighborhood or city.

I have shown that even mediocre solar cells that cost 1/3 of their life-time electricity production to be manufactured are at least 100 times more efficient than the current major agrofuel systems. When deployed these cells will not burn forests; kill living things on land, in the air, and in the oceans; erode soil; contaminate water; and emit astronomic quantities of greenhouse gases.

Finally, no future transportation system will allow complete “freedom of personal transportation” for everyone. I suggest that good public transportation systems will free many, if not most people from personal transportation.

My Conclusions

I am not sure whether Professor Patzek believes that biofuels have no place at all among our future energy options. In my opinion, there is a place for them, albeit in niche applications and not as a major energy source. I think we will continue to have a need for some long-range transportation options (e.g., shipping, airline transportation) that would be difficult to electrify. But for the most part, the future has to be electric. The sooner we shift focus from biofuels to electric transportation, the better.

October 1, 2007 Posted by | cellulosic ethanol, electric cars, phev, solar power, sustainability | Comments Off on Review: How Can We Outlive Our Way of Life?