How Corn Ethanol Destroys Rain Forests

At least according to a new story in Time, which is a blistering critique of our ethanol policies. It also documents the change of heart that has taken place among some prominent ethanol boosters.

The Clean Energy Scam

In Brazil, for instance, only a tiny portion of the Amazon is being torn down to grow the sugarcane that fuels most Brazilian cars. More deforestation results from a chain reaction so vast it’s subtle: U.S. farmers are selling one-fifth of their corn to ethanol production, so U.S. soybean farmers are switching to corn, so Brazilian soybean farmers are expanding into cattle pastures, so Brazilian cattlemen are displaced to the Amazon. It’s the remorseless economics of commodities markets.

It is a sobering article, and well worth a read. It does contain some errors. First, the author repeats (and actually embellishes) the claim that ethanol “provide(s) 45% of Brazil’s fuel.” As I have shown previously, from actual energy usage statistics, it is about 17% of transportation fuel on a volumetric basis, and 10% on an energy equivalent basis. Second, on carbon emissions, the author mentions that the “gains approached 90% for more efficient fuels.” Important to note that while these 80 or 90% carbon emission reductions for next generation ethanol are liberally thrown around, they are all based on models. Nobody has actually demonstrated this. To demonstrate it requires a cellulosic ethanol plant that is highly integrated. The waste biomass must be used to provide power for the plant. There are a number of problems to be worked through – if not we would already have a cellulosic ethanol industry – but these numbers continue to be repeated as if they were demonstrated.

One other paragraph that I want to mention:

There isn’t much sugar in the Amazon. But my next stop was the Cerrado, south of the Amazon, an ecological jewel in its own right. The Amazon gets the ink, but the Cerrado is the world’s most biodiverse savanna, with 10,000 species of plants, nearly half of which are found nowhere else on earth, and more mammals than the African bush.

I haven’t seen a lot of mainstream coverage of the situation in the Cerrado, but I did write about it in the renewable diesel chapter that I recently contributed to a book that is still pending publication. When proponents say that sugarcane isn’t grown in the Amazon, they are right. But the story is much more complex than that.

19 thoughts on “How Corn Ethanol Destroys Rain Forests”

  1. Obviously, we have to be careful how we adopt bio-fuels. But then, industrialization itself has been ruinous to the environment, and I don’t see anybody volunteering to go back to tee-pees and log cabins.
    The good news is that maybe Shell has figured out a way to make gasoline from biomass, not crops. Shell also says it can get shale oil for $30 a barrel, using minimally destructive techniques. And GM says the PHEV is two years away. Solar, wind and geothermal all close to viable.
    I have little doubt in the next 50 years we will see a more prosperous and cleaner planet.

  2. Glad to see that the implications of Searchinger’s work are sinking in — and this means that there isn’t very much low-GG biomass out there for the taking. If we disallow any biofuels that impact food production — and take into account the much greater food production we’ll need for a growing population of increasingly carnivorous humans — the quantity of biofuels we can make from waste and “marginal” land is pretty small.

    So for long-term answers to peak oil and global warming, we must look to efficiency (which is generally much cheaper than the sexier supply-side approaches) and true renewables — solar, wind, geothermal, tidal, etc. If we put a fraction of the 100’s of billions being sunk into biofuels into these techs, we’d be *much* better off in the long run.

    Slightly OT: Though it doesn’t promise big energy output, I do think that biochar is an interesting bio-energy route, with its promise of C sequestration and soil enhancement — as all this biofoolery is happening against a background of accelerating soil degredation around the world.

  3. “I have little doubt in the next 50 years we will see a more prosperous and cleaner planet.”

    I’m with you Benny. I think the tipping point into the Solar Age is $300 per barrel oil. At that point,any alternative will be preferable. The earth gets 174,000 terawatts of solar energy each year. The planet only consumes 15 terawatts of energy each year. Battery technology is improving by leaps and bounds. Solar cell costs are still declining. At some point in the future,drivers will pull up to electric vending machines,instead of gas pumps. Like yourself,I’m looking forward to it. I just hope I live long enough to see it.

  4. Maury-

    you are talking to a bald-headed who can remember JFK getting elected.
    But I still expect to see one of two things:
    Widescale adoption of PHEVs, fueled by solar, geothermal, wind, nukes, clean coal etc., or ….

    a collapse in oil prices……

    I don’t think we will ever see $300 oil….there is gobs of oil out there now, the only shortage is oil in stable nations…..but demand is falling….

    $120 tops…then a long, long slide? Who knows….

  5. Cheaper oil would be disastrous Benny. It would put off cleaner alternatives for years again. I’m fairly convinced we’ve hit peak oil. I got convinced when Saudi Arabia told Bush no when he asked them to pump more oil. I don’t think they can. If the world hit peak oil,production will gradually decline. We can offset some of the decline with tar sands,coal,and oil shale,but I’m not sure that would be enough to meet demand. It would take some serious demand crushing to create a surplus under those conditions. Can’t see it happening without a severe worldwide recession. I’d be surprised if we ever see sub-$80 oil again. $200 won’t take long at all at the rate oil is climbing. Next year maybe?

  6. Aldo V da Rosa’s textbook Fundamentals of Renewable Energy Processes has chapter 13 on biomass with some figures worth knowing. For example, he writes “At present, 75 tons of raw sugar cane are produced annually per hectare in Brazil. The cane delivered to the processing plant is called burned and cropped (b&c) and represents 77% of the mass of the raw cane. The reason for this reduction is that the stalks are separated from the leaves (which are burned and whose ashes are left in the field as fertilizer) and from the roots that remain in the ground to sprout for the next crop. Average cane production is, therefore, 58 tons of b&c per hectare per year. Each ton of b&c yields 740 kg of juice (135 kg of sucrose and 605 kg of water) and 260 kg of moist bagasse (130 kg of dry bagasse). Since the higher heating value of sucrose is 16.5 MJ/kg, and that of the bagasse is 19.2 MJ/kg, the total heating value of a ton of b&c is 4.7 GJ of which 2.2 GJ come from the sucrose and 2.5 from the bagasse. Per hectare per year, the biomass produced corresponds to 0.27 TJ. This is equivalent to 0.86 W per square meter. Assuming an average insolation of 225 W per square meter, the photosynthetic efficiency of sugar cane is 0.38%.”

    And sugar cane is considered once of the best energy crops!

    He goes on to say, “the 135 kg of sucrose found in 1 ton of b&c are transformed into 70 liters of ethanol with a combustion energy of 1.7 GJ. The practical sucrose-ethanol efficiency is, therefore, 76% (compare with theoretical 97%). One hectare of sugar cane yields 4600 liters of ethanol per year (without any additional energy input because bagasse produced exceeds the amount needed to distill the final product). This however does not include the energy used in tilling, transportation, and so on. Thus, the solar energy-to-ethanol conversion efficiency is 0.13%.”

    For comparison, the solar-to-electricity conversion efficiency of a Stirling dish is around 30%. Thus it takes 230 times as much land to produce energy in the form of sugar cane ethanol as it does to produce it in the form of electricity.

    Of course, ethanol energy cannot be used as efficiently as electrical energy to power transportation. That factor of 230 could easily become two or four times greater if that is factored in.

  7. The U.S. currently drives 9300 miles per person per year, or 2.7 trillion vehicle miles per year (VMT). In 2050 the U.S. population is expected to be 420 million, so the VMT will be 3.9 trillion miles, assuming that per person miles does not increase further (it has been).

    Let’s say in 2050 we are getting a fleet average of 40 MPG from gasoline in internal combustion hybirds (e.g. the Prius of 2050 is getting 60 MPG). Therefore we will need 98 billion gallons of gasoline to fuel this travel (compare to 140 billion gallons of gasoline).

    Unfortunately, gasoline is not an option in 2050, so let’s consider E85. The LHV of ethanol is 80.2 MJ/gal, and gasoline is 121.3 MJ/gal, so the LHV of E85 should be about 86 MJ/gal. So it should take about 40% more gallons of E85 compared to gasoline because of the lower energy content. But E85 allows engines to operated at higher compression, which improves efficiency. Let’s use 25% more E85 than gasoline, and then our requirement is 122 billion gallons of E85, which is a blend of 104 billion gallons of ethanol and 18 billion gallons of gasoline.

    In January, Schmer et al published yields of switchgrass in PNAS as 7100 kg/hectare/yr. At 0.38 L/kg for cellulosic ethanol production, this is 2700 L/ha, or 712 gal/ha. 104 billon gallons of ethanol per year therefore requires 145 million hectares of land, or 562,000 mi^2.

    The non-Alaska land area of the U.S. is 3,130,800 mi^2, so this requires 18% of that land area. (I am presuming that Alaska won’t be suitable for growing switchgrass, but of course if we don’t stop global warming, it may someday be the only place we’ll be able to grow it.)

    Oh, and if that weren’t bad enough, consider that greenhouse gas emissions from E85 are ony 64% lower than from gasoline, according to the ANL GREET model. We need them to be at least 85% lower by 2050, and headed to zero shortly thereafter.

  8. Here’s the above VMT calculation redone for solar-powered BEVs for comparison. 3.9 trillion miles per year at 300 Wh/mi is 1172 TWh/yr. Given the 92% efficiency of the grid, we need 1274 TWh at the solar farm. The Stirling dish solar farm at Victorville is expected to generate 1780 GWh/yr on 1800 ha. We therefore need 1,288,00 ha, or 4,973 mi^2.

    4,973 mi^2 or 562,000 mi^2: which would you choose?

  9. KingofKaty,

    Google is very good at green washing.

    They could have made a point by turning off youtube off for an hour.

    And to increase the irony here I am slagging google on a google owned platform.



  10. Here is a justification for the 300 Wh/mi I used in my last comment. This is not the value for some futuristic battery electric vehicle (BEV), but rather old technology. My family has once such vehicle, purchased in 2002, currently with 77,000 miles on the odometer. It is a boxy SUV, not a sleek sedan such as the Prius. Thus it is probably fairly representative of the fleet average (which would include both larger SUVs and also much smaller sedans).

    Go to the EPA fuel economy website, click on Compare Side-by-Side, 2002, Toyota, and finally RAV4 EV. Note the EPA ratings of 27 kWh/100mi city, 34 hwy. This is 270 Wh/mi and 340 Wh/mi respectively. Apply the typical 55% city, 45% hwy weightings and you get 301.5 Wh/mi.

    In comparison, the current vehicle fleet, at about 22 MPG, is a long way from the 40 MPG I assumed above. For the fleet to reach 40 MPG by 2050 requires new vehicle sales to reach 40 MPG by 2030 (it takes a long time to change the fleet). The current CAFE targets are 35 in 2020, so 40 MPG in 2030 seems possible.

  11. Chief scientist revolts over biofuel legislation
    On Monday, Bob Watson, chief scientist at the UK’s Department of Environment Food and Rural Affairs, called into question the idea of switching to biofuels. This follows the publication of studies showing that more carbon is emitted in producing some biofuels than is saved by burning them in place of fossil fuels. Former UK chief scientist David King also denounced biofuels that displace food crops and tropical rainforests.

    … The UK government is awaiting a report in June from its Renewable Fuels Agency before considering a change in policy. In the meantime, the UK must comply with European legislation. That means from 15 April, fuel suppliers must ensure that biofuels account for at least 2.5 per cent fuel in the pumps, rising to 10 per cent by 2020.

  12. Mr. Killian, it’s common to see RAV4-EV consumption numbers of 300 Wh/mile or even less, but this is usually measured at the battery’s DC output. NiMH is only about 70% efficient, so this translates into 400 Wh/mile at the AC wall plug. SoCal Edison tracked five RAV4-EVs in their fleet, this PDF file shows average AC wall plug consumption was 400 Wh/mile (page 3).

    Modern lithium batteries can achieve 90-95% efficiency and are lighter, which reduces rolling resistance. 300 Wh/mile for a small SUV is achievable but not yet demonstrated in the real world. Similary, 250 Wh/mile is a good target for a mid-sized sedan.

  13. doggydogworld, the SCE data is for an earlier incarnation of the RAV4-EV. Toyota increased efficiency since then, as can be seen by comparing the 2000 and 2002 models at

    One RAV4-EV driver posted a note that he kept a 1000-mile log based on a separate AC kWh meter and got 310 Wh/mi, which is not enough data to say that is the answer, but enough to indicate that the SCE data is much too high for the later model years.

    If you have a reference to show that the EPA’s test procedure is based on the battery output rather than the plug, I would like to see it. I looked, and found nothing either way. I have submitted a query at their website, but I doubt that I will get an answer.

    Also, I know that NiMH batteries state of charge decreases from 100% to 90% in the first 12 hours after charging, but as most EV drivers start their charge at night using a timer, the charge completes only a short time before first. Thus this 10% efficiency loss should not be assumed in everyday use.

Comments are closed.