Posts Tagged ‘ethanol’

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Nobel Prize winning biochemist says ALL biofuels are “nonsense.”

February 25, 2012

Similar posts from ClimateSanity
Taking Measure of Biofuel Limits 9/24/2009
Biofuels Leading to Disasters 12/28/2011

Hartmut Michel

Hartmut Michel

Hartmut Michel won the Nobel Prize in Chemistry for his work on photosynthesis.  So, it is fair to say that he knows a thing or two about energy transport and storage in plants.  Today he is director of the Molecular Membrane Biology at the Max Planck Institute for Biophysics.

He recently penned an editorial in Angewandte Chemie International Edition in which he hammered the use of biofuels for alternative energy.  Note that Angewandte Chemie International Edition has the world’s highest impact factor of all chemistry journals.  His simple but pointed criticism condemns all varieties of biofuels and supports my previous posts on this subject.1, 2

The problem is the inherent inefficiency of photosynthesis.  He points out…

“The photosynthetic pigments of plants can only absorb and use 47%(related to energy) of the light of the sun (“photosynthetic active radiation”). Green light, UV, and IR irradiation are not used…

Photosynthesis is most efficient at low light intensities. It is already saturated at 20% of full sunlight and 80% of the light is not used…In addition, high light intensities lead to photodamage of a central protein subunit of the photosynthetic apparatus…3.5 billion years of evolution have not been long enough to develop a mechanism for preventing the photodamage….

The dark reactions are limited by an insufficient discrimination between CO2 and O2 by the enzyme RuBisCO, which inserts CO2 into ribulose-1,5-bisphosphate. One third of the energy of the absorbed photons is believed to be required to remove the product of the O2 insertion…[and] photosynthesis depends on the availability of sufficient amounts of water, a condition that is not met during much of the day.”

Current biofuel technologies

Taken as a whole, conversion efficiency of sunlight to usable chemical energy in biofuels for commonly used technologies is extremely low.

“For German “biodiesel” which is based on rapeseed, it is less than 0.1%, for bioethanol less than 0.2%, and for biogas around 0.3%.”

But is it actually much worse than that when you consider

“… these values even do not take into account that more than 50% of the energy stored in the biofuel had to be invested in order to obtain the biomass (for producing fertilizers and pesticides, for ploughing the fields, for transport) and the chemical conversion into the respective biofuel.”

Michel confirms what I have pointed out before, biofuels of all stripes put a great burden on arable land.  He says…

“Taken together, the production of biofuels constitutes an extremely inefficient land use. This statement is true also for the production of bioethanol from sugar cane in Brazil.”

“Second Generation” biofuels

Some people hold out hope for “second generation” biofuels where the whole plant is utilized.  Michel explains that this is an illusion because the energy input for these types of processes in ever greater than for first generation processes.  For example…

“in the production of biodiesel by the Fischer–Tropsch process, hydrogen has to be added because syngas obtained from biomass contains insufficient amounts of hydrogen.”

More distant possibilities

“Hydrogen production by photosystem II would reduce the number of photons required by more than 50%.  However, this protein engineering task appears to be insurmountable at present.”

and

“Microalgae have been advertised as the ideal candidates for biofuel production. There are many unsupported claims about their efficiency, some even exceeding the theoretical limits of photosynthetic efficiency…the existence of photoinhibition and a poor RuBisCO will limit the advantages of microalgae together with the demands for growing and harvesting them.”

But biofuels will save us from CO2

Sorry, no.

“The production and use of biofuels therefore is not CO2-neutral. In particular, the energy input is very large for the production of bioethanol from wheat or maize, and some scientists doubt that there is a net gain of energy. Certainly the reduction of CO2 release is marginal.”

And

“Clearing rainforests in the tropics and converting them into oil palm plantations is highly dangerous because the underlying layers of peat are oxidized and much more CO2 is released by the oxidation of organic soil material than can be fixed by the oil palms…it would be even much better to reforest the land used to grow energy plants, because at a 1% photosynthetic efficiency, growing trees would fix around 2.7 kg of CO2 per square meter, whereas biofuels produced with a net efficiency of 0.1% would only replace fossil fuels which would release about 0.31 kg CO2 per m2 upon combustion!”

His conclusion

“Because of the low photosynthetic efficiency and the competition of energy plants with food plants for agricultural land, we should not grow plants for biofuel production. The growth of such energy plants will undoubtedly lead to an increase in food prices, which will predominantly hit poorer people.”

Read the entire editorial in context here (The Nonsense of Biofuels, Hartmut Michel, Angew. Chem. Int. Ed. 2012, 51, 2–4)

Here is a video of Michel making the same point.

His Noble Prize was for the determination of the three-dimensional structure of a photosynthetic reaction centre, as seen here

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Bad professors, BAD. The truth about “Eat the Dog”

October 23, 2009

IMG_0409-1Guest post from Cocoa the dog

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I am told humans are smart, but sometimes I wonder.   I was born back in ’02, and I have learned a trick or two in my 49 years.  But this old dog will never play the kind of trick that Brenda and Robert Vale are playing.  They are off by a factor of 20 when comparing the energy to power an SUV with the energy to power a dog.

Brenda and Robert Vale are professors at Victoria University in Wellington, New Zealand.  They are either complete mathematical boneheads, or they have simply realized that in today’s world there is no limit to the outrageous claims that they can peddle to other completely credulous humans.  They claim in their book “Time to Eat the Dog: The real guide to sustainable living” that I am an energy hdogs – worse than a gas guzzling SUV.  Here is their (il)logic, as reported in the New Zealand Dominion Post

The couple have assessed the carbon emissions created by popular pets, taking into account the ingredients of pet food and the land needed to create them.

“A lot of people worry about having SUVs but they don’t worry about having Alsatians and what we are saying is, well, maybe you should be because the environmental impact … is comparable.”

In a study published in New Scientist, they calculated a medium dog eats 164 kilograms of meat and 95kg of cereals every year. It takes 43.3 square metres of land to produce 1kg of chicken a year. This means it takes 0.84 hectares to feed Fido.

They compared this with the footprint of a Toyota Land Cruiser, driven 10,000 kilometers a year, which uses 55.1 gigajoules (the energy used to build and fuel it). One hectare of land can produce 135 gigajoules a year, which means the vehicle’s eco-footprint is 0.41ha – less than half of the dog’s.

Let me help my two-legged friends with their calculations.

Let’s compare the amount of land needed to generate enough biofuel to drive a Toyota Land Cruiser 10,000 km, to the amount of land required to feed a dog.  Let’s compare kibbles to kibbles.  In the case of the Land Cruiser grain may be converted to ethanol to power the vehicle.  Similarly, grain can be fed to animals to yield meat, which can be fed to the dog. 

Land Cruiser

My farm animal friends tell me that corn is the best grain for making ethanol.  In the US, where they grow a lot of corn, they got 371 bushels of corn per hectare in 2007. Each bushel of corn gives about 2.7 gallons of ethanol according to the USDA.  So that means each hectare of corn yields about 1000 gallons of ethanol.**

The humans at Toyota say that the Land Cruiser gets 13 miles (20.8 kilometers) per gallon in the city and 18 miles (28.8 kilometers) per gallon on the highway.  But that is when it runs on gasoline.  The energy content of gasoline is 115,000 BTU/gallon.  But for ethanol it is only 75,700 BTU/gallon.  So it takes about 50% more ethanol to get the same energy.***  That is, the Land Cruiser would only get 8.6 miles (13.8 kilometers) per gallon of ethanol in the city and 11.8 miles (18.9 kilometers) per gallon of ethanol on the highway.****  Let’s average it and call it 10.2 miles (16.3 kilometers) per gallon of ethanol for the Land Cruiser.

So it takes 613 gallons of ethanol to drive the Land Cruiser 10,000 kilometers.  That translates into 0.61 hectares of corn land. *****

Feeding a dog

Remember, a hectare of corn gave 371 bushels of corn in 2007.  A bushel of corn weighs 56 pounds (25.5 kilograms).  That is 20,776 pounds (9,441 kilograms) of corn per hectare.+

If you want to convert that corn into chicken meat, as the professors suggest, then according to the Agricultural branch of the Australia’s Department of Primary Industries, the conversion factor is about two kilograms of chicken feed to one kilogram of chicken liveweight.   That means that a hectare of corn would give about 10,388 pounds (4,722 kilograms) of chicken liveweight.  Dogs are not as fussy as humans, but even we don’t eat the feathers. We would only eat about 2/3 of the bird liveweight.  That fetches 6925 pounds (3147 kilograms) of edible meat per hectare.++

According to the boneheaded professors, a typical dog eats 164 kilograms of meat per year.  (I have a pretty good life – but I can tell you I don’t eat nearly that much. But I’ll play along anyway.)  That would require 0.052 hectares to produce.+++  They say that we also eat another 95 kilograms of cereals each year – or another 0.01 hectares worth of corn.++++  That sniffs out to 0.062 hectares worth of land to feed an overfed dog.

Conclusion

0.61 hectares to feed the soulless Toyota Land Cruiser.

0.062 hectares to feed your best friend.

That’s 10 times as much for the Land Cruiser than for me.  I could have sworn the professors said the dog required twice as much land as the Land Cruiser.  They were only off by a factor of 20.

Bad professors, BAD.  Don’t make me rub your nose in it.

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* (151.1 bushels / hectare) x (2.46 acres / hectare) = 371 bushels per hectare.

** (371 bushels)  x  (2.7 gallons/bushel) = 1006 gallons

*** 115,000 BTU  /  75,700 BTU  =  1.52

**** (13 miles / gallon) / 1.52  =  8.6 miles / gallon = 13.8 kilometers / gallon
**** (18 miles / gallon) / 1.52  =  11.8 miles / gallon = 18.9 kilometers / gallon

***** 10,000 kilometers / (16.3 kilometers / gallon) / (1002 gallons/ hectare) = 0.61 hectares

+ (371 bushels/hectare) x (56 pounds/bushel) = (20,776 pounds/hectare) = (9443 kilograms/hectare)

++ (20,776 pounds/hectare) x (1/2)  x  (2/3) = (6925 pounds/hectare) = (3147 kilograms/hectare)

+++ (164 kg of meat/dog) / (3147 kg of meat/hectare) = (0.052 hectares/dog)

++++ (95 kg of corn/dog) / (9,441 kg of corn/hectare) = (0.01 hectares/dog)

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Taking Measure of Biofuel Limits

September 24, 2009

The current edition of American Scientist has a very good article on the fundamental biological limits of governing the production of biofuels.  Taking the Measure of Biofuel limits, by Thomas Sinclair addresses the two obvious limiting factors, light and water, and the perhaps less obvious limiting factor of nitrogen availability in the soil.

Thomas R. Sinclair is a professor in crop science at North Carolina State University with a Ph.D. from Cornell.  He specializes in the relationships between plant physiology, the environment, and crop yields.  He has edited several books as a Ballard Fellow at Harvard University.

Sinclair sets the stage by pointing out..

The U.S. Energy Independence and Security Act calls for 144 billion liters of ethanol per year in the U.S. transportation  fuel pool by 2022.  That equals 25 percent of the U.S. gasoline consumption today.  No more than about 4o percent is to be produced with maize, an important food and export crop.  Non-grain feedstock is supposed to provide the rest.

Before nations pin big hopes on biofuels, they must face some stark realities, however.  Crop physiology research has documented multiple limits to plant production on Earth.  To ramp up biofuel crop production, growers must adapt to those limits or find ways around them.  Such advances may not be as simple a some predict.  Plants and their evolutionary ancestors had hundreds of millions of years to optimize their biological machinery.  If further improvements were easy, they would probably already exist….

Plants cannot be grown without three crucial resource inputs: light, water, and nitrogen.  Each of these inputs is needed in substantial quantities, yet their availability in the field is limited…[T]he close relationship between the available amounts of these resources and the amount of plant mass they can produce – not human demand – will determine how much biofuel the world can produce.

Light

Sinclair considers the conversion efficiency of sunlight  and CO2 to sugars, which ultimately fuel the building of starch, cellulose, protein and lipids, for C3 plants (95% of all of Earth’s plants, but not highly CO2 fixation efficient) and the more efficient sugar-making C4 plants (corn, sugar cane and sorghum, for example).  He points out that “After hundreds of millions of years of evolution, these systems [for converting solar energy into the chemical energy of sugars] are highly efficient within the physical and thermodynamic constraints of photosynthesis and plant growth.”  Not much room has been left for improvement.

Bio-engineering advances may increase yields a little, but they cannot overcome the limits of the sunlight to sugar conversion ratios.  After the numbers are crunched he reveals that if the U.S. is to reach its biofuel goal of 58 billion liters of ethanol grown from corn (40 percent of 144 billion liters), it would require an additional 15 million hectares planted.  Similarly, the remaining 86 billion liters made from non-corn C4 grasses, which are not nearly as efficient as corn for this purpose,  would require at least an additional 48 million hectares.

Water

It may be obvious that in areas of limited water supply, plant growth will be limited by the amount of water available.  As plants transpire water out through their leaves, the rate of transpiration is:

T = G x VPD/k

where T is the transpiration (g/m2)
G is the plant growth (g/m2)
VPD is the Vapor Pressure Deficit, or the difference in the saturated water vapor pressure of air inside the plant leaves and the water vapor pressure of the outside atmosphere
k is a plant specific constant

The difference in the vapor pressure inside and outside a leaf (VPD) is what controls the rate of water loss through the stomata.  The VPD is large in arid regions because the vapor pressure of the water in the atmosphere is low. 

For a given environment  the VPD cannot be controlled – it is what it is.  So the only way for a plant to affect the transpiration, and thus prevent itself from drying out and dying in a arid environment, is to close down its stomata to reduce water loss.  But this also reduces the flow of CO2 into the leaves and O2 out, and consequently reduces or stops the plant’s growth.  There is no magic to get around this.  Sinclair  says…

“Despite claims that crop yields will be substantially increased by the application of biotechnology, the physical linkage between growth and transpiration imposes a barrier that is not amenable to genetic alteration.”

Under these circumstances the plant mass growth is nearly linear with water transpired.  So as more arid regions are put into crop use either crop yields per hectare will be lower, or the amount of irrigation will be higher.  This leads to the production of biofuels at the expense of aquifer depletion.

Nitrogen

Sinclair repeatedly points out that to be economically viable, biofuel crops must yeild at least 9 tonnes of plant mass per hectare of crop.  For C3 and C4 type plants this 9 tonne minimum requires the removal of 166 kg and 118 kg or nitrogen per hectare, respectively.  But, “Expectations for cellulosic yields are sometimes double or triple the 9-tonne-per-hectare yield” required for economic viability.  So, nitrogen removal from the soil will sometimes be double or triple also.   Some of this nitrogen is replaced by plant debris that is left behind and some comes from thunderstorms and some from organisms that fix atmospheric nitrogen.  But these sources are not enough to replace all the nitrogen that is removed with every harvest, and the available nitrogen will be less every year.  Sinclair explains…

“Although this decrease rate is usually small when compared to all the original organic matter in the soil, a cropping practice dependent on a continuous withdrawal clearly is not sustainable…  Nitrogen fertilizer of annual biofuel crops will inevitably be needed once soil organic matter decreases to levels limiting plant growth.”

Sinclair’s conclusion

Taking the limits of light, water and nitrogen in to account, for corn he concludes…

“The equivalent of 40 percent of today’s U.S. maize crop will be required to ethanol production while other domestic and export demands for maize also must be met.”

And for cellulosic derived ethanol he concludes that up to…

“50 million hectares of new land must be brought into high and sustainable agricultural production to achieve the required yields… it would be the most extensive and rapid land transformation in U.S. history… [L]and used for cellulosic feedstock must be in regions with sufficient rainfall to achieve needed yields.  The amount of water transpired by those crops could be large enough to influence the hydrologic balance of farming regions.”

and for in general…

“I]ncreased nitrogen supplementation required for the new crops will result in more nitrogen leaching into natural waterways…”

My final words

Sinclair indicates that between corn and other plants for ethanol, the U.S. may have to put as much as an additional 65 million hectares into crop production (15 million hectares for corn and 50 million hectares for other biofuel crops) to  generate 144 billion liters of ethanol.  This would replace only 25% of our gasoline usage.

How big is 65 million hectares?  It is the same as 650,000 square kilometers, and about the same as 160 million acres.  To put this in perspective, this is more than 10 times the acreage of corn planted in Iowa in 2007.   It is more than 150% of the corn acrage planted in the entire United States in 2007.

Look at the figures below.  The first image is from the USDA Census of Agriculture for 2002, and it shows the acreage planted in corn for grain in the United States that year.  Each dot on the map represents 10,000 acres.  To achieve 144 billion liters of ethanol we could need an additional 160 million acres of of corn and other crops, or more than 10 times the amount of corn acreage planted in Iowa.  The second figure shows the corn acreage of Iowa multiplied ten fold and added to the map of the United States.  This should give you some idea of the unprecedented agricultural multiplication that would be needed to satisfy the U.S. Energy Independence and Security Act.

corn acres

new crop area 2
Cartoon of ten times the corn acreage of Iowa added to the US. This gives some idea of what may be required to satisfy the U.S. Energy Independence and Security Act requirement of 144 billion liters of ethanol to replace 25% of U.S. gasoline usage.

Let’s face it – this ambitious goal of 144 billion liters of ethanol per year from biofuels is a very bad idea.  Our most precious resources are the land, water and resources for making fertilizer (which is primarily natural gas for nitrogen fertilizers).  The dumbest thing we can do is deplete our soil and aquifers, pollute our water with extra nitrogen fertilizer, and waste our natural gas to make ethanol.  If you think living with a shortage of gasoline is rough, try living with a shortage of food.

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