Monday, November 8, 2010

Beyond Corn Ethanol: Bioproducts from 'Garbage'

Though algae has great promise to secrete oils or be biomass itself,  algae always seems to about “five years away,” according to Dr. William J. Orts of USDA’s agriculture research service  in Albany, CA who spoke at UC Davis Energy Institute this past week.

Seemingly to prove his point, one of the large oil companies has been running a TV advertisement, featurng a middle-aged researcher:

“It is was 1975 and my professor at Berkeley asked if I wanted to change the world.   I said sure.  And he said, ‘Let's grow some algae’.”

Dr Orts talk, “Agriculturally Derived Biofuels and Bioproducts: Going Beyond Corn Ethanol” began with corn ethanol summary: Though it is in production now, enjoys a $0.51 per gallon subsidy  and “we know how to do it,”   it suffers from several drawbacks, including a bad carbon footprint when all the fertilizer use and transportation is factored in.  Ethanol is also corrosive, so can not be put into pipelines, and there is not enough of it to make a real dent in US demand for transportation fuels.

Much research is now focused on second generation biofuels.  Energy crops are “very hot now”, he said, for example switchgrass.    Dr. Orts outlined the basic line of attack on cellulosic biomass (think: harder to degrade corn or rice stalks, not the corn) by pointing out that  we should learn from anything that ‘eats wood’, from fungus to cows.  

Like algae, it is not so easy.   Whereas corn starch breaks down with just 2-3 enzymes, heavy cellulosic materials can need 16.  The goal for many researchers is finding the right “3-in-1” kind of sauce with the right genetic-modified material and optimized enzymes to seek out and attack the chemical and biological weaknesses of cellulose.

But Dr. Ortis then turned to one of his favorite approaches which can work now:  garbage.  Garbage, or municipal solid waste ( MSW), is about 40% cellulosic.    MSW - the waste,  plastic bottles and all - can be sorted,  ‘cooked’ in the right environment  (temperature, enzymes, etc) to yield biofuel (ethanol) or biogas (ex: natural gas) or even paper for paper plates.  (There are hopes of this new bioproducts industry will even replace petroleum  in the manufacture of man-made  fibers, polymers or even the medicines that we have become so used to. )

The city of Salinas is planning   a project with uses pre-treatment and sorting MSW.   The equipment then “cooks” it and  creates ethanol.   It avoids the landfills completely.  And, it can be done now.


Thursday, November 4, 2010

China’s Farm Waste to Energy Programs

As part of an ambitious farm waste-to-energy program, the Chinese government provides rural households with an anaerobic digester as a way to provide inexpensive cooking biogas and heat while also removing farm animal and human waste, according to Dr. Xiujin Li of Beijing University of Chemical Technology, who visited UC Davis today with a Chinese delegation.

China began a program for anaerobic digesters in 1975, but many suffered leaks and were of poor quality and were phased out.    Today, some 35 MM of these rural digesters many made from newer durable materials now exist, up from 10 MM in 2000.  Many are the size of a couple of refrigerators and buried underground on a farm.  The price is $400, beyond reach of most Chinese farmers but paid for under the government program.  Dr. Li mentioned that Americans have asked him where to purchase.

In larger Chinese communities or larger farms,  such as a commercial chicken farm, the Chinese government has offered since 2005  a second program for  much larger anaerobic digesters  to convert the waste into biogas, fuel for electricity or natural gas for vehicle fuel.  The government provides just over $700 MM annually for the equipment and the maintenance of these larger, more complex biodigesters, in which Dr. Li said  support  is “only a phone call away.”    Local governments must then commit an equal amount of the funding. [update: Here is an excellent video by Amy Zeng about biogas production in Kunming]

China also a problem with dry, crop residue.   Annually, China produces 700 MM tons of dry rice, wheat, corn  waste (the stalks), half of which is  burned in open fields.   This dry waste has a high lignocelluloisic component, making it difficult to biodigrade.   Dr. Li described several university research efforts  in China to improve the biogas yields and reduce the time to produce.  One promising approach is pre-treating with sodium hydroxide, other research effort range from fungus to various reactor designs.  

What works in the lab, of course, may not work in the fields.  This is true everywhere, but it is particularly important to realize that in a developing country, like China, development is uneven.   The best features of a modern society can often be  juxtaposed with the face of a poor, less developed society.   In other words, Dr. Li stressed technologies used in anaerobic digestors must not only be low capital, cost-effective but also reliable and must scale easily.  

Still, some lingering questions remain, do the small biodigesters leak and contaminate underground water?   Who decides which villages and farmers have access to the government’s financial programs?

One way answer is to encourage collaboration with foreign scientists and this was just one purpose of Dr. Li visit, who had obtained his Ph.D from UC Davis.

(Remark: Dr. Li’s talk was about biogas.  China limits the use of food crops for ethanol, but is working with  jatropha )

Additional information:

Biogas in developing countries background