Comparing Different Biofuels Approaches
When we consider biofuels a key criteria is what the net carbon gain and energy gain including all the processes to collect, process and then utilize the energy in that particular system. Its a good exercise to consider the many possible angles and variables when evaluating the different aspects of various competing and complementing approaches.
Biofuels will have a role to transitioning our society towards sustainable energy systems and yet the fundamental reality is that we already use too much of the world’s biomass and this is the major reason why we are losing biodiversity. We also need to consider the impact of using prime agricultural lands to produce energy when there is possible risk of a global food shortage. Other issues to consider is will there be enough water to sustain these agricultural lands?
Vinod Khosla Ethanol - Now when we consider corn ethanol it is very debatable that there is really a net gain because of all the energy required to harvest the corn and then process it. Sugar Cane is much better not just because the crop is more efficient in harnessing CO2 and solar energy into plant mass but because it only grows in tropical and subtropical climates where the growing conditions are much better. To address this many such as Vinod Khosla are advocating and investing in plants to produce Cellulosic ethanol
According to Wikipedia, there are at least two methods of production of cellulosic ethanol (see “Production methods”, below):
- Cellulolytic method: hydrolysis followed by fermentation of the generated free sugars.
- Gasification, which produces synthesis gas that can be converted to ethanol by fermentation or thermochemical catalysis (e.g., the Fischer-Tropsch process).
Jim Fournier’s Latest Venture with Biofuels – www.WoodGas.com, Biomass Energy and Carbon Corporation and http://biomassenergyfoundation.org are companion. These sites highlight a similar approach except that it is more of a biorefinery approach in which ethanol would be just one of many possible options for fuel and refinery products production. Its worth noting that one of the scientists that Jim is working with wrote a paper critical of the “Hydrogen Economy” here. Interesting to note that one stated goal and indeed one of the R&D focuses at Eprida was to produce pure hydrogen.
“Biomass Energy & Carbon develops biomass gasification technologies that produce clean producer gas streams for electrical and thermal energy as well as oxygen blown gasification systems that produce synthesis gas as a feed stock for catalytic gas-to-liquid fuel production. Future designs will also sequester carbon in the form of agricultural charcoal, thereby producing carbon-negative energy from biomass. “BEC draws on the experience of Dr. Tom Reed and Agua Das Ellis who together have over sixty years of experience in biomass gasification.”
Reinhold Ziegler & The Ed Burton Company – Reinhold Zielger working with Ed Burton at the Ed Burton Company see Fast Gas is planning on using “Fournier Reactor” to produce syn gas to power Combined Heating and Power gen-sets. Reinhold has a nice exec summ here about his work.
This is actually similar to what Danny Day is doing at Eprida (although Eprida made the case for final stage hydrogen conversion). One of the novel aspects of this approach is that it is designed for portability. That is it is designed for celluloise type feedstocks (husks, trees and woody plant/crop residues). So the problem with high fuel loads in the West is a potential opportunity for integrated biofuels production. I could envision the whole systems as an integral unit in a series of flat bed tractor trailers with:
- Modular living units for the workers
- Offices
- Equipment shed including the collection vehicles and shedding implements for the biomass
- Gasification and combined heating and power unit (to heat the living and office unit and provide hot water).
We could even see this as something that could be developed as a preventative tool to clean up high risk areas and possibly even when the fires are nearby and at risk of spreading.
The ZERI Approach: Biogas & Integrated Farming – One advantage of biogas as a potential source of bioenergy is that it is simply letting the bacteria do the work of producing energy that would have been naturally in nature. Most other biofuels approaches (including the ones mentioned above) use the “heat beat treat method” (Janine Beynus’ term describing the traditional industrial methods of manufacturing). However biogas is best utilized in the processing of soft plant and animal residues as compared to celluosic ethanol which works well with woody plants, husks and trees.
The utilization of biogas has become a common practice in China. This was combined with what for many thousands of years was common practice there – the use of manure and humanure as fertilizer – night soil. Most recently the Chinese came up with an advanced agricultural system that blends modern and indigenous Chinese agricultural approaches to create integrated farming systems (Chinese Ecological Agriculture or CEA). The larger application of this integrated approach in China is called the Circular Economy and is being pushed by a group called Indigo Development.
