Biomass Chemistry
A Newly Electric Green – Sustainable Energy, Resources and Design
Thursday, June 23, 2005
"Peak Oil" continues its march to memetic dominance, and a greater number of pundits and politicians not previously known for talking about the environment have started to ask what happens when oil runs out. For many who embrace the "Peak Oil Is Here" idea, the answer is simple: chaos, because petroleum is at the heart of much of industrial and agricultural production, not just transportation.
But that's not the only scenario. There has been quite a bit of research into alternative means of producing the materials we now make using oil. Biomass is the top candidate for oil equivalents, and indeed biodiesel has been getting more attention of late as a renewable and low-net-carbon method of fueling vehicles, both by renewable energy advocates trying to move away from fossil fuels and by researchers trying to improve the efficiency of biodiesel production. Biomass is also being used as an experimental feedstock for chemicals now requiring petroleum. And by stretching the definition of biomass a bit, even fertilizer -- a favorite of the apocyphiles -- can be made without fossil fuels.
Converting biomass to biodiesel is not terribly efficient -- depending upon the base plant, it can sometimes only produce marginally more energy than is used by the conversion process. But researchers at the University of Wisconsin have come up with a new method of biofuel production that is significantly more efficient than previous technologies (and is double the efficiency of current ethanol production). This development is able to convert the carbohydrates in plants -- about 75% of the dry weight -- into fuel. In an interesting bit of biomimicry, the process is similar to the way in which carbohydrates are used in the body to produce energy:
"It's a very efficient process," says Huber. "The fuel produced contains 90 percent of the energy found in the carbohydrate and hydrogen feed. If you look at a carbohydrate source such as corn, our new process has the potential to creates twice the energy as is created in using corn to make ethanol."
About 67 percent of the energy required to make ethanol is consumed in fermenting and distilling corn. As a result, ethanol production creates 1.1 units of energy for every unit of energy consumed. In the UW-Madison process, the desired alkanes spontaneously separate from water. No additional heating or distillation is required. The result is the creation of 2.2 units of energy for every unit of energy consumed in energy production.
Although the UW process takes many steps, the researchers are confident that it can be improved quickly. The bigger roadblock to implementation is the need for biofuel refineries:
The key is building biorefineries that balance the energy. A refinery balances energy requirements of each process with those of other processes and the chemical intermediaries of each process are either separated as final products or used elsewhere in the refinery, said Dumesic.
As noted, biomass can be used to replace more than fuel. Green Car Congress notes that chemical company Codexis and Cargill has announced a new process that converts corn sugars to a "chemical intermediate" called 3HP.
The new process will utilize very low-cost, clean agricultural feedstocks instead of petroleum to produce 3HP. 3HP is a key intermediate for several commercially important chemicals. The chemicals that can be produced from 3HP include acrylic acid, acrylamide and 1,3 propanediol. Acrylic acid and its derivatives are used to create a wide range of polymer-based consumer and industrial products, such as adhesives, paints, polishes, protective coatings, and sealants. This new process is cheaper and more environmental friendly than the old process that uses petroleum as a feedstock.
[...] Sugars and lipids from agricultural crops can be used in many products, replacing increasingly expensive oil and natural gas, which are currently the main feedstocks of the chemical industry [...]
Undoubtedly, more work needs to be done to make the resulting chemical products more environmentally friendly, but the point here is the ability to find alternatives to petroleum feedstocks.
But the loss of chemical production ability isn't the chief fear of those who say that oil production has nowhere to go but down. Rather, the inability to create nitrogen fertilizer for industrial farming is what they worry about most.
First, a quick note: as we've explored at length, industrial farms are not the only way or the best way to provide food for the world's citizens. There are healthier, more environmentally-friendly ways of growing food not requiring masses of petroleum fertilizer or pesticides. That said, absent a global revolution in thinking, industrial food production will likely continue for quite a few more years, and industrial agriculture techniques may turn out to be necessary to maintain food production during serious climate disruption.
So what's the biomass-based alternative to using petroleum for fertilizer?
Algae.
Engineer-Poet at the Ergosphere breaks it down. Algae can be used to produce hydrogen, and hydrogen can be used to "fix" nitrogen. With the hydrogen production operating a mere 1% efficiency, a hectare of hydrogen-generating algae could produce the nitrate to fertilize around 20 hectares of agricultural production. That same hectare could fertilize 200 hectares if H2 generation efficiency is brought up to the 10% thought possible.
Moreover:
If 10% efficiency can be achieved, the hydrogen production goes up to 38 tons/ha/year (1.55 MWh/ha/yr) and it can become the basis of a general energy business. If crop wastes such as corn stover and wheat/rice straw are used as carbon inputs and have a general chemical formula of (CH2O)n, addition of H2 is all that is necessary to produce methanol (CH3OH). If the process can use the inputs with 100% conversion efficiency, 2 grams of hydrogen plus 30 grams of carbohydrate yields 32 grams methanol; 38 tons of hydrogen becomes 608 tons of methanol (about 203,000 gallons, holding the energy equivalent of 122,000 gallons of gasoline). At this level of production, inputs of crop waste are probably the limiting factor; long before this level was reached, the fuel production would satisfy all needs for cultivation.
Conclusion: it is not only possible to generate all required nitrogen fertilizer from solar energy using known processes or slight improvements, at the limit they could lead to large-scale production of biofuels from crop wastes. All it requires is hydrogen.
Algae farms may not be quite a sexy as fields of corn or soy, but may well be far more important.
The use of biomass to replicate the services provided by petroleum walks a fine line. As noted, these replacement processes allow the continued use and/or production of aspects of modern life that could by no means be considered sustainable. It's possible that a Peak Oil crisis could drive the adoption of far more sustainable methods and materials; unfortunately, it's also possible that a peak oil crisis could drive the onset of greater global conflicts, starvation and chaos.
I don't look at these developments as being permanent substitutes for sustainability, I see them as transition technologies. Work on improving the efficiency and utility of the more sustainable practices will continue, and -- as I fully expect -- when they are recognized as being demonstrably better, large-scale adoption will follow. A world of Peak Oil crisis and conflict is far less likely to let us get to that point.
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