Chapter 7: Other Uses for Biomass
This paper has focused essentially on the use of biomass for fuel, mainly for transportation fuel. However, there are other competing uses of biomass that offer a different set of costs and benefits than liquid fuel production
Another alternative use of almost any of the feedstocks mentioned here – corn, wheat, wheat straw, potatoes and others – would be to produce biogas rather than liquid fuels. Biogas is a mixture of methane and other gases, which is produced from the decomposition of biomass in anaerobic conditions. At its simplest, this involves dumping biomass in a digester, or large pot, and waiting for it to rot. While high-efficiency biogas production is not that simple, anaerobic digestion requires fewer inputs of capital, heat or energy than either ethanol or biodiesel production. Moreover, in terms of the usable energy value, biogas production seems to produce substantially more usable energy per acre than either ethanol or biodiesel.121 Once generated it can be purified and fed into the natural gas grid, burned for heat or electricity, or even compressed for use in compressed natural gas (CNG) vehicles.
While the focus on liquid fuels in this country has drawn attention away from producing biogas from traditional energy crops, biogas has been expanding rapidly in Europe (in Germany it is the fastest growing form of renewable energy).
Because of the lack of fossil fuel inputs into production and the high level of energy usable compared to liquid biofuels, biogas produces relatively greater GHG benefits for any feedstock than what was discussed for liquid fuels.
7.2 Biomass Electricity
As can be gleaned from the preceding discussions of net energy, it is more efficient to burn or gasify biomass directly to produce electricity because no costly intermediate conversion steps are needed. And, unlike cellulosic ethanol production, biomass power is an established technology that is already in use across the US. In fact, Oregon already has biomass power plants using wood wastes.122
Although biomass-generated electricity does not displace petroleum the way biofuels do,N electricity is likely to become much more important as a transportation fuel in the future. It is generally agreed that the best near-term environmental option for cars are plug-in hybrids, which can run both off electricity from the grid and use conventional liquid fuels. Using biomass energy to power electric or plug-in hybrid electric vehicles, even if gasoline was still used, may be one of the most efficient ways to reduce GHGs and fossil fuel use.
While this paper does not deal with the economics of biomass, the cost of getting bulky cellulosic feedstocks to processing facilities is one of the greatest hurdles to biomass energy. Because energy feedstocks need to be cheap enough to compete with gasoline there is little margin for biofuel producers to pay more to compete with other higher-value uses for biomass as well. This is particularly true in the case of wood products, where the vast majority of mill wastes go to low-value products like fiber board, which are still more profitable than if they were sold as biomass for energy. However, there is growing interest in using biomass to create a range of chemicals, plastics and other products that are currently derived from petrochemicals.
Since about 16% of US oil consumption goes to producing these products, there is still a huge potential for displacing petroleum and reducing pollution and GHGs. In fact, many bio-refineries may be able to produce ethanol or other biofuels as well as a range of other chemicals and products. Also, because many of these co-products are valued more highly than fuel, “bio-refineries” may be able to pay for more to get biomass out of the woods and the fields than could a straight ethanol producer, for example.
|Policy Recommendations - Bio-products:|
|While few technologies to produce chemicals, plastics and other products from biomass have been commercialized, state policy should encourage the development of these bio-based industries and not become exclusively focused on biomass energy production. For example, Oregon BEST, the Bio-Economy and Sustainable Technologies Research Center that is being developed in the Oregon University System, should research commercialization of these safer, non-toxic alternatives to petroleum-based products.|