A Renewable Energy Access (REA) article summarized a new report, titled "Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply," published by ORNL, determined that 30% of our petroleum consumption could be replaced with biomass fuels.
In the REA article, Bob Perlack, co-author of the report was quoted as saying "We wanted to know how large a role biomass could play, whether the United States has the land resources and whether such a plan would be economically viable." The report found that nearly half of the 2,263 million acres of land in the United States has the potential for growing 1.3 billion dry tons of biomass. Under the most optimistic scenario only 1.0 million acres would be required to produce 80 billion gallons of ethanol. The report also stated that biomass has recently surpassed hydropower as the single largest renewable energy resource in the United States, producing nearly 3% of the total energy consumption using 190 million dry tons of biomass.
REA went on to say that the current production of ethanol, 3.4 billion gallons a year, could be increased to 80 billion gallons a year by 2030. Biomass would supply 5% of the nations power, 20% of its transportation fuels and 25% of its chemicals. This goal is equivalent to 30% of current petroleum consumption. This would also result in a 10% reduction in greenhouse gases.
Some details of the report reveal the following -- From agricultural lands alone 998 billion tons of biomass could be harvested while still meeting food, feed and export demands. The agriculture production assumed significant improvements in yields of food and feed products, as currently assumed by USDA, to free enough land to produce the feedstock for biofuel production. No additional acres of land are required to meet these figures. The use of more waste material, increased yields from cropland, changes in uses of cropland and growing of perennial crops would be the largest factors in obtaining the biomass. Existing forest lands could produce 368 million tons annually through higher utilization of existing biomass.
Agricultural land totals 455 million acres, 349 million of which are used to grow crops, 39 million acres of idle cropland and 67 million acres are used for pasture. A total of 448 million acres were considered in the study (Some cropland was not included because the quantity of land varies because of weather conditions at the time of planting, crop prices, government programs and continued urbanization). Grain and oil seeds are the primary sources used today with food, feed residues and tertiary post-consumer residues used to produce a modest amount of electricity. The following items were included in some scenarios as means of producing additional biomass. A range of figures indicates the change values from the moderate yield to the high yield model.
- Increased crop yields follow historical trends over the past 50 years. Currently the use of more biotech hybrids is making a large contribution to this trend
- Continued historical trends in changes in land allocated to different crops.
- No-till cultivation was assumed more widely used. No-till cultivation increases the amount of residue per acre. It is also very environmentally friendly, reduces erosion and maintains soil structure and nutrients.
- Improvements in harvesting technology are estimated to increase the amount of residue that could be removed from less than 40% to as high as 75%. This combined with no-till cultivation causes a significant increase in yield.
- Allocation of cropland to perennial crops increases the yield per acre to 4.7-7.4 tones per acre, compared to 4.1 to 4.9 tons per acre for corn.
Three scenarios were developed as described below, with the quantity of biomass available given for each scenario.
- Using current agriculture practices the available biomass is 148 million tons annually. Only one-fifth of this biomass is currently used. The largest single untapped source is 75 million dry tons of corn stover.
- Increased crop yields as currently assumed by USDA and changes in tillage practices and harvesting, could increase the amount of available biomass to 420 to 597 million tons.
- Land use changes, changes in tillage practices and harvesting, and the addition of perennial crops, such as switch grass and hybrid poplars, results in the availability of from 581 to 998 million dry tons of biomass.
Total forest land in the U.S. is approximately 749 million acres. The potential amount of forest-derived biomass that can be produced from this land is estimated to be approximately 368 million dry tons annually. None of this land would be used exclusively for production of biomass to produce biofuels, agricultural lands would be used to produce woody biomass specifically grown for biofuel production. Secondary biomass for fuel production would come from:
- Logging residues, the biomass removed from the forest inventory as a direct result of conventional forest harvesting operations.
- Fuel treatment thinning, the removal of excess woody material, i.e. undergrowth, which would reduce the potential for forest fires and improve forest health and productivity.
- Forest products industry wastes: bark, chunks, slabs, shavings and sawdust.
- Urban wood residues come from municipal solid waste (MSW), construction and demolition.
- Forest growth, to meet increasing demands for forest products will increase the availability of forest residues for bioenergy.
While the quantity of biofuel that could be produced is very encouraging, the time estimated to reach this goal is disappointing. Technological developments that are required for the increased production takes time and construction of the required infrastructure takes additional time. The two major technological barriers are 1) implementation of enzyme technology which would permit the use of cellulosic feed stocks and 2) development of methods for harvesting the varied new feedstocks. They did not consider producing ethanol from algae, which could produce all of our liquid fuel consumption on a small portion of our arid land. Very little money is being allocated for biomass R & D. Increased funding might reduce this time frame by 5 to 10 years. Realization by our administration and legislators of the imminent reduction of the supply of crude oil and the resulting need for a crash program to implement these changes is of utmost importance.