Can Biofuels from Non-food Sources End the Food Versus Fuel Debate?

By Brian Turano, Richard Ogoshi, and Goro Uehara
College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa

Ethanol from sugar and starch, and biodiesel from cooking oil are luxuries the world could ill afford. Earlier this year, food prices skyrocketed internationally in response to the increased demand for corn grain and vegetable oil to make biofuels, resulting in food riots in developing countries and igniting the fuel versus fuel debate. A World Bank report concluded that conversion of food into biofuels raised food prices about 75 percent in developing countries. Clearly, the honeymoon for food-based biofuels has ended.

What does this mean of us in Hawaii? With wind, solar, geothermal, wave and ocean thermal energy resources yet to be fully tapped, do we need to consider biofuels to meet the challenges of a clean, renewable energy future? Biofuels are critical to our energy needs because unlike other renewable energy resources that generate electrical power, ethanol and biodiesel can substitute for the most common transportation fuels, gasoline and diesel. We may be driving battery-powered vehicles in the future, but we will be pumping liquid fuel into cars for the foreseeable future. Hawaii’s energy future looks brighter as we learn more about the promise of producing cellulosic ethanol and biodiesel from high yielding, non-food oil crops.

Our ancestors converted grape sugar and starch from grains into alcohol with the aid of microorganisms for millennia. This “first generation” technology is used today by Brazilians to produce ethanol from sugarcane and by U.S. biorefineries to produce ethanol from corn starch. We will continue to use first generation technology to produce alcohol for human consumption, but the days of using sugar and starch as feedstock for conversion into ethanol as substitute for gasoline are over. A second generation technology is now being developed to convert more plentiful and less expensive cellulose and other non-food biomass into biofuels.

Cellulose, like starch, is a giant molecule made up of long chains of sugar molecules and is the major component of plant leaves and stalks. While humans are unable to digest cellulose for food, cows and other ruminants produce enzymes that can break down cellulose into sugars. Termites that bore holes into wood and damage our homes also produce enzymes that can break down cellulose into sugars. Some second generation biofuel technologies utilize the biochemical processes used by ruminants and termites to convert cellulosic materials into fermentable sugars.

When will this second generation technology be ready? Last year the U.S. Department of Energy (DOE) announced that it will invest $385 million in six large private industry projects to accelerate the commercialization of cellulosic ethanol production. The DOE’s short term goal is to produce ethanol at a cost of $1.33 per gallon by 2012, and its mid-term goal is to have sustainable biofuel production by 2017. In line with these national goals, Hawaii’s goal is to have 70 percent of our energy needs supplied by renewable sources by 2028.

What is the likelihood that this goal can be attained in Hawaii? The state currently consumes approximately 475 million gallons of gasoline annually. Given the lower energy content of ethanol compared to gasoline, the state will roughly need the same volume of ethanol it now consumes as gasoline to meet the 70% goal.

Where will this ethanol come from? We know that with current second generation biofuel technology, it is possible to extract 70 gallons of ethanol from each ton of biomass. This means the State will need to produce about 7 million tons of biomass each year as feedstock for conversion into ethanol. We also know from our field trials that an acre of land in Hawaii is capable of annually producing 10 to 40 tons of biomass depending on crop type, watering, chemical inputs and land quality. If we assume an average biomass yield of 20 tons per acre per year, 350,000 acres would be needed for ethanol production. Hawaii has about 1.3 million acres of zoned agricultural lands and forests. 675,000 acres are designated as prime agricultural lands of importance to the State of Hawaii (AGLISH) of which less than 200,000 acres are under cultivation. Although there appears to be enough land for bioenergy crops it is important to remember that for biofuel production to be financially feasible large tracts of land must be in close proximity to the ethanol biorefinery site. Transportation of raw biomass over long distances would be cost prohibitive. Much of the land formerly under sugar and pineapple production is rapidly being converted to non-agricultural uses or under lease for diversified crop production with little chance of being used for ethanol production.

Where will we find the land needed to produce feedstock for our transportation fuels? Should the State use its prime agricultural lands to grow energy crops? The food versus fuel debate is not only about using food as feedstock for producing ethanol, but extends into the concern about using agricultural land for growing energy crops instead of food crops. Now, more than ever, there is a demand that our prime agricultural lands be reserved for food and other high value crops. It turns out that our prime agricultural lands, formerly planted to sugarcane and pineapple, occur in warm, low elevations sites where rainfall is adequate or water for irrigation is plentiful. Such lands make up a small fraction of the 1.3 million acres of agricultural land in the state.

There are, however, extensive areas of underutilized lands, especially on Maui and the Big Island where the climate is too cold or too dry for sugarcane or pineapple that have high potential for producing biomass. On the windward side of the Big Island, Maui and other islands, at elevations above 1500 feet, where rainfall is high but temperatures are too low for heat-loving crops such as sugarcane and pineapple, extensive areas of underutilized land, much of it infested with non-native invasive species need to be evaluated for energy crop production. The area of this high elevation, high rainfall zone far exceeds the area of land formerly planted in pineapple and sugarcane, and warrants evaluation for its potential for producing, cold tolerant energy crops in an environmentally sustainable manner. Much of this land is currently used for pastures and a small portion for vegetable production as in Kula on Maui and Kamuela on the Big Island.

A second, equally extensive underutilized zone in the State occurs in the rain shadow of the high mountains. This area is too dry for food crop production and lacks readily available water for irrigation. This land is mostly under pasture, but has potential for growing high yielding grasses for conversion into biofuels. This zone receives 25 to 40 inches of rain mostly in the winter months. Our studies show that about two-thirds of the rain that falls in this area is lost as runoff leaving only a third for plant use and ground water recharge. This zone can be transformed into a major energy crop producing area by making better use of the rain that falls by application of proven rain harvesting technology. This practice reduces runoff from two-thirds to one-third of rainfall resulting in more water for crops, recharge of groundwater, less soil erosion, more stable stream flow and less downstream flooding during heavy storms in the rainy season. By increasing crop yield, water harvesting also increases organic matter content of land by increasing below ground biomass. About 20 to 40 percent of a plant’s biomass is below
ground and this biomass is transformed into soil-enriching humus so long as the land is not tilled. Tilling or plowing land can be avoided by growing high yielding perennial grasses that can be repeatedly harvested without need for replanting. By growing high biomass yielding, non-food crops on underutilized lands, the State will be able to deal simultaneously with four problems facing it today, namely, climate change, energy security, food security and water security.

Increasing crop yields through rain harvesting will slow climate change by sequestering carbon as soil organic matter. Should carbon trading become a reality, the carbon stored in soils can be traded for CO2 emitted by polluting industries to generate new income for landowners. In addition, the biomass produced on improved, underutilized land enables the state to lessen its dependence on imported fossil fuel and permit prime agricultural lands to remain in traditional food crop production. Lastly, rain water that is lost as runoff can be harvested for producing feedstock for conversion into biofuels.

Rain harvesting will also increase farmers’ profitability. Farmers now pay approximately 40 cents per 1000 gallons of water for irrigation. An acre inch of water contains just over 27,000 gallons of water and if purchased will cost a farmer just over $10. In areas receiving 40 inches of rainfall each year, harvesting 12 inches of rainwater now lost as runoff enables landowners to annually capture $120 worth of water from each acre of land. Underutilized biomass and water on underutilized land may in the years ahead become the basic resources for a new biofuel industry.

Hawaii would be fortunate indeed if it could meet its clean energy goals by utilizing 350,000 acres of land. But given population growth and pressures to convert more agricultural land for urban use, what hope is there that a sustainable supply of biofuel can be produced into the distant future? The 350,000 acre area required to keep the State supplied with biofuel is based on biomass yields of 20 tons per acre and a biomass to biofuel conversion rate of 70 gallons of ethanol per ton of biomass. This area can be substantially reduced if thermochemical technology now being tested proves capable of converting each ton of biomass into 110 gallons of ethanol. This technology converts more biomass into biofuel because unlike biochemical processes that can only convert cellulose and other sugar polymers to ethanol, thermochemical methods also converts lignin which makes up a significant part of biomass into hydrogen and carbon monoxide which in turn can be synthesized into a variety of biofuels for use in gasoline, jet, and diesel engines. An even more promising way to reduce land area required to produce biomass is to increase biomass yields. By breeding and selecting higher yielding varieties, it should be possible to double current biomass yields just as crop yields of our major grain crops have been increased in the past. Thus, by a combination of improvements in conversion technology and producing higher yielding varieties, the State should be able to meet its biofuel production goals even in the face of population growth and land competition for urbanization.

In the final analysis, producing clean renewable transportation fuels on underutilized lands can succeed provided the transformed agroecosystem acquires the four properties of sustainability. These properties are:
1. High productivity measured in terms of crop yield and farm income.
2. High stability measure in terms of consistency in yield and income over time.
3. High resiliency measured in terms of a capacity to recover quickly from stresses and perturbations imposed on the agroecosystem.
4. High equitability measured in terms of fair sharing of benefits derived from the
agroecosystem.

To transform the State’s underutilized lands into productive, stable, resilient and equitable agroecosystems, a new generation of workers will need to be educated and trained to apply second and third generation biofuel technology to lessen our dependence on imported foreign oil for transportation needs. Hawaii has the land resources and can build the human capacity to meet this challenge. We now need the determination and will to begin the transformational process to move the State into a new era of food, energy and water security for all.