As we have seen, some forms of biomass fuel development (e.g., corn-based ethanol) come with significant social and environmental costs. Fortunately, a number of processes under development have the potential to avoid most of those impacts. In addition, many are more efficient from an energy perspective. One of those approaches converts whole plants or agricultural and forestry wastes into ethanol.

With rising demand for biofuels comes the threat of replacing natural ecosystems with bleak monocultures of oil palms or soybeans. However, Brazil, the second largest producer of biodiesel after Germany, has reduced its rate of deforestation mainly through the creation of indigenous reserves and other protected areas, including some set aside for sustainable use (Figure 10.49). The new reserves include over half the Brazilian Amazon Basin, and indigenous people now control approximately 20% of the basin. Strong enforcement and prosecution of violators, including corrupt government officials, followed the legislation creating these forest reserves.

Moreover, Brazil achieved this land protection while increasing its overall agricultural production, including production of biofuels, especially sugarcane and soybeans. In response to pressure from environmental groups, palm oil buyers and their producers in Southeast Asia have formed a coalition called the Roundtable on Sustainable Palm Oil, which seeks to reduce deforestation and environmental harm from palm oil production. In 2013 Wilmar, the world’s biggest palm oil trader, which controls 45% of the market, announced a landmark zero deforestation policy; it will avoid development on areas with high conservation value. Other companies have followed Wilmar’s lead, but it remains to be seen whether they will live up to such voluntary commitments.

Another way to avoid many of the environmental threats stemming from biofuel production is to turn from terrestrial plants to aquatic algae (Figure 10.50). Growing algae, as we noted earlier, will not compete with farm production because they can be grown using brackish water too salty for irrigating crops or for drinking. They also happen to be fabulous environmental remediators. Conveniently, algae need a steady supply of carbon dioxide, along with nutrients such as nitrogen and phosphate. It turns out that agricultural and municipal wastes are rich in nitrogen and phosphorus, which can pollute the water supply by causing harmful algal blooms. Diverting these nutrients to an algae bioreactor, which is a chamber designed to cultivate algae, provides a means to recycle these nutrients and filter the wastewater before it enters the environment. In addition, by diverting the carbon dioxide generated by electrical generating stations into algal cultures, it will be possible to enhance their growth and sequester carbon emissions at the same time.

324

Corn-based ethanol has an energy return on energy investment (EROEI) that barely exceeds a value of 1.0 (Figure 10.51), much lower than gasoline. Although ethanol is a cleaner-burning fuel than gasoline, corn is clearly not going to solve our energy needs. Sugarcane ethanol and soybean biodiesel, by contrast, have EROEIs substantially higher than that of corn ethanol and somewhat higher than gasoline extracted through energy-intensive processes from the Athabasca oil sands. Unfortunately, such fuels are best produced in tropical and subtropical climates, making them poorly suited for most temperate regions. Now look at cellulosic ethanol: It has an EROEI 10 times greater than corn ethanol and approaches that of gasoline from conventional oil. Could cellulosic ethanol be the future? Quite possibly.

In 2013 the cost of cellulosic ethanol was still 30% higher than a liter of corn-based ethanol. However, costs of production are falling rapidly and it should be on a par with corn before 2020. One of the major current costs of cellulosic ethanol is the cost of organic material suitable for production.

Recent reviews identify five promising sources of materials for cellulosic ethanol production (Figure 10.52). Developing these resources could improve environmental conditions in several ways. For example, growing perennial plants such as switchgrass (Panicum virgatum), native to most of the United States and Canada and that grows to 1 to 1.5 meters (3 to 5 feet) in height, has the potential to improve soil fertility by adding to soil carbon. In addition, switchgrass can grow well on a variety of soil types, including shallow soils of marginal fertility and low water content.

325