Plant Power: A Special Report on Biofuels
Algae are among the most promising new fuel crops because they are packed with lipids-plant oils-that can be converted to biodiesel. Algae grow rapidly and can be farmed on non-arable land with salt water or wastewater. They thrive in sunlight, inhale carbon dioxide and need little fertilizer. “Algae are the kings of high-energy molecules,” says cell biologist Stephen Mayfield, a long-time algae researcher. “It will grow in incredibly crappy water, on incredibly crappy land,” and in some cases can help clean them up.
Mayfield is co-director of the San Diego Center for Algae Biotechnology, a partnership between biotechnology companies and leading San Diego universities and research institutions–San Diego State University, the University of California-San Diego, the Scripps Institute of Oceanography, and the Scripps Research Institute. Created in 2009, the center is operating the Imperial Valley farm to learn how to grow algae at a commercial scale. The goal is to help turn San Diego into the Houston of green crude. Call it Slime-icon Valley.
Flasks of neon-hued algae fill Mayfield’s laboratory at the Scripps Research Institute, where he and colleagues are growing multiple algae species to identify the most promising strains. Some algae species produce a whopping 50 tons of biomass (plant matter) per acre annually. That’s three to four times the amount produced by land plants. Algae also generate up to 50 times the amount of oil per acre compared to vegetable oil crops such as soybeans and canola.
Some of the species known to the public as blue-green algae are in fact cyanobacteria. These tiny microorganisms (spirulina is the best-known species) are believed to be the ancient relatives of all plants, and some theorize that cyanobacteria that decayed in the oceans over the millennia produced much of today’s petroleum.
Like algae, cyanobacteria are photosynthetic. About 30 percent of the oxygen in our atmosphere comes from these organisms, which exist throughout the oceans and in unforgiving habitats from desert crusts to Arctic tundra. “We owe it all to cyanobacteria. They put the oxygen in our atmosphere,” says University of California- San Diego molecular biologist Susan Golden, who is raising these oil-rich microorganisms as part of the San Diego research initiative.
The inclusion of biofuels in our fuel mix is appropriate when considering history. Before the advent of Big Oil, some of the great inventors and entrepreneurs of transportation envisioned a future powered by biofuels. Henry Ford built the first Model Ts in 1908 to run on ethanol. Inventor Rudolf Diesel envisioned his engine running on plant oil.
Entrepreneurs envision a day when large farms with row after row of shallow ponds will mass-produce algae and cyanobacteria. Local refineries would squeeze out the oil and make animal feed or other products from the leftover biomass, which is high in protein. As with all agriculture, algae farming at a large scale would have consequences for habitat and wildlife, but supporters say the footprint in terms of land use and natural resources would be far smaller than that of other fuel crops. The Southwest is a hotspot for algae startups due to year-round sun and vast amounts of arid land unsuitable for other types of agriculture. Sapphire, the largest algae biofuels venture in the United States, is building a large farm in New Mexico. Major oil companies including Chevron, Shell and BP are funding algae research, and the Air Force is eyeing algae as a source of jet fuel.
The biggest hurdle to commercializing algae biofuel is learning how to grow it affordably in massive quantities. Algae biodiesel would cost an estimated $20 to $30 per gallon today. “As we learn to grow it in large quantities, that price will come way down,” says Mayfield, who optimistically hopes for $100 per-barrel algae fuel in three years. “We’ve never grown algae at a large scale,” he says. “We need to take the tools we’ve developed in American agriculture and apply those to algae. We need good basic research on algae domestication. We are developing this from scratch.”
The work is frenzied. “Everyone wants this technology to be working yesterday,” Golden says. “We are trying to do in a few years what it took plant and microbial scientists decades to accomplish. Everyone is scrambling. But there is so much excitement about the potential.”
Climate change and concerns about the nation’s reliance on foreign oil have kicked off a race to produce biofuels to power our vehicles. Limited amounts of biodiesel and ethanol have been available at the pump for years, but both currently come from food crops. Ethanol is made from corn starch, sugar cane and sugar beets. Most biodiesel comes from soybeans and palm oil. Making fuel from these food crops is viewed as unsustainable due to population growth and rising demand for food worldwide. Such fuels also have a climate impact: Palm oil is grown in tropical countries on land that was once rainforest. The GHG (greenhouse gas) emissions from clearing land for oil palm plantations are responsible for making Indonesia the third highest GHG emitting nation in the world despite its low level of industrialization.
Now, researchers are working to produce so-called advanced biofuels from algae and other inedible crops. These “feedstocks” would be especially useful for meeting the fuel needs of the developing world, but the massive amounts of fuel consumed by wealthy nations will likely never be replaced with biofuels–unless major conservation initiatives are implemented, experts say. There simply is not enough land.
For that reason, crop residues and wastes are the most promising materials. Cellulosic ethanol is the chief contender to replace corn ethanol. Cellulosic ethanol is made from fibrous plant matter. Any plant matter will do–grasses, corn stalks, wheat chaff, yard waste, wood chips and even trash. “The tantalizing part is there are lots of ways to make it,” says Jim McMillan, group manager for biochemical refining at the National Renewable Energy Laboratory. “For researchers and engineers, it’s really hot.”
Land-grant universities across the country are growing and testing crops as part of the federal Sun Grant Initiative, a partnership with national research labs to identify regional sources of cellulosic ethanol. The University of Hawaii is investigating the potential of sugarcane stalks, Purdue is growing miscanthus, South Dakota State switchgrass, Kansas State is experimenting with sorghum, Nebraska and Minnesota with corn stover (corn stalks), and Texas A&M with wheat and cereal grain residues.
The federal government is pumping money into advanced biofuels research in anticipation of new fuel standards that will require 36 billion gallons of plant fuels to be produced in future years. The Obama administration included $786 million for biofuels research in the 2009 federal stimulus package. That’s a massive funding increase and comes atop the $217 million appropriated to the Department of Energy in 2009. The Department of Agriculture is also increasing funding.While biofuels have the potential to lower greenhouse gas emissions, they will not do so if they cause more habitat to be converted to crops–often called indirect land use change. Growing fuel crops can also lead to land being removed from food, feed and fiber production at a time when global need is rising. A 2008 study by the Carnegie Institution and the Global Climate and Energy Project at Stanford concluded that using all of the abandoned agricultural lands worldwide–roughly 1.1 billion acres of farmlands that are degraded or have gone fallow–to grow biofuels would supply only a fraction of the world’s current demand.
Critics say it would be wiser to spend the large sums of money now being devoted to biofuels to instead improve energy efficiency and conservation. American and European Union scientists have cautioned against a rush to biofuels, warning that it could increase pressure on land, water and biodiversity. Corn ethanol provides a cautionary tale.
Corn farming is water- and energy-intensive. Corn also requires lots of fertilizer, which is made with fossil fuels. These factors give corn ethanol a high carbon footprint. When the Environmental Protection Agency did a life-cycle analysis of corn ethanol, factoring in greenhouse gas emissions from farming techniques, deforestation and the conversion of natural habitat to farms, the EPA found that corn ethanol actually emits more greenhouse gasses over 30 years than gasoline. Corn ethanol has also been blamed for causing corn prices to rise, and causing food shortages in parts of the globe. Due to the drawbacks of corn ethanol, Congress has capped the amount that can be produced in future years.
The disadvantages associated with corn ethanol are spurring efforts by university researchers to improve this major American crop. “There is a faction out there that thinks nothing good can come from corn,” says Bruce Dale, a Michigan State professor affiliated with the Great Lakes Bioenergy Research Center. “I think corn can be improved. It’s not a perfect crop, but it’s also not going away,”
The Great Lakes center is studying methods to grow corn sustainably. Low-till farming greatly reduces the greenhouse gas emissions from corn farms. “Turn the soil over as little as possible,” Dale says. Plowing up the soil releases carbon stored underground. In low-til farming, seeds are pushed or drilled into the soil, keeping the surface crust intact. This helps the soil retain nutrients and moisture, reducing fertilizer use and irrigation-both energy intensive. The Great Lakes center is also manipulating the genes of corn and other crops to increase the amount of oil in the stems and leaves. The oil could be extracted for biodiesel and the remaining plant material used to create cellulosic ethanol.
Corn and sugar ethanol have a bad rap, but agro-business is working hard to lower the carbon footprint of these crops. “The corn and sugarcane industries are not standing still,” says McMillan of the National Renewable Energy Laboratory. “The life-cycle benefits of corn and sugar cane are getting better.”
Steven Hutcheson, a microbiology professor at the University of Maryland, is leading the charge to create biofuel from another abundant resource: garbage. About half of the paper used in the United States ends up in landfills, where it decomposes and emits greenhouse gasses. Instead, it could be turned into cellulosic ethanol. “There is great appeal in taking waste and turning it into fuel,” says Hutcheson.
Cellulosic ethanol is produced by breaking down cellulose into its constituent sugars, which are then fermented. The pre-treatment phase of breaking down cellulose is expensive–by some accounts 65 percent of the cost of producing cellulosic ethanol.
Hutcheson says he can greatly reduce the cost of pre-treatment thanks to a rare bacterium discovered in the Chesapeake Bay. The bacterium has the amazing ability to break down a wide variety of plant matter, he says. “This is one of the rare bacteria that can take complex biomass, any raw form, and degrade it to its constituent sugars. It’s very unusual to find a single bacterium that does that. We can have it eat corn leaves or wood pulp.” Hutcheson has named the bacterium Saccarophagus degradans, “sugar eater” in Latin.
Later this year, Huthcheson and the company he founded, Zymetis, plan to erect a facility outside a Maryland paper factory. Using the sugar eater bacterium, the facility will make cellulosic ethanol from non-recyclable paper waste destined for landfills. Eventually, the process could be scaled up to work with a range of businesses that generate paper waste-particularly offices and paper mills. Hutcheson envisions a day when the waste stream is mined for organic materials to make cellulosic ethanol.
A Southern California company is already doing this. BlueFire is building a biorefinery to make cellulosic ethanol and other industrial products from urban waste. Biorefineries are analogous to petroleum refineries, where crude oil is processed into gasoline, diesel, jet fuel and a host of specialty fuels and industrial products. Instead of oil, biorefineries would use biomass. The National Renewable Energy Laboratory is working with a number of companies, including BlueFire, to build demonstration biorefineries in various parts of the country.
Switchgrass may be the best-known source of cellulosic ethanol. Former President Bush mentioned it in a State of the Union address, and the National Renewable Energy Lab has identified switchgrass as a leading biofuels crop. University of California-Davis agronomist Dan Putnam was skeptical about switchgrass until he began growing it. “Now I’ve come to the conclusion it is a good choice.”
The switchgrass growing in Putnam’s test plot in Davis was already chest-high in late May. University of California agronomists are growing switchgrass in four locations ranging from Southern California to the Oregon border to test which varieties grow best in various climates. “Every region of the country will have its own biofuel source. There won’t be one crop,” Putnam says.
Planted in 2007, Putnam’s switchgrass is a lawnmower’s nightmare. “We’re probably reporting some of the highest yields in the U.S.,” he says. In 2008, his switchgrass grew at a rate of 19 tons per acre. “This year we will likely be higher than that.”
Putnam is now studying the water requirements of switchgrass. “We call it regulated deficit irrigation: How little water can you use and still get a good yield?” To be grown in abundance, biofuels will need water-an increasingly scarce resource in many regions. Growing biofuels will also increase competition for arable land. “The demand for food is going to increase and water is going to get scarcer,” Putnam says. “We need to figure out how to integrate food and fuel crops.”
Plant fuels can lower carbon emissions from vehicles because plants inhale CO2. This has stimulated interest in biofuels by one of the environmental community’s biggest foes-the coal fired power industry. At the University of Kentucky, researchers are devising ways to grow algae with power plant CO2 emissions.
“Technically it’s not sequestration, which is storing carbon. This is CO2 utilization and management,” says Rodney Andrews, director of the University of Kentucky’s Center for Applied Energy Research. Later this year, Andrews hopes to begin growing algae with CO2 from a small coal power plant. About half of the electricity nationwide comes from coal plants, which face impending carbon regulations.
But there are big technical and logistical challenges to affordably growing algae with power plant emissions: One medium-sized power plant would require a 5,000-acre pond to use up all its CO2. The greenhouse gas would have to pumped or somehow dissolved and transported to the algae, requiring costly infrastructure.
All of the Above:
Replacing petroleum is a gargantuan task. Americans annually consume 140 billion gallons of gasoline and 60 billion gallons of diesel. Biofuels production is paltry by comparison. In 2008, the nation produced 13 billion gallons of corn ethanol and 2.6 billion gallons of biodiesel. To date, only token amounts of cellulosic ethanol and algae biodiesel, which has powered several commercial airline flights, have been produced.
But that’s about to change. “We’re a couple years away from seeing millions of gallons of cellulosic ethanol coming online, says McMillan. “Once the tech is proven, we can propagate it quickly.”
Biofuels are a path to sustainability, but they must be paired with conservation, McMillan says. “If we continue consuming 140 billion gallons of gasoline per year, then we paint ourselves into a corner.” All of the various biofuels have pros and cons, he adds: “For the foreseeable future, we need all of the above.”
As research continues, caution is warranted. National Wildlife Federation has helped to establish the Roundtable on Sustainable Biofuels (RSB), which is an international organization dedicated to setting voluntary standards that can be used by large retailers and consumers to identify the “better biofuels” in the marketplace. Consumers can encourage the production of “better biofuels,” which are those produced with less environmental and social harm, by specifically asking producers to seek certification under the RSB rules. A wiki on bioenergy will include the draft standards, to be completed later this year.