High Hopes for Growing a Green Fuel in Arid East Africa
By Jon Luoma
Note: Yale School of the Environment (YSE) was formerly known as the Yale School of Forestry & Environmental Studies (F&ES). News articles and events posted prior to July 1, 2020 refer to the School's name at that time.
<p class="p1"> The arid landscape of the Tigray Region in Ethiopia where API is growing oil crops for biodiesel.</p>
Since graduating from Yale in May 2010 with a degree in environmental engineering, Noah McColl has been spending a great deal of time thinking about what to do with leftovers. Not leftovers from yesterday’s meal, but rather what some might have traditionally seen as industrial wastes from the process of making fuel out of green plants. McColl would prefer to see these not as wastes at all, but as resources that can become “co-products.”
Since shortly after graduating, McColl has been working as a liaison between Yale’s Center for Green Chemistry and Green Engineering and an ambitious venture called the African Power Initiative (API) based in Kampala, Uganda. API, which also has begun operations in nearby Ethiopia, aims to pay farmers in the region to grow on otherwise marginal lands an array of hardy plants that yield oils that can be transformed into a chemical cousin of fossil-based diesel fuel, or biodiesel.
In the United States, existing federal mandates requiring biofuels to be mixed with gasoline have often faced intense criticism, not least because the most abundantly produced biofuel in the United States—ethanol—is made primarily from corn. That’s been a boon to corn farmers, who’ve been enjoying soaring prices, but according to a report in Technology Review the mandates are “a major reason why food prices worldwide have reached record levels in the past several months.”
Thousands of miles from the cornfields of North America, API is approaching biofuel differently, aiming specifically not to compete with food crops. A private company, API has set out to prove that it can make biodiesel economically competitive with expensive, imported fossil fuels in east Africa by taking advantage of what happens to be locally abundant: sunshine, inexpensive marginal land and farmers eager to find new ways to boost meager family incomes.
API has already begun to work with farmers to plant oil-yielding crops like castor, candlenut and jatropha. All of the targeted crops will grow on marginal soils under, at least, semi-arid conditions. Castor beans, for instance, will grow in sandy soils, jatropha in gravelly as well as sandy soils, and candlenut in a wide range of stony, clay or sandy locations. Castor can flower and set fruit with as little as 20 inches of annual rainfall; the other two crops need just a bit more water to be productive. As a point of reference, that’s about the yearly precipitation in semi-arid west Texas.
Jatropha curcas seed
The notion of using plant oils as a source of fuel is hardly a new idea, nor is even the idea of growing the fuels specifically in Africa. At the 1900 World’s Fair, the French government demonstrated a novelty: a diesel engine that ran on peanut oil, suggesting that vegetable oil, produced locally, might be ideal for use as a fuel in what were then France’s African colonies.
Today’s version of biodiesel uses a process developed in the 1930s called transesterification that is designed to help the fuel more closely match the properties of the more viscous, petroleum-based fuels that wound up prevailing in modern diesel engines. After energy-rich seeds are milled to release their oil, the vegetable oils are exposed to heat, pressure, alcohol (methanol in API’s process) and an alkaline catalyst, yielding small-molecule fatty acid methyl esters, or informally biodiesel, a fuel pure enough that it tends to burn cleaner than its fossil fuel-based cousin.
Substituting biofuels for fossil fuels can also reduce greenhouse gases emissions, since the combustion of biofuel merely returns to the atmosphere the carbon recently removed via photosynthesis.
The biodiesel can be directly substituted for conventional diesel or blended with it. API has already installed its first biodiesel plant in Uganda and is planning to ramp up production from a few hundred liters a day in late 2011 to a projected 2,000 liters in the first quarter of 2012, moving to a full design capacity of 60,000 liters as more oily feedstock becomes available.
A newer, smaller pilot plant in Ethiopia is slated to begin limited operations this year. In both countries, the company should have a ready-made local market for the fuel, since both now require a blend of at least 20 percent biofuel in diesel. API has also reported that it has signed an agreement to supply its fuel to Tamoil, a major fuel wholesaler in east Africa.
Biodiesel isn’t all that the process yields, and that’s where Yale and green chemistry and green engineering come in. As capacity ramps up, API will eventually need to mill tons of seeds daily. It projects that a liter of diesel it produces will also yield as much as a kilogram of discarded seed husks, along with other byproducts of the transesterification process, such as glycerin.
The Yale collaboration with API actually began in the summer of 2008 with the arrival of McColl’s predecessor, Andrew (“Drew”) Klein. Then a year away from completing an undergraduate degree in chemistry and environmental engineering, Klein had trained with Yale’s Paul Anastas, the “father of green chemistry” and Teresa and H. John Heinz III Professor in the Practice of Chemistry for the Environment at Yale. That summer after graduating, then for an additional year on a Fulbright fellowship, Klein recruited API’s first team of locally educated scientists and set up the company’s research and development lab with Makerere University in Kampala as an additional partner.
Some of the necessary early work was standard analysis of the first biofuels the company produced, according to Evan Beach, program manager at the Center for Green Chemistry and Green Engineering: “How do you know you have clean biodiesel? What’s the fatty acid content? And so on.”
But the Yale researchers were focused from the beginning on the entire lifecycle of the process. Klein quickly became intrigued by the possibility of finding ways to add economic value to the small mountains of candlenut shells that an API biodiesel pilot plant had begun discarding. It turns out the answer just might be an additional form of biofuels. In 2010 Klein and three Yale faculty researchers published results of experiments demonstrating a novel way to chemically isolate lignin, which is the compound more widely known as the polymer that hardens and binds together cells in the wood. But it’s even more abundant in the tough, extra-hard candlenut shells. The new process effectively extracts liquids from ground-up nut-shell solids that Beach says might one day find practical use as fuel “or as building blocks for even more valuable products like pharmaceuticals.”
Some of the other biomass produced by API might find a humbler use: returned to the land as a soil amendment. “Since the soils are poor, a little extra biomass can help a bit,” said McColl.
Researchers have begun investigating whether the fibrous material can be used as components in building materials ranging from particle board to cement or as fuel briquettes for cook stoves or commercial furnaces.
The byproduct glycerin can be used in such consumer products as soap and cosmetics. Already, says McColl, small-scale artisan soapmakers in Ethiopia have expressed interest in the limited glycerin supply expected to flow from the new pilot plant.
“There are a lot of questions we can help answer about the materials we’re working with,” said McColl. “If the biomass is turned into briquettes for cook stoves, will any emissions be harmful to someone cooking? If this biomass can become a component for the cement industry—and that’s a huge industry here—we need to know what trace elements might be in the biomass and what influence it might have on the quality of the cement.
“We also plan to work on models to get a better idea of how much greenhouse gas can be reduced here by trading off fossil fuels with biodiesel,” he adds. Such modeling could also help show how swapping carbon-neutral biomass for energy-intensive components in products like cement would reduce carbon emissions even more.
McColl says he’s also found himself working with local farmers on “optimal crop management”—tactics that add value to their biodiesel-related cropping operations.
He notes that there’s been hyperbole from some promoters of biofuel crops, like jatropha curcas, the species of the jatropha genus often used as a source for biodiesel. According to some reports, the plant can produce as much as 1,800 liters (475 gallons) of oil on a single hectare (2.47 acres). But that’s under ideal conditions, with abundant water. Since farmers working with API generally won’t be able to irrigate, yields will be less than optimal. So McColl has been helping API and its farmers investigate ways to boost the economic output of their acres. That could mean growing native grasses that can be harvested as livestock forage among the oil-yielding trees and shrubs. Farmers are also being encouraged to try apiculture (bee-keeping) and even epiculture: growing silk worms.
Epiculture, as an income supplement, has worked for farmers elsewhere in Africa. In an effort promoted by the International Fund for Agricultural Development, small farmers in some parts of Kenya have in recent years been finding silk production to be enough of an economic boost that they have been able to pay for, for the first time, schooling for children.
Rather than feeding silkworms on traditional mulberry, as the Kenyans do, API’s farmers are being encouraged to take a more symbiotic approach: to grow a species of caterpillars adapted to feed on the leaves of the same castor plants being used for biodiesel. These silkworms, native to India, produce a type of silk called “eri,” more wooly, with better thermal properties than the conventional fabric.
McColl sums up the whole of the collaboration this way: