Biofuels

Jatropha

A newly engineered variety takes off in aviation biofuel

What is it?

Jatropha is a hardy tropical plant whose name is derived from the Greek words for “physician” and “nutrition.” Its leaves and seed pods are poisonous, but the plant has been used in medicines, mulch, and basket-weaving, made into organic fertilizer and rodent repellent, and as a cover crop to shelter other crops and prevent erosion. And inside the pods are beans that can be crushed and made into oil for soap, cosmetics, lamps, and biofuels.

What is it of interest?

Almost a decade ago, the drought-tolerant, inedible bush that grows on marginal land in the tropics was hailed as the next big thing in biofuels. Investors poured hundreds of millions of dollars into jatropha plantations only to discover that the plants yielded far too few oil-rich seeds to be commercially viable, especially as petroleum prices fell sharply in the wake of the Great Recession. Recently a San Diego startup called SGB, however, has identified potentially high-yielding jatropha strains at the molecular level in the laboratory, a process that allowed the company to domesticate jatropha in a matter of years rather than decades.

Where does it grow?

Jatropha is most commonly found in Indonesia, the Philippines, Cambodia, India, Mexico, Central America, and South America.

Why does it matter?

Jatropha been used successfully to make diesel in places like the Galapagos Islands, where the island Floreana has replaced fossil fuels with cold-pressed jatropha oil. Tourist busses in some parts of India are already running on jatropha oil. And a bioengineered variety of jatropha has boosted its jatropha seed yields by 900 percent.

What’s next?

Besides producing local jatropha biodiesel, regions in some countries are planting jatropha seeds for aviation biofuel.  One biofuel company has deals in place to plant jatropha on 250,000 acres in Brazil, India and other countries that would produce an estimated 70 million gallons of biofuel a year. Jatropha can’t supply all the fuel needed for aviation, since, as one commentator has noted, the 1.6 billion gallons of jet fuel needed each year would require 285 million acres of jatropha to satisfy our annual demand -- a land area about the size of four large U.S. states combined -- but it could make a dent in their fossil fuel use.

Who is working on it?

Besides Brazil, India, and the United States, companies are investing in jatropha in countries ranging from the Bahamas and Costa Rica to Ethiopia, Ghana, Guatemala, Jamaica, Kenya, Mexico, Sudan, and Zimbabwe.

From Bio…To Fuel, II

A bacterium that can grow just about anywhere

What is it?

Clostridium is a genus of about 100 free-living bacteria and disease-causing agents (pathogens) that are capable of producing endospores. Individual cells are rod-shaped, from the Greek word Kloster, or spindle. The category includes several bacterium that have played a crucial role in biofuels for decades. 

How does it work?

As early as 1916, scientists used it to produce biobutanol through a process called ABE fermentation – the airless conversion of carbohydrates by Clostridum strains into acetone, butanol, and ethanol.

Why does it matter?

Commercial production of renewable butanol stopped as the petrochemical industry expanded, but over the past decade there’s been renewed interest in biobutanol as a renewable drop-in transport fuel. Scientists are exploring Clostridium acetobutylicum for its remarkable ability to produce a range of metabolites (byproducts) useful to biofuel, as well as its exceptional diversity in the types of biomass it can grow on (everything from dairy and food  waste to straw).

Where can I read more?

Check out the EBI paper "Engineering Clostridium Acetobutylicum for Production of Kerosene and Diesel Blendstock Precursors," by S. Bormann, Z. C. Baer, S. Sreekumar, J. M. Kuchenreuther, F. Dean Toste, H. W. Blanch, and D. S. Clark, in Metabolic Engineering, 25: 124-130. doi: 10.1016/j.ymben.2014.07.003, July 22, 2014.

 

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