environment/sustainablebiofuels/sustainability/
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Types of Sustainable Biofuels

Many people are familiar with "first-generation" biofuels such as ethanol and biodiesel, which are primarily derived from corn and soybeans at present. Yet corn and soybeans are staple food crops and require large amounts of land and resources. This makes them unsustainable sources for biofuel. It's unlikely that the demand for sustainable aviation fuels will be met by a single biofuel plant source, which makes a portfolio of solutions the best approach.

Within this portfolio, examples of promising plant sources that meet the criteria for sustainability include:

• ALGAE: Algae are simple, photosynthetic plants lacking leaves and roots. Independent studies have demonstrated that algae are capable of producing 30 times more oil per acre than the current crops now utilized for the production of biofuels. Algae biofuel contains no sulfur, is non-toxic and highly biodegradable.
• CAMELINA: It known as a false flax and is a member of the mustard family. It is tolerant of low rainfall and can grow in areas unsuitable for food crops. It is cold tolerant and its oil is more resistant to cold temperatures than other oils. Crop yields are double those of soy beans and the meal left over after producing biofuel oil is a good candidate for livestock feed.
• HALOPHYTES: Halophytes are salt marsh grasses and other species growing in saline habitats. They don't compete with food because they grow in environments unsuitable for traditional crops. Early testing on these plants shows that they have high lipid,or plant-oil,content and can deliver very high yields per unit of land.
• JATROPHA: Jatropha is a widely distributed non-edible plant that grows well on non-arable land and features a high-oil-yield nut. It shows strong potential to help fight desertification in arid regions, and thereby reduce climate change impacts and add economic value to developing-world economies if grown sustainably.
• NON-FOOD CELLULOSE: Non-food cellulose is a broad term that refers to plant matter which does not contribute to human food supplies either directly or indirectly through animal feed. A wide a range of sources such as seaweeds, forestry waste, or drought-tolerant perennial grasses all show promise for conversion into biofuels, while reducing competition between food and fuel.

The promise of algae

Algae are particularly compelling sustainable plant sources for biofuels. Supplying the entire worldwide commercial airline fleet with 100-percent-sustainable biofuel from soybeans would require enough square kilometers to create a landmass larger than all of Europe. Comparatively, doing the same using 100-percent-sustainable biofuel from algae would require just 35,000 square kilometers, a landmass roughly the size of Belgium. Algae will also grow in places where we can't currently grow crops, such as in brackish water, and they have the ability to absorb massive quantities of CO2. Recognizing the tremendous potential and benefits of algae, over 400 leading experts gathered for the world's first Algae Biomass Summit in November 2007. Attendees formed the Algal Biomass Organization (ABO) to collectively push for algae-based energy solutions. ABO was officially chartered in May 2008.

ABO committee members include:

Bill Glover and Darrin Morgan, The Boeing Company (committee co-chairs)
Thomas Byrne, Byrne & Company Limited (committee secretary)
Mark Allen, A2BE Carbon Capture
Dr. John Benemann, Benemann Associates
Dr. Keith Cooksey, Montana State University
Tyler Krutzfeldt, Mont Vista Capital
Dr. Greg Mitchell, Scripps Institution of Oceanography
Dr. Philip Pienkos, National Renewable Energy Laboratory