From Mother Nature Network's John Platt:

Plant waste has long been seen as a possible source of sustainable biofuels, and new research out of Rice University could unlock some of the energy that scientists say lies waiting in organic material.

According to materials provided by Rice, bioengineer Ka-Yiu San and his lab have developed a way to turn plant waste into fatty acid, which can then be further converted into fuel. The key is a genetically modified strain of the E. coli bacteria which they created by combining traits from several other strains. The scientists fed inedible cellulose from sorghum to the bacteria, which converts the sugar-heavy hydrolysate from the plants into fatty acids. These fatty acids could somedaybe converted into synthetic diesel fuel or oil-like lubricants, say the researchers.

San's lab gets some of its funding from the U.S. Department of Agriculture, which recently announced a $25 million effort to develop new bio-based renewable energy sources and related products from switchgrass, sorghum and forestry residue. The E. coli work was funded by the National Science Foundation's Engineering Research Center for Renewable Chemicals. The project was proposed by a Utah-based company called Ceramatec Inc., which hopes to develop a market for fatty acids that could be processed in petroleum refineries.

San reports that his patent-pending fermentation process generates an 80 percent to 90 percent yield of fatty acids from what they called "model sugars" (in other words, this is still a lab-based process). He says his lab, which includes his postdoctoral researchers Xiujun Zhang and Mai Li, have achieved what no other scientists have been able to do to date. Meanwhile, he thinks the process can get even better. "Adding another 1 or 2 percent doesn't seem like much, but when you're talking about making several million tons per year, it's huge."

It will be a while before they're producing millions of tons of fatty acids, though. San say they need to make sure that their E. coli strain is "perfected and robust enough for industry. Strains that behave well in the lab may not do as well in an industrial setting." They hope to have a pilot plant in place to scale up the project in two or three years.

Although this current research has not been published, it builds upon San's previous work, including a paper published in October 2011 in the journal Biotechnology Progress.

Loading Slideshow...
  • Top Renewable Energy Sources

    Renewable energy made up 9 percent of all energy consumed in 2011, according to the <a href="http://www.eia.gov/">U.S. Energy Information Agency</a>, and that number is <a href="http://www.eia.gov/forecasts/aeo/er/pdf/0383er(2013).pdf">predicted to grow throughout the next decade</a>. Here's a breakdown of the top sources of renewable energy in the country, from wind to water and everything in between. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Solar Power - 2 Percent

    Solar power and photovoltaic cells make up the smallest percentage of U.S. renewable energy production, but its future looks fairly promising. Warren Buffett's Berkshire Hathaway <a href="http://www.huffingtonpost.com/2013/01/03/warren-buffett-solar-power_n_2398816.html">invested $2.5 billion in Calif. solar company SunPower</a> earlier this year. Also, unlike other sources of renewables, energy can also be generated by small-scale solar installations (like on the rooftop of a home or business), and<a href="http://www.eia.gov/todayinenergy/detail.cfm?id=8570"> declining costs</a> have made solar much more affordable. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Geothermal - 2 Percent

    Geothermal power captures naturally occurring heat from the earth to turn it into power. The renewable source is geographically dependent, <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=3970">but the Western half of the U.S.</a> has many promising locations for power plants, <a href="http://www.geysers.com/">like The Geysers in Calif.</a>, the largest geothermal power plant in the world. The U.S. is the largest producer of geothermal power on the planet, but growth hasn't kept up with wind or solar development in recent years. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Waste - 5 Percent

    Believe it or not, burned garbage accounts for 5 percent of all renewable energy created in the U.S. each year. More than 29 million tons of municipal solid waste was burned in 2010 to create steam to spin turbines and generate power, <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=7990"> and there are more than 75</a> waste-to-energy plants in the country. Emissions regulations have been in place at waste incineration plants since the 1960s, but the <a href="http://www.epa.gov/ncer/publications/research_results_needs/combustionEmmissionsReport.pdf">EPA warned in a 2006 report that the toxins released</a> during the process could pose a serious environmental risk if not strictly enforced. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Wind - 13 Percent

    The amount of wind power has grown for each of the past three years throughout the U.S. and accounted for the <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=9931">largest growth in capacity</a> of any energy resource in the country last year. Wind turbines now supply more than <a href="http://www.reuters.com/article/2012/10/19/us-utilities-windpower-usa-idUSBRE89I0TX20121019">50,000 megawatts a year,</a> enough to power 13 million homes, according to Reuters. Federal tax credits, which were set to expire at the end of 2012, have made wind farms an attractive form of renewable energy. Congress <a href="http://www.forbes.com/sites/davelevitan/2013/01/02/wind-power-tax-credit-survives-fiscal-cliff-deal/">approved an extension of the credits</a> through the end of 2013. After production, wind turbines are net zero, meaning they require no energy and produce no emissions. The only problematic thing generated in some cases other than clean power has been <a href="http://www.huffingtonpost.com/2011/05/24/wind-power-noise-pollution-maine_n_866182.html">a whole lot of noise</a>. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Biofuel - 21 Percent

    Biofuels, like ethanol, are created from organic matter like corn or soybeans. Gasoline in the U.S. contains 9 percent of the resource by federal mandate under the <a href="http://www.epa.gov/otaq/fuels/renewablefuels/index.htm">Renewable Fuel Standard program,</a> and more than <a href="http://www.huffingtonpost.com/2012/08/10/us-should-change-biofuel-_n_1764735.html">40 percent of the corn crop</a> last year was turned into biofuel. The resource is slightly more unstable than other renewables because it depends on the productivity of farms - <a href="http://www.huffingtonpost.com/2012/08/10/us-should-change-biofuel-_n_1764735.html">drought or other environmental problems</a> can significantly lower yields and increase prices. On average, <a href="http://www.afdc.energy.gov/vehicles/flexible_fuel_emissions.html">ethanol has 20 percent fewer emissions</a> than traditional gasoline but some types, like <a href="http://en.wikipedia.org/wiki/Cellulosic_ethanol">cellulosic ethanol,</a> cut greenhouse gas emissions more than 85 percent, according to the U.S. Department of Energy. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Wood - 22 Percent

    Timber accounts for nearly a quarter of all renewable energy created in the country. <a href="http://news.nationalgeographic.com/news/energy/2012/10/121022-wood-for-heating/">Rising energy costs </a>have led to an upswing in wood burning over the past decade, and nearly <a href="http://www.eia.gov/forecasts/steo/report/winterfuels.cfm">20 percent of New England homes </a>use wood for heating, according to a National Geographic report. Although it may be a cheaper alternative, wood burning stoves and fireplaces<a href="http://www.epa.gov/burnwise/energyefficiency.html"> release more emissions of fine particles </a> than other home heating methods, according to the EPA. Burning <a href="http://www.epa.gov/burnwise/bestburn.html">good wood in an efficient burner</a> lowers toxic emissions and lost energy. Oh, and always have working smoke and carbon monoxide detectors handy. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • Hydroelectric - 35 Percent

    Almost all of the current hydroelectric power plants in the U.S. were <a href="http://www.eia.gov/energy_in_brief/article/hydropower.cfm">built before the mid-1970's</a>, but it's still the highest producing renewable energy source in the country. In 2011, 8 percent of all power created in the U.S. came from hydroelectric sources, but it's also one of the most geographically dependent sources of energy. The Pacific Northwest gets more than half of all power via hydroelectric due to prime geography. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>

  • How To Really Go Renewable

    Watch this TED talk on the missing link in the future of renewable energy.