narrator: at the national renewable energy laboratory, or nrel, in golden, colorado, scientists and engineers working for nrel's biomass program are developing new ways to get fuel from plants. their goal is to replace a third of the united states' gasoline consumption with plant-based biofuels, or ethanol, by the year 2030. douglas: when you burn fossil fuels you're releasing carbon dioxide that was fixed in the earth millions of years ago when those ancient plants died. but when you're using a bio-based fuel like ethanol, you're actually only releasing carbon dioxide that was only recently fixed by the plants, and then the plants that you're growing for next year's crop will then fix that carbon back again. so the carbon cycle is nearly 100% complete. narrator: today, most of the ethanol produced in the united states comes from corn. the process is not much different from that of making wine or brewing beer. in large-scale plants all over the midwest the starch in corn kernels is convert to sugars which are then fermented with yeast. the end product of this fermentation is then distilled to

narrator: at the national renewable energy laboratory, or nrel, in golden, colorado, scientists and engineersof years ago when those ancient plants died. but when you're using a bio-based fuel like ethanol, you're actually only releasing carbon dioxide that was only recently fixed by the plants, and then the plants that you're growing for next year's crop will then fix that carbon back again. so the carbon cycle is nearly 100% complete. narrator: today, most of the ethanol produced in the united states comes from corn. the process is not much different from that of making wine or brewing beer. in large-scale plants all over the midwest, the starch in corn kernels is converted to sugars, which are then fermented with yeast. the end product of this fermentation is then distilled to separate the ethanol. but there are limitations to increasing the production of corn ethanol. corn is already a valuable commodity. it is an ingredient in many of the foods we eat and also used as feed for livestock. douglas: we think we can go to about 15 billion gallons of ethanol a year from corn kernels. but anyt