The stated purpose of the HR 6 Energy Independence and Security Act of 2007 was “to move the United States toward greater energy independence and security, to increase the production of clean renewable fuels, to protect consumers, to increase the efficiency of products, buildings, and vehicles, to promote research on and deploy greenhouse gas capture and storage options, and to improve the energy performance of the Federal Government [emphasis added].”
As part of the effort to increase the production of clean fuels, the act states that by 2022, over 10 percent of US transportation fuel will be replaced by biofuels mainly coming from something besides corn. This is defined as cellulosic ethanol and fuels derived from feedstock other than corn starch, with a specific mention of using algae.
A new study released by researchers at the Department of Energy’s Pacific Northwest National Laboratory (PNNL) claims that algae could replace as much as 17 percent of transportation fuel as long as we’re smart about where algae is grown and how much water is used. “Algae has been a hot topic of biofuel discussions recently, but no one has taken such a detailed look at how much America could make – and how much water and land it would require — until now,” said Mark Wigmosta, lead author and a PNNL hydrologist. “This research provides the groundwork and initial estimates needed to better inform renewable energy decisions.”
Wigmosta and his co-authors provide the first in-depth assessment of America’s algal biofuel potential given available land and water. The study also estimated how much water would need to be replaced due to evaporation over 30 years. The team analyzed previously published data to determine how much algae can be grown in open, outdoor ponds of fresh water while using current technologies. Algae can also be grown in salt water and covered ponds. But the authors focused on open, freshwater ponds as a benchmark for this study. Much of today’s commercial algae production is done in open ponds.
The researchers found that 21 billion gallons of algal oil could be grown on land roughly the size of South Carolina, but would require an amount of water equivalent to a quarter of what the country currently uses for irrigated agriculture. However, this usage isn’t that different from most other biofuel sources.
Algae has several advantages over ethanol derived from corn: it can produce over 80 times more oil than corn per hectare a year, it isn’t a widespread food source, and it is a carbon-neutral source because algae consume carbon dioxide. Since algae also consume nitrogen and phosphorous, it could potentially grow in, and help clean, municipal waste water.
“Water is an important consideration when choosing a biofuel source,” Wigmosta said. “And so are many other factors. Algae could be part of the solution to the nation’s energy puzzle — if we’re smart about where we place growth ponds and the technical challenges to achieving commercial-scale algal biofuel production are met.”
Next up for Wigmosta and his colleagues is to examine non-freshwater sources like salt water and waste water. They are also researching greenhouse ponds for use in colder climates, as well as economic considerations for algal biofuel production.