For Students Engineering Design in Oregon Science Classrooms Page 3 of 3

For Students Engineering Design in Oregon Science Classrooms Page 3 of 3

Article Handout for Biofuel from Algae

Does Using Algae as Fuel Make Economic and Environmental Sense?

Introduction

Algae, also known as phytoplankton, include more than a 100,000 different species, but they can be hard to define and scientists don’t all agree as to which organisms are algae and which ones are not. Part of the confusion comes from the fact that algae, like plants, make their own food by photosynthesis, but unlike most plants, they don’t necessarily grow in the ground. Most algae float in water (phytoplankton cannot move on their own. Instead their mobility comes from wind, currents, and tides.), but some species live in the soil or in snow and some have even been found floating in clouds. The range in size among algae species is equally diverse. Some are single cells called diatoms, so tiny they can only be seen in a microscope. Other species, such as kelp, can grow up to 200 feet tall. Even though some scientists might argue about what should be called algae, everyone agrees algae are one of the most important life forms on Earth.

Algae are vital to the planet; they form the basis of most food webs in salt and freshwater bodies. Since they obtain their energy through photosynthesis, algae also remove large amounts of carbon dioxide from the air and replace it with oxygen. Some estimate that up to 87% of the world’s oxygen comes from algae. Humans eat algae, too, especially in counties like China and Japan, where it is consumed raw as a vegetable, added to salads and soups or, in the case of red algae, dried in sheets called nori and used to wrap sushi. Additionally, algae can be used as an agricultural fertilizer and algae extracts are found in medicines and cosmetics.

One of the most exciting new uses of algae is to create biofuel for cars and machines. Many scientists believe biofuel made from algae is our best option for an alternative energy source—some estimates say that with current resources, the U.S. could produce about 600 million barrels of algae-based biofuel per year (about 1/12 of the current annual consumption). Currently, scientists are researching which algae would yield the most oil, and which regions would be best for growing (hot and humid conditions are best). Water is also a concern, because some algae need saline water, and some need freshwater—and not all regions have these in ample supply.

Photosynthesis and Biofuel Production

6 CO2 + 6 H2O è C6H12O6 + 6O2
(Carbon dioxide) (Water) (Glucose) (Oxygen)

Plants produce the energy they need by using energy from light to convert water and carbon dioxide into glucose sugar. In doing so, plants increase the amount of oxygen in the atmosphere and reduce the reduce the amount of carbon dioxide.

There are currently two effective ways to obtain biofuel from algae. First, the sugars produced by algae can be fermented to produce ethanol—which you will find mixed into most of the gas you buy today, commonly from corn. However, the algae also convert some of the sugars to oils or lipids. These lipids can be extracted and processed into biodiesel, as the alternative way to produce biofuel from algae.

Additional Reading—Magazine Article

Pond-Powered Biofuels: Turning Algae into America's New Energy

Just three years ago, Colorado-based inventor Jim Sears shuttered himself in his garage and began tinkering with a design to mass-produce biofuel. His reactor (plastic bags) and his feedstock (algae) may have struck soybean farmers as a laughable gamble. But the experiment worked, and today, Sears' company, Solix Biofuels, in Fort Collins, is among several startups betting their futures on the photosynthetic powers of unicellular green goo.

The science is fairly simple: Algae need water, sunlight and carbon dioxide to grow. There are two ways to obtain biofuel from algae:

1. The glucose sugar and other sugars produced by the algae can be fermented to produce ethanol.
2. The algae convert some of the sugars to oils or lipids. These lipids can be extracted and processed into biodiesel.

The reality is more complex and can also be expensive to set up and operate. The algae need the right conditions to grow and there’s always the risk of invasive species.

Solix addresses these problems by containing the algae in closed "photobioreactors"—triangular chambers made from sheets of polyethylene plastic (similar to a painter's dropcloth)—and bubbling supplemental carbon dioxide through the system. Eventually, the source of the CO2 will be the exhaust gases from power plants and other industrial processes, providing the added benefit of capturing a potent greenhouse gas before it reaches the atmosphere.

Given the right conditions, algae can double its volume each day. Unlike other biofuel feedstocks, such as soy or corn, it can be harvested day after day. Up to 50 percent of an alga's body weight is comprised of oil, whereas oil-palm trees—currently the largest producer of oil to make biofuels—yield just about 20 percent of their weight in oil. Across the board, yields are already impressive: Soy produces some 50 gallons of oil per acre per year; canola, 150 gallons; and palm, 650 gallons. But algae is expected to produce 10,000 gallons per acre per year, and eventually even more.

"If we were to replace all of the diesel that we use in the United States" with an algae derivative, says Solix CEO Douglas Henston, "we could do it on an area of land that's about one-half of 1 percent of the current farm land that we use now."

Solix plans to complete its second prototype by the end of April and to begin building a pilot plant this fall. That plant will take advantage of CO2 generated from the fermentation and boiler processes of New Belgium Brewery, also in Fort Collins. The company's initial target is to be competitive with biodiesel, which historically sells for about $2 per gallon, wholesale. They believe they can reach this goal within a few years, and are ultimately aiming to compete with petroleum.

John Sheehan, an energy analyst with the National Renewable Energy Laboratory (NREL) in Golden, Colo., believes these goals are within reach. "There is no other resource that comes even close in magnitude to the potential for making oil," says Sheehan, who worked in the lab's algae program before it was shut down by the Department of Energy. One of algae's great strengths, Sheehan adds, is its ability to grow well in brackish water. In the desert southwest, where much of the groundwater is saline and unsuitable for other forms of agriculture, algae can proliferate.

GreenFuel Technologies Corp., based in Cambridge, Mass., is focused on cultivating algae that can produce high yields of both biodiesel and ethanol. There are more than 100,000 strains of algae, with differing ratios of three main types of molecule: oils, carbohydrates and protein. Strains of algae high in carbohydrates as well as oils produce starches that can be separated and fermented into ethanol; the remaining proteins can be turned into animal grains. GreenFuel hopes its pilot plant will see initial yields of 8000 gallons of biodiesel and 5000 gallons of ethanol per acre of algae.

The main focus now, says Cary Bullock, GreenFuel's president and CEO, is figuring out "how to grow algae fast enough and cheap enough that it makes sense economically. That's not easy to do."

With the science well in hand, the degree to which algae-based biofuels can replace petroleum—or the limited acreage of traditional feedstocks—rests upon that bottom line. Once the technology hits the ground, will a commercial-scale facility be on par with petroleum? Says Bullock: "You don't know until you've actually built the thing."

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Written by Amanda Leigh Haag; published in Popular Mechanics (2007, March 29). Retrieved from http://www.popularmechanics.com/science/energy/biofuel/4213775