cost effective

Plants Paying For Biofuels | Earth Wise

May 7, 2020 By EarthWise Leave a Comment

Biofuels are an important element in broader strategies to replace petroleum in transportation fuels like gasoline, diesel, and jet fuel. The idea is that biofuels recycle carbon by getting it from growing plants rather than from fossil sources. The biggest problem with biofuels is that they cost more than conventional petroleum fuels, so there is economic incentive to keep burning the fossil fuels.

One strategy to make biofuels cost competitive is to have the plants provide additional economic benefits beyond being a feedstock for fuel. This in principle can be done by engineering plants to produce valuable chemical compounds, or bioproducts, as they grow. Bioproducts include such things as flavoring agents and fragrances as well as biodegradable plastic. These bioproducts can be extracted from the plants and then the remaining plant material can be converted to fuel.

Researchers at Lawrence Berkeley National Laboratory recently published a study to determine what quantities of bioproducts plants need to produce to result in cost-effective biofuel production.

The study looked at a compound called limonene, which is used for flavoring and fragrance. They calculated that if this compound was accumulated at 0.6% of the biomass dry weight, it would offer net economic benefits to biorefineries. This corresponds to recovering 130 pounds of limonene from 10 tons of sorghum on an acre of land.

Such quantities are completely practical but, on the other hand, none of these substances are needed in huge quantities. Just six refineries could supply the world with limonene. So, fuel crops would need to be engineered to produce a broad range of bioproducts to enable a viable cost-effective biofuel industry.

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Making Biofuels Cheaper by Putting Plants to Work

Photo, posted September 28, 2019, courtesy of Michele Dorsey Walfred via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Bigger Is Better For Wind Energy

February 13, 2019 By EarthWise Leave a Comment

Bigger is almost always better for wind power. Bigger wind farms are better than smaller wind farms and bigger wind turbines are better than smaller ones.

The biggest turbines currently available produce nearly 10 MW of power, which is enough to supply over 2,000 homes with electricity. A wind farm with just a few of these turbines could produce enough electricity for a small town. A big wind farm, like the giant 1,550 MW Alta Wind Energy Center in California can generate enough power for a small city.

Vestas Wind Systems, an industry leader based in Denmark, has announced a 10 MW turbine that will be ready for installation in two years. The rotor diameter of the giant machine is 538 feet and the blades sweep out an area of 227,000 square feet, the size of nearly 4 football fields.

Not to be outdone, General Electric is developing a 12 MW offshore wind turbine that will stand 850 feet tall and sweep out an area of more than 400,000 square feet. GE estimates that its 12 MW turbine will achieve nearly twice the capacity factor of its 6 MW turbine.

Companies are building bigger and bigger wind turbines because they are more cost effective. The capacity factor, which is the actual energy production divided by the potential energy production, goes up as the turbines get bigger and more efficient. In terms of dollars spent to produce a given amount of power, larger windfarms are less expensive to build than smaller ones. A wind farm of 200-500 MW capacity is about 40% cheaper per MW capacity than a 25 MW wind farm.

When it comes to wind energy, there is no doubt that bigger is better.

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