After rolling out a wind-powered renewable energy option in July called Renewable Choice, Boone Electric and its parent cooperative have switched from buying wind power to burning low-sulfur coal mixed with walnut shells.
Associated Electric Cooperative, which serves Boone Electric, bought about 3,000 tons of landfill-bound walnut shells and is using them to produce about 3.8 million kilowatt-hours of electricity at the Chamois power plant, along the Missouri River about 30 miles east of Jefferson City.
With the average Boone Electric household using about 1,000 kilowatt-hours per month, burning the walnut shells could power 3,800 homes for one month.
The waste walnuts came from Hammons Products Co. of Stockton in southwest Missouri. The world’s leading producer of walnuts had a large stockpile of walnut shells when a tornado damaged several buildings in May. The shells became contaminated with debris, making them unfit for sale to other companies that use them as abrasives, a filler in certain wood glues and filtering applications in the oil industry.
Burning walnut shells is nothing new; power companies on the West Coast have made electricity with walnut shells since the early 1980s. Walnut shells are classified in a group of fuels called biomass. Biomass fuels are any plant-derived organic matter available on a renewable basis, according to the U.S. Department of Energy.
Chris Rohlfing, manager of member services for Boone Electric, said that while walnut shells may seem inexpensive, they are still more expensive than coal in terms of generating electricity. It takes about 13 percent more shells, by weight, to make the same amount of energy that coal produces, Rohlfing said. In addition,walnuts have a higher transportation and handling cost than the coal, he said.
On the other hand, Rohlfing said, walnut shells burn cleaner because they have only one-fifth the amount of sulfur than low-sulfur coal.
Boone Electric in July began offering its 24,000 customers wind power for an extra 3 cents per kilowatt-hour. The walnut energy being bought from Associated is less expensive: 2 cents per kilowatt-hour. Boone Electric sells the renewable power in 100 kilowatt-hour blocks with a required one-year commitment. One block now costs $2 extra per month.
In July, Boone Electric set a goal of getting 1 percent of its customers — or about 240 people — to buy renewable energy. So far, Rohlfing said Boone Electric has 60 customers purchasing a total of 187 blocks of renewable energy.
“Most people are purchasing between three and four blocks of energy,” he said.
So what happens when the walnut shells are gone?
“We’ve got walnut shells for quite a while,” said Mary Southworth, an Associated Electric spokeswoman.
Looking in the long term, Rohlfing said that Boone Electric can convert lots of things into energy, such as feed grain that has become spoiled and is no longer suitable for feeding to animals. Such grain is perfect for burning because it still has energy, he said.
“It’s better to make energy than put it in the landfill,” Rohlfing said.