Co-generation in small-town America

Ah, the irony. In San Andreas, CA, atop a possible earthquake of cataclysmic proportions, the town is adopting the latest distributed power generation technologies.

Someday soon, fuels from forests in this area south-east of Sacramento may power water plants, schools and even private businesses.

Bob Dean, a member of the board of directors of the Calaveras County Water District,has proposed portable cogeneration plants to both generate electricity and allow for more efficient use of wood-chip waste generated as local forests are thinned.

To Dean, burning that waste efficiently — without having to also burn diesel to truck it to a distant location — is the main point. And that’s because in his view, thinning overgrown forests is crucial to both the county water district and to the county.

“You need to manage the forests for water, because the most important resource in the Sierra Nevada is water,” Dean said.

And perhaps the biggest threat to Sierra watersheds is that wildfires will denude hills and strip their ability to slowly release runoff through the year. Yet National Forest and private forest managers alike have struggled to find ways to pay for necessary forest thinning to reduce fire danger.

A regional biomass plant scheduled to open later this year will solve the problem by providing a place to sell wood chips from forest waste. But the cost of trucking material around will eat into the money generated from wood-chip sales. Another option, Dean said, is to bring smaller, portable cogeneration plants close to where forests are being thinned. He said Calaveras County Water District plants could provide sites, since they are all over the county.

Such portable cogeneration plants are a recent technology in the United States. One of the very first so-called “modular” cogeneration plants was installed just three years ago at a walnut farm near Dixon. That plant burns walnut husks.

While such plants work well, they may not be economical in many locations because conventional electricity supplies are cheaper. That’s true in Calaveras County, where the water district and other government entities can get electricity for around 7 cents a kilowatt hour. “These systems start to work at 10 to 12 cents a kilowatt,” said Michael Weedon, executive director of BC Bioenergy Network, an agency that promotes biofuel energy systems in British Columbia.

Weedon said that in British Columbia, such small-scale biomass systems typically make economic sense for remote villages that are off the grid, or in cases where instead of making electricity, the cogeneration plant is used to produce heat or conduct industrial processes.

Still, energy costs are a moving target. County officials expect Calaveras Public Power Agency rates to gradually rise in coming years. And electricity in general is expected to cost more as oil and gas prices rise.

Weedon said it makes sense for those who live near a farm or a forest to expect that biofuels will, at some point, be a more cost-effective way to generate power.

“As we move to higher energy prices, we are going to see the development of what I call distributed power generation,” Weedon said. “The future of energy is going to be using low cost fuel sources on a proper sustainable basis.”

One firm that is already selling the technology is Colorado-based Community Power Corp. The company sells units mounted in 20-foot shipping containers that can be scaled to generate as little as 25 kilowatts an hour by burning roughly 50 pounds of fuel an hour.

“There’s no smoke, no residue,” said Robb Walt, the founder and president of Community Power. “The ash from the systems can be put right back in the garden.”

Walt said a 100-kilowatt system costs around $900,000.

He also said that his firm began installing the systems in portable steel shipping containers at the request of the military, one of his biggest customers.

In addition to heat and electricity, the portable co-generation systems also can be adapted to create liquid fuels. That means that communities with enough biomass available could potentially find energy independence.

Weedon said that’s why the government of British Columbia is putting millions into developing biofuel technology.

“If oil goes up to $150 (a barrel) and we start to tax pollution, you’ll see a lot more of these systems,” Weedon said. “And they will be very low cost and reliable. And secure. You won’t have to worry about sending your money out of the country. You can keep the money recirculating in your community.”