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Wood that we could

Biomass can tap our forests' resources, but some splinters accompany the harvest



Let's face it: We'll probably never be as badass as Sweden, the planet's top energy-recovery country. Only about 1 percent of Swedes' waste hits landfills, thanks to superb recycling programs and the fact that they burn not only their garbage, but also that of other EU countries, to create energy. Fancy co-generation plants, which produce both electricity and heat, break down more than 4 million tons of refuse annually with cleaner emissions than coal-fired plants, notes a recent TreeHugger posting.

This treasure from trash has inspired a new commodities market. It's not unlike the new bio-methane buses (or "poo-buses") in the U.K., which operate primarily off methane captured from area sewage-treatment plants. That methane's also being incorporated into the U.K.'s national grid for home heating.

Here across the pond, we aren't entirely devoid of waste-based energy ideas, even if we often lack the political will to execute them. One that's gained traction locally is using plant remains, namely scrap wood, as renewable "biomass" fuel.

As outlined by Colorado Springs Utilities, which received a $250,000 federal grant in 2009 for a woody biomass pilot program, the benefits include fewer emissions; carbon neutrality (since as wood decomposes, it releases CO2 anyway); and less ash to landfills. CSU also notes that it's a "dispatchable" renewable energy strategy (not reliant on the sun or wind), that it aids in thinning forests for fire mitigation, and that wood's a local resource, requiring less transport cost and energy.

Between January of this year and the May 5 fire at Martin Drake Power Plant, Utilities had achieved an 8 percent woody biomass blend with coal on its Unit 5 incinerator, the only one with a hammer-mill pulverizer, capable of crushing wood bits to the necessary size. Fort Carson was disposing of wood from its land and buying most of the energy back, toward its goal of net-zero energy and waste, says Utilities spokesperson Amy Trinidad. She also notes that Utilities was using Black Forest Fire wood.

Utilities has estimated it has a 20-year supply of wood within 75 miles of Drake, particularly from beetle-kill pine. But the fire, which originated near Unit 5, effectively suspended the program. And there's a new catch, currently being discussed as part of Utilities' Electric Integrated Resource Plan: As of April 1, 2015, the EPA won't allow any utility to burn wood due to chlorine regulations unless a scrubber is installed. (Roughly 0.1 percent can be released during combustion.)

Units 6 and 7 are already slated for scrubbers (also required by the EPA on all coal units by 2017), but unit 5's fate remains unknown in that feasibility study, says Trinidad.

"If we think woody biomass is good for our renewables portfolio, we'll need to look into new mill technology," she says, so that Unit 6 and 7's ball-mill pulverizers (versus 5's hammer-mill) could handle smaller wood chips. Realistically, she says, it would be 2017 at the earliest that we'd see a biomass program alive in some form.

But even with a limited trial, "it was looking positive for us and Fort Carson financially," she says.

Financial biomass benefit has also been proven at Beulah's Mountain Park Environmental Center, an education hub outside Pueblo that installed a biomass furnace in 2009. As detailed by maintenance director Shane Ewing, the park sits on 600 acres, all in need of thinning. At a rate of burning about 30 cords annually to heat MPEC's 14,000-square-foot retreat center that features a 70-person dormitory and 11 hotel-style rooms, he estimates MPEC also possesses a two-decade supply.

"Biomass works for us specifically since we have the natural resource on site," he says, adding that it keeps the outfit from having to use costly propane. That said, he questions whether biomass is ideal for all city folk.

Residential biomass furnaces start in the $4,000 range, and look like scaled-down versions of MPEC's two GARN 2000 boilers, which each place 2,000 gallons of water around a fire chamber loaded with logs up to 36 inches long. (Others may run on pellets). An air intake feeds the flames, which heat the water and secondarily burn the combustion gases (similar to coffee-roaster afterburners we detailed in "Coffee conundrum," Oct. 1); the hot water's pumped to radiant floor heaters around the building. Ewing says a full burn can be reached in 10 minutes, and MPEC tends to burn three or four fires on a cold day and a couple more in the evening to build up enough heat to last overnight.

Since most biomass units do require regular manual feeding, newer EPA-certified wood stoves for the home — technically biomass, minus the water system features — might be a better residential option as an adjunct to a standard gas furnace. Still, cities such as Montreal have moved to ban wood stoves by 2020, so even their fate remains uncertain.

Save us all, Sweden!

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