One of the more contentious sources of renewable energy is biomass - burning wood pellets instead of coal or natural gas to generate heat or electricity.
The controversy could grow in B.C, as wood pellet producers appear to be resorting to using more live whole trees to produce wood pellets for export, as opposed to just wood waste.
Two B.C. wood pellet producers - Pinnacle Renewable Energy Inc. (TSX:PL) and Pacific BioEnergy - are being singled out by Stand.earth in a new report that suggests that the companies are now using what appears to be live, whole trees.
"Wood pellets are obviously the worst and lowest use of our last primary forests in the interior," said Michelle Connolly, director of Conservation North, which has documented the use of whole trees at B.C. pellet plants.
"The B.C. government assured us that green trees would not be used in pellet plants, and clearly that's not true."
"The BC government has sold wood pellet exports as an opportunity to make use of waste, such as sawdust and slash piles," the Stand.earth report states.
"Using photos and satellite imagery of both of British Columbia's biggest pellet companies, Pacific BioEnergy and Pinnacle Renewable Energy, this investigation reveals with absolute certainty that wood pellets are being made from whole trees in British Columbia."
Typically, wood pellet producers in B.C. use sawdust from sawmills and other wood waste, from logging.
But as the demand for biomass energy has grown, especially in Europe, so has wood pellet production in B.C., at a time when the availability of fibre has been declining in B.C., and when sawmills are shutting down, reducing the amount of sawmill waste that was available.
Bioenergy production has grown substantially in Canada in recent years, driven by a demand, mainly in Europe, for biomass - i.e. burning wood pellets instead of coal or natural gas to generate electricity. In Germany, biomass accounts for about 8% of electricity generation, and in the UK it accounts for 11%.
Annual wood pellet exports from Canada increased by 73% in the last five years, according to the Canadian Energy Regulator.
Canada is now the second largest wood pellet exporter after the U.S., and B.C. is Canada's largest wood pellet producer. According to Stand.earth, there are now 14 wood pellet plants operating in B.C.
As sawmills shut down, in part due to a lack of fibre, less wood waste is available, so it may be that B.C. pellet producers are resorting more and more to harvesting "marginal" forests and diseased trees.
The question is whether those trees have any value for more high-value manufacturing, like lumber or pulp and paper.
"I think it's an open question whether there is enough wood waste or 'residuals' in existence to feed these plants," Connolly told Business in Vancouver. "Our concern, as an organization, is that there will be logging of standing forests to feed, basically, their vacuums."
Business in Vancouver has reached out to both companies, and the Ministry of Forests, for clarification on the types of trees being harvested for wood pellet production and has not yet received a response.
One company, Pacific BioEnergy, has harvesting rights to 25,000 cubic metres of timer in the Prince George Omineca Timber Supply Area.
"We saw rain forest trees in that pile," Connolly said. "So those are cedars, and other species.
"The government gave them the right to harvest in this area. It's not waste in the sense that the trees were dead and then they harvested them. Those were living, green trees that they harvested. Some of them even the leaves on them, if you look closely at some of those photos."
It may be that some of the trees harvested for pellet production were diseased. More than 341,000 hectares of forest in the Omineca Region are currently infested by spruce beetles, according to the B.C. government.
But even if they weren't diseased, but simply simply trees of marginal value, bioenergy is still considered by many sustainable energy experts to be preferable to fossil fuels for generating power, from a GHG mitigation perspective.
Some environmental and conservation groups claim otherwise, and there is a growing campaign, especially in Europe, to halt the burning of biomass for power generation.
From a climate change mitigation perspective, those campaigns are misguided, according to Mark Jaccard, a professor at the School of Resource and Environmental Management at Simon Fraser University.
"The use of bioenergy from sustainably managed forests and agricultural land can make an important contribution to rapid GHG reduction in many places, including BC," he said.
A number of environmental groups have lately claimed that biomass, when burned to generate power, is worse than coal, oil and natural gas. A similar argument has been made against natural gas - that it's as bad or worse than coal - a claim not borne out by credible GHG life cycle analyses.
The claim is based on some GHG calculations that have concluded that wood mass generates more CO2 than coal, when burned. That's because coal has greater energy density than wood, so more wood needs to be burned to generate the same amount of energy that burning coal would generate.
What those studies often fail to account for, however, is the amount of methane produced from the mining of coal.
They also fail to consider that coal doesn't grow back - trees do. As they grow, they take back up the CO2 that was produced in combustion.
The concern, however, is the deficit between combustion and regrowth.
"The payback time for this carbon debt ranges from 44-104 years after clearcut, depending on forest type - assuming the land remains forest," a recent article by John Sterman (MIT) et al in Environmental Research Letters says.
Jaccard said it's simply not true that biomass is as bad or worse than coal, and dismisses the concern that it takes decades for regrowing forests to recapture CO2.
"It is incorrect to claim that the GHG emissions from coal combustion is less than the GHG emissions from a sustainably harvested, energy-dedicated forest," he said.
"The latter causes no net increase in atmospheric GHG concentrations whether measured over one, four or 20 decades. The former (coal) takes carbon that was safely stored underground and puts it into the atmosphere where it causes climate change."
Hadi Dowlatabadi, a professor at the Institute of Resources, Sustainability and Environment at Simon Fraser University, said the GHG life cycle of wood is 15% to 20% that of coal.
"If someone tells you that the GHG emissions from burning pellets is higher than coal, I would ask them for clarification," he said.
While it may take trees decades to mature, that doesn't mean it takes that long for them to start absorbing CO2.
"A sustainably harvested forest for bio-energy is capturing the same amount of carbon each year ... that is released each year through combustion of a small percentage of the trees. Sustainable forest harvest for bio-energy is no different than sustainable forest harvest for wood fibre," Jaccard said.
"This explains why human biomass based energy systems did not increase atmospheric concentrations of GHGs over the past thousands of years in which humans have burned wood for energy."