Pacific Institute

Bioenergy helps cut greenhouse-gas emissions


Source: Pacific Institute

Branches, stalks, and manure are waste no longer; bioenergy is part of the solution to reducing greenhouse-gas emissions.

A study released by the Green Power Institute, the Renewable Energy Program of the Pacific Institute in Oakland, California, reports that converting forest residues, agricultural and urban biomass waste, and gases from manure and landfills into energy helps reduce our greenhouse-gas emissions and replace a portion of fossil-fuel use.

Gregory Morris, Ph.D., author of the “Bioenergy and Greenhouse Gases” report, contends that the reduced greenhouse-gas emissions of biofuels should be expressed in the official tracking systems in a way that is usable in a greenhouse-gas compliance program, because the reductions in biogenic-greenhouse gases can be calculated as fossil-carbon emissions offsets.

Although the regulatory framework for reducing greenhouse-gas emissions is still being developed, the plan is for California’s biogenic carbon to be reported and tracked as a separate category of greenhouse gases than fossil-carbon greenhouse gases. As fossil-carbon emissions will need to be matched with emissions allowances, biogenic-carbon emissions will not have to be retired against emissions allowances.

“This makes sense,” Morris said, “because biofuels as renewable alternative-energy sources can help reduce our total greenhouse-gas emissions. First, they are carbon-neutral, so their use in energy production displaces the emissions we’d have from producing the same energy using fossil fuels. Second, bioenergy production actually reduces the greenhouse-gas emissions associated with conventional biomass disposal.”

Fossil-fuel combustion is the primary cause of global warming because it releases the vast amount of fossil-fuel carbon that is currently in geological storage into the active carbon cycle, where carbon exchanges rapidly among the oceans, plants, and atmosphere. Energy produced from biomass and biogas also emits carbon into the atmosphere, but this is carbon that is already part of the active carbon cycle and does not affect the total amount of greenhouse gases in the atmosphere.

With conventional disposal methods, like landfill burial and open burning, the carbon in wastes and residue is released as a mix of carbon dioxide and other more powerful greenhouse gases, such as methane. With bioenergy production, however, virtually all of the biomass carbon is released as carbon dioxide. “By releasing more carbon as carbon dioxide than methane, bioenergy production reduces the warming potential of greenhouse-gas emissions,” said Morris. “Our analysis shows that concentrations of biogenic greenhouse gases in the atmosphere right now are lower by 65 million tons of CO2 equivalents than if the California biomass energy industry had never developed.”

The modern California biomass energy industry has been operating for more than 25 years, growing from an effort by the sawmilling industry to reduce its air pollution into a crucial component of the state’s solid-waste-disposal infrastructure. Between 1980 and 2006, some 100 million bone-dry-tons of biomass have been diverted from the state’s landfills or from open burning and approximately one million acres of forest land have been treated for wildfire risk reduction because of the operations of the industry. As energy production from forest residues contributes to forest health and fire resiliency, it also increases the amount of carbon that remains stored on a sustainable basis in the earth’s forests.

Creating energy by converting biogas from existing landfills and manure from the dairy cattle industry, and by converting biomass from forest management and agriculture and urban residues, provides more than carbon-neutral energy sources. All of the alternative disposal options for these biomass residues, from decomposition to burial in a landfill to open burning, produce higher levels of biogenic-greenhouse-gas levels than their use for electricity production.

These greenhouse-gas benefits are provided in addition to the benefit common to all renewable energy production: avoiding the use of fossil fuels. The value of the greenhouse-gas offsets that are expected to become available in the next several years should improve the competitiveness of energy production from biomass and biogas resources in the marketplace of the future.

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