Dairy methane digesters are among the most cost-effective investments California can make to reduce greenhouse gas emissions and help achieve its climate change prevention goals, according to a new study by Ramboll Environ.
The study examines how cap and trade auction proceeds are being invested by the California Air Resources Board.
Projects currently funded by the state provide a return on investment ranging from as low as $2 to as much as $1,250 per metric ton of carbon dioxide equivalents reduced, the study says. Dairy digesters represent one of the most cost effective investments of state funds with a rate-of-return of just $7 per ton of reduction.
By destroying methane, a short-lived climate pollutant, dairy digesters can help California's efforts to address climate change, the report says. When these short-term investments are factored in, the cost per ton of reduction is closer to $2, which makes it even more cost effective.
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Speaking at COP21 in Paris earlier this month, California Governor Jerry Brown said that tackling short-lived climate pollutants (SLCPs) "is probably the most immediate challenge, and the most important thing to do leaving this conference." This declaration follows his announcement last September that California was launching an aggressive effort to reduce methane emissions and other SLCPs.
The Governor's emphasis on the importance of reducing SLCPs is backed by the University of California's Climate Solutions Group, which identified SLCP curtailment as the number one "science solution" for reducing greenhouse gases, and highlighted the value of bio-methane as a clean energy source.
Methane, which over 20 years has about 72 times more heat-trapping ability than carbon dioxide, comes from a variety of sources and is responsible for about 20 percent of California's greenhouse gas emissions.
Increasingly, stories are arising of enterprising dairy farms, from Canada to New York to the Pacific Northwest, putting their mounds of manure to good use — turning it into biogas with the help of anaerobic digestion technology. After recognizing the economic and environmental benefits and potential for biogas systems on dairy farms in the US, the White House last year released a Biogas Opportunities Roadmap. Biogas systems — which recycle organic material, including cow manure and food waste, into valuable co-products such as renewable energy, fertilizer, separated nutrients and cow bedding — offer a wide range of potential revenue streams, creating jobs and boosting economic development for communities.