The Mariposa Biomass Project

If you are new to this site, start with the recently updated FAQ. If you are looking for the latest news, read below. Older news is now in the News Archive.

Meetings: The Mariposa Biomass project meets every two weeks on Tuesdays at noon at the Offline Solar Office behind the Pony Expresso. Our next meeting is scheduled for Tuesday April 25th.

EPIC News! We have just been notified that we have received a $5 million EPIC grant for a demonstration biomass-to-energy project in Mariposa County. Here is a PDF document announcing the award. Not only that, we received the top score! Together with the $11 million in matching funds from our technology partner, Cortus Energy, we can now move forward on our project to restore forest health, pay for the removal of dead trees from around homes and public infrastructure and diversify our local economy with good, high paying jobs. Read the press release here. Next step: Use permit from the County including CEQA review and the PG&E System Interconnect Study.

Tree Mortality Presentation: On March 16th we presented our project the the Mariposa County Tree Mortality Disaster Mitigation Committee which included an animated video of the proposed Cortus WoodRoll facility and some preliminary site and grading plans. Here is a presentation with some of the new material that we presented there, including the animated video.

March 23rd Update: MBP continues to make substantial progress in developing this project. The application for a Conditinal Use Permit will be filed next week (the week of March 26th). The environmental assessment of the site is underway and engineers have been lined up to complete noise and traffic studies should they be required as part of the application. An engineering firm has been selected to complete the Electrical Inteconnect Application and MBP is expecting that application to be filed in early April.

Here is a link to our February 2017 progress report.

Do biomass power plants use a lot of water? We recently heard an objection to our project based on the assumption that a biomass power plant would necessarily use a lot of water. We have prepared a brief presentation on water use by biomass plants and will update the FAQ to address this issue. The quick answer is that many power plants, including some biomass plants, do use a lot of water, but our plant will not as we are using a very different technology for generating the electricity - a reciprocating engine rather than a steam turbine.

There is a recent article in Biomass magazine about our project.

We have updated the Slideshow to reflect recent developments.

Biomass Utilization, Energy, Air Pollution and Climate Change

Biomass in our forest can have many fates ranging from being burned in a wildfire to helping create clean green energy and reversing climate change.  Not all ways of using or disposing of biomass are created equal.  Methods that release the carbon in forest biomass as carbon dioxide (CO2) exacerbate climate change at a time we need to reduce carbon emissions.  Biomass left to decay in the forest releases much of the carbon as methane (CH4) a short-term greenhouse gas that is 105 times more warming than carbon dioxide while it is in the atmosphere (10.5 year half life).  Forest fires release carbon as both carbon dioxide and black carbon (soot) that also contributes considerably more short-term warming than carbon dioxide.

The table below ranks various biomass disposal techniques in terms of air pollution, i.e. particulates and NOx and carbon released to atmosphere.  In dealing with the current tree mortality problem, for the sake of public safety, we need to use every technique below, other than forest fires, or course.  Over time we should try to move to techniques lower in the chart that derive value from the biomass, and have the potential reverse climate change rather than exacerbate it.   Energy derived from dead trees replaces energy derived from fossil fuel sources, thus helping mitigate climate change. (This should be differentiated from cutting down living trees to produce biofuel, a questionable practice at best, from a climate change point of view.)  Obliviously converting the carbon in dead forest biomass to biochar that can sequester that carbon for thousands of years is the most promising approach and should be encouraged.

Is burning biomass contributing to global warming? Should burning wood or other biomass be considered clean, green renewable energy? 

There has been a fair number of news articles lately, such as this one on Climate Central, about the wood pellet industry and the fact that we are harvesting trees in the U.S. to make wood pellets for use as fuel in power plants in Europe and Asia. In fact the majority of “renewable energy” in Europe comes from burning wood, and according to Climate Central article, the power plants burning the wood are getting tax credits aimed at mitigating climate change, and yet the article alleges that those plants making climate change worse! The article claims that wood-based energy exploits a loophole that allows wood to be considered renewable to the detriment of our planet?

So why are we considering a biomass plant in Mariposa? Should we be shutting down all the biomass plants in the Central Valley that burn agricultural waste, e.g. orchard trimming, almond shells and peach pits because burning biomass is contributing to global warming? The answers to these questions are not simple and include analysis of the fuel sources and the alternatives for disposal of various biomass waste streams, and the fact that one does not need to burn the biomass and release all the carbon to make electricity. One can use other technologies that actually help reverse climate change rather than exacerbating it. The devil is in the details. So what is the truth and how does the Mariposa Biomass Project fit into all this? Click here to find out.

Questions or Comments:

For questions about the organization, contact the Mariposa Biomass Project at

For comments on the website: Steve Smallcombe at