Mariposa Biomass Project
Demonstrating a 2.4 MW forest waste-to-energy facility using the innovative "WoodRoll" technology.
Mariposa County Resource Conservation District (MCRCD)
Recipient
Mariposa, CA
Recipient Location
4th
Senate District
8th
Assembly District
$307,312
Amount Spent
Active
Project Status
Project Update
To complete this project within the EPIC grant term, the Mariposa Biomass Project team requested and was approved to change the technology provider to West Biofuels. West Biofuels designed a 3 MW thermal oil plant within the Conditional Use Permit conditions of the previous plant and within the same footprint. The Mariposa Planning Commission approved the project's Conditional Use Permit, leading to the provision of its grading and building permit. The recipient aims to start construction in the third quarter of 2026. The project drew funds to make progress with the site preparation using the additional grants received in 2024: a U.S. Fire Service Wood Innovations grant, a CAL FIRE Wood Products and Bioenergy grant, and a US Department of Energy Office of Clean Energy Demonstrations grant.
In the first quarter of 2026, grading activities began at the deployment site while waiting for PG&E’s approval of its System Impact Study and Interconnection agreement. Equipment purchases and construction is expected to start on the third quarter of 2026.
The Issue
About 65% of the homes in Mariposa County are at the 2,000 to 6,000 ft. elevation range in the conifer or mixed conifer zone and are at risk of wildfires and falling trees. There is a need to manage excess vegetation and a need to demonstrate advanced technologies that can economically convert woody biomass while meeting emission standards. However, no commercially proven technology has the flexibility in both the feedstock and fuel outputs. Larger scale biomass plants have difficulty scaling to below a 3 MW size, while small-scale pyrolysis-based systems that use a reciprocating engine have high maintenance costs and low reliability and availability.
Project Innovation
This project is designing and constructing a thermal oil biomass-to-energy conversion facility for forest wood waste that will have a capacity of 3 MW annually and produce between 15,000 to 18,500 MWh annually of renewable, community-scale, grid-connected electricity. The project demonstrates and optimizes this forest waste bioenergy technology and assesses the performance characteristics and best practices when using wood waste from forest management as feedstock. The project is in Mariposa, California, often referred to as ground zero for the tree mortality disaster, and will use forest biomass obtained from high and very high severity fire hazard zones.
Project Goals
Project Benefits
The primary benefit for ratepayers is the cost-effective production of locally sourced renewable electricity, and associated emission reductions from avoiding disposing of forest waste in open burn piles. The project is in Mariposa, California, often referred to as ground zero for the tree mortality disaster – thus essentially all the fuel will be Senate Bill (S.B.) 11221 compliant and obtained from a high fire hazard zone. The project is in PG&E’s operating territory. The project intends to secure a power purchase agreement (PPA) from PG&E under the Bioenergy Market Adjusting Tariff (BioMAT) Program. The project has completed the preliminary interconnect study (Rule 21) for both the primary site and a backup site.
Environmental Sustainability
The proposed facility will provide community and state benefits, including forest ecosystem protection (due to removal of dead trees and excess forest growth that can lead to catastrophic wildfires), watershed protection, and air quality improvements. Benefits include low-carbon, reliable energy, reduced carbon emissions, and a local market for biomass from forest thinning and vegetation management projects.
Key Project Members
Melinda Barrett
Subrecipients
West Biofuels, LLC
Mariposa Bioenergy LLC
Match Partners
West Biofuels, LLC
Mariposa County Resource Conservation District (MCRCD)
Mariposa Bioenergy LLC
