The Mariposa Biomass Project

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

As explained below, last October our technology partner, Cortus Energy encountered a problem with char dust from the pyrolysis chamber collecting in the pipes that carry the pyrolysis gas from that unit, and went through a redesign to add cyclones to remove that dust from the pyrolysis gas and return it to the stream of char going to the gasifier. Cortus has produced weekly updates to document their progress in reconstructing, testing and commissioning the WoodRoll® system at Höganäs as a result of that redesign. These videos are available as blogs at the Cortus.se website, or we made a composite video with highlights from the various Cortus videos showing their continuing progress.


Our technology partner, Cortus Energy has been dealing with technical problems for several months now at their first full-scale plant at Höganäs, Sweden, and these problems have delayed completion of the critical Milestone 3 test involving one week of continuous operation. Originally these technical problems were thought to be associated with the design of the flare use to burn off excess gas during startup or generator failure, but it now seems that the real problem was fine dust particles of char from the pyrolysis stage in the pyrolysis gas that is used to heat the gasification stage. These particles not only deposit on the surface of the pipes carrying the gas, limiting the time of continuous operation, but also make combustion of the gas less controllable.

After careful study of the problem for several months, Cortus has decided to address this issue with a series of cyclones to separate the dust particles from the gas stream. The cyclones are designed especially for separating low density particles from a high temperature gas stream using CFD-analysis (Computational fluid dynamics). Although it will take several months for the cyclones to be manufactured and installed, Cortus is now confident that they will solve the pyrolysis gas dust problem and Cortus will be able to start Milestone 3 testing in March of 2021.

The October, early November, late November and December updates are available on the Cortus website with more details. 

The January update from Höganäs is also now available and it shows good progress in testing the six individual components of the WoodRoll® system with the full milestone 3 target, 7-day operation of wet biomass to compressed syngas, on track. Cortus states that the design phase of the system is now complete.

In the February update from Höganäs, Corus Energy reveals that their WoodRoll® plant there has now delivered Green energy gas (syngas) to the demonstration furnace at Höganäs AB for the first time. Since of the test showed good results, Cortus can now shut down the plant and proceed with the addition of cyclones mentioned above. More details are available in the February update on the Cortus website. 


Wildfires and managing the forests in the Sierra are not trivial problems with simple solutions, e.g. clear cutting is not the answer.   We need a range of management options to restore forest resilience so that our watersheds can provide wildlife habitat, the water we all need, and our forested areas can provide the recreational and economic activities so vital to our Sierra communities. 

The Sierra Nevada Conservancy, SNC, is a State agency established through bi-partisan legislation to initiate, encourage, and support efforts that improve the environmental, economic, and social well-being of the Sierra Nevada Region, its communities, and the citizens of California.  Recently SNC published a short document outlining the Key Issues facing the Sierra including fire, water, greenhouse gas reduction, biodiversity and community resilience.

The document recognizes the role biomass utilization and small-scale biomass-to-energy plants can play in economy of Sierra communities while reducing the greenhouse gas and air pollution compared to the open pile burning normally associated with forest management practices. 

The Mariposa Biomass project appreciates the SNC’s support of our project since day one, and their continuing support ever since with training on grant writing and good advice on many issues.


Cortus Höganäss September 2020 Update

Our technology partner, Cortus Energy, has posted their September update. Cortus seems to have made considerable progress on some of the technical issues that have caused the recent delays in getting to their Milestone 3 that requires 7 days of continuous operation at Höganäs.  The compressor for the syngas, pictured on the right, is now in operation and they believe they have overcome their technical problems with the flare, and the seals on the pyrolysis unit.  Syngas has been produced using char generated at Höganäs and it was of the expected high quality.  Please read their update for more details.


Cortus Höganäs August 2020 Update

The Cortus August update is now available on the Cortus website.

The July update was in Swedish only and therefore so not posted here.

From the August update: "After drying a lot of biomass and producing tons of char this summer, all subsystems of the plant have been in operation. Our focus is now to make sure these are operable to deliver necessary capacities, ensure availability on each subsystem and to operate all subsystems together at the same time. The aim of this work is to verify that our technology works in a robust and safe way.

Our testing program has continued during the summer, and even if we have made progress in many parts, we have also discovered some issues which caused further interruptions."


Cortus Höganäs June 2020 Update

The Cortus June update on progress at Höganäs is now available. It seems that all systems needed to dry, pyrolyze and gasify the woody biomass are now ready to produce high quality syngas, but they have encountered an issue important safety system – the flare that is used to burn off the pyrolysis gas and syngas if the syngas cannot be fully utilized. They are working with the Swiss flare supplier to resolve the issue and expect to be able to conduct the 7-day continuous operations test in the near future.


The Cortus website now has the May Report available in which they describe the first production of char at Höganäs by theWoodRoll® pyrolysis sub-process. This char is then milled and gasified in the gasification sub-process to produce the sysgas that is used directly for heating at Höganäs, or in the case of the Mariposa Biomass Project, will be fed into a piston engine-based generator for the production of clean renewable energy from sustainably harvested forest biomass.


The Cortus website now contains a Höganäs April 2020 update on the progress at Höganäs, including a image of the gas analysis from first syngas produced at that location.


Our technology partner, Cortus Energy, has recently updated their website with most pages now in English. The Cortus website now features a page on the Mariposa Biomass Project and a blogpost on the importance of our project entering the BioMAT queue. Also check out this informative animation about their their WoodRoll® Process.

We have updated the Slideshow to include some recent developments. 


Here is an article in Bioenergy International based on a recent press release by Cortus Energy on the Mariposa Biomass Project joining the BioMAT queue, and another article on the production of the first syngas at the Cortus Energy Plant at Höganäs.


First Syngas at Höganäs Plant

We are very pleased to announce that our technology partner, Cortus Energy, has now produced the first syngas at their Höganäs plant in Sweden; see their press release here.


Cortus Energy has reached MILESTONE 2 (3) in Höganäs. The plant is now technically completed and ready for hot operation.

Read the press release in Swedish and English here


The November update for the Höganäs plant is now available.


Video from Cortus Energy

Cortus Energy recently posted an interesting video in English about the company, their WoodRoll® process, and their first full-scale plant in Sweden. It is available here.


Mariposa Biomass Project Enters the BioMAT Queue

In our September 3rd press release, we announced that out technology provider and project partner Cortus Energy’s Board of Directors authorized the funds necessary for the MBP to enter the queue for a Power Purchase Agreement (PPA) with PG&E under the BioMAT program created by California law S.B. 1122. Today, September 17th, we are pleased to announce that this process has been completed and we are now in the BioMAT queue, an important first step in obtaining a Power Purchase Agreement with PG&E


Article About Wildfire Risk in California and Biomass Plants

A recent article in grist magazine examines the role that small-scale biomass plants might play in reducing wildfire risk and air pollution in California. The author, Nathanael Johnson, obviously spent a fair amount of time talking to both proponents and opponents of such projects including many major environmental organizations. Our project was interviewed and quoted in the article, which to us seemed balanced with arguments for both sides presented.


The September update for the Höganäs plant is now available:   

The September update from our technology provider and project partner, Cortus Energy, concerning progress on the first WoodRoll® biomass plant at Höganäs in Sweden, is now available. The WoodRoll® plant at Höganäs is using the syngas (synthetic gas) produced by the gasification of woody biomass to replace natural gas at a metal powder coating plant. Because the WoodRoll® produced syngas is high in hydrogen and burns very hot, it is suitable for industrial uses that require high temperatures.

The global economy is moving away from fossil fuels and towards renewable sources of energy such as wind, solar, hydro and biomass for the production of renewable electricity. It is also clear that we can use this renewable electricity for transportation, e.g. electric cars and trucks, as well as heating, cooling and cooking in our homes. Most of our industrial processes can be powered by renewable electricity as well. However, the thing often left out of plans for a renewable energy future is how to deal with processes such as making steel and cement that use a lot of energy, and electricity is probably not the most efficient way of achieving the temperatures needed. The use of hydrogen from biomass sources for industrial process requiring high temperatures is therefore an important part of converting our global economy to renewable energy.

Fortunately, the syngas produced by the Cortus WoodRoll® process, is not only suitable for use with reciprocating (piston) engine based generators as we will be using here in Mariposa, or creating biofuels such as aviation gas, but also as a syngas to replace natural gas in industrial processes requiring high temperatures as is the case with the Höganäs plant in Sweden. The Mariposa Biomass Project is proud to be part of bringing this important technology to North America.


Mariposa Biomass Project Press Release: On September 3rd, 2019, the Mariposa Biomass Project sent out a press release (available here) to the local on-line and print newspapers, based on good news contained in the press release from Cortus Energy below. After the months of delays, it is very good to have our project take the important next step of entering the BioMAT queue so that we can obtain a Power Purchase Agreement for the sale of electricity to PG&E. Please note the comments by our CEO, Jay Johnson on the positive impact of this project on our community.


Cortus Energy Press Release about the Mariposa Biomass Project proceding to enter the BioMAT Queue and obtain a 20 year Power Purchase Agreement for sale of electricity


June, July and August updates for the Höganäs plant are now available


May 2019 update 

The Mariposa Biomass project has recently received several pieces of encouraging news:

Wood Innovation Grant: The Mariposa Biomass Project was successful in receiving a $250,000 Wood Innovations Grant from the US Forest Service. These funds will be used to complete remaining permitting and pre-construction work for a group of four small-scale community biomass plants throughout the Sierra.

Cortus Energy to purchase Mariposa Property: In their 1st Quarter financial report to shareholders, Cortus Energy announced that they would purchase the properties necessary to complete the installation of the Cortus WoodRoll® biomass-to-electricity here in Mariposa County, and are making payments accordingly. The properties are currently owned or leased by the non-profit Mariposa Biomass Project.

PG&E and the BioMAT program: Although PG&E is still in bankruptcy, they are again participating in the BioMAT program, honoring existing Power Purchase Agreements (PPA), and it is again possible for new projects to enter the BioMAT queue and obtain PPAs. Cortus Energy has indicated that they will have the funds for our project to enter the BioMAT queue in July. This in an important step for our project in terms of fulfilling a milestone in our EPIC grant with the California Energy Commission. It is also key to assuring potential investors of a reliable 20-year revenue stream at a favorable price.


May update for the Höganäs plant is now available.


Slideshow Updated 

The slideshow in the navigation bar has been updated to include new information about the project status, the project site, the Cortus WoodRoll® technology and a comparison with some of the technologies we have considered for our small-scale biomass plant.


Update on Current Status  

The Mariposa Biomass Project is moving forward, but for the last several months has been in a “holding pattern” based on two issues, delays in the construction of the first plant in Sweden and the PG&E bankruptcy

Delays in the Swedish WoodRoll® Plant The first issue is that our technology provider, Cortus Energy is building the first WoodRoll® biomass plant in Höganäs Sweden and construction and operation of that plant is currently about six months behind schedule. Successful operation of the Hoganas propject is a prerequisite to financing of the Mariposa project.  The Höganäs plant will process woody biomass to produce a synthetic gas or syngas that will replace the use of natural gas or methane in a steel mill for Höganäs AB in Sweden. According to Cortus, the six-month delay was caused by engineering changes and subsequent late deliveries of piping to the site.

Although delayed by six months, the Höganäs plant is now moving forward as can be seen from the recent updates from the Cortus in December, January, February, March, April  May and June. These reports are available in Swedish on the Cortus website and have been translated into English for our use.

Project Financing The Mariposa Biomass Project is also working with Cortus to find additional partners for financing and potential operation of the Mariposa biomass-to-energy plant. As part of this effort we have generated a document promoting the fact that our project is located in an Opportunity Zone - a new national community investment tool that connects private capital with low-income communities across America. Opportunity Zones provide a tax incentive for investors to re-invest their unrealized capital gains into dedicated Opportunity Funds. Learn more about Opportunity Zones here.

The Mariposa Biomass Project is also working with Cortus Energy to explore the possibility of actually building the various modules involved in the WoodRoll® process here in California rather than in Sweden as a way of reducing manufacturing and transportation costs.

PG&E Bankruptcy The second factor that has our project in this holding pattern is the bankruptcy declaration by PG&E. The financial basis of our project is based on selling the electricity we produce to PG&E at a favorable rate, as mandated by State law, S.B. 1122 and the BioMAT program. We are confident that when this bankruptcy is resolved the utility will be bound by the same law to purchace the electricity we produce via a Power Purchase Agreement or PPA. However, until the situation is resolved no new contracts or PPAs are being signed by PG&E, thus the need to wait until this situation is resolved.

Once the Höganäs plant is operational and the PG&E bankruptcy is resolved, we should be able to move quickly. In the meantime, we are working closely with the California Energy Commission to assure that we don’t spend our EPIC grant funds on equipment while the above issues are unresolved.


Conditional Use Permit Appeal Rejected by Board of Supervisors.

An appeal of our Conditional Use Permit was heard before the Board of Supervisors on July 10, with the meeting continued to July 17th. On the 17th, the Mariposa Board of Supervisors voted, 3-1 (1 recused) to reject the appeal and uphold the decision of the Planning Department and Planning Commission to approve our project.


A brief history of the BioMAT program and the Mariposa Biomass Project

If you think that small-scale biomass plants used to turn sustainably harvested forest biomass into electricity are controversial, or increase air pollution, you may not know that the State Senate bill, S.B. 1122 that incentivized these projects passed the State Senate 38-0 and that every air pollution district in the state encourages these biomass plants as they reduce air pollution. Learn more here: A brief history of the BioMAT program and the Mariposa Biomass Project


FAQ responding to incorrect and misleading information about the Mariposa Bioenergy Plant.


June 2018 Update from CEO Jay Johnson: Current information about the status of the project is available here.


$5M EPIC Grant Final Approval:  On March 21st the Mariposa County Resource Conservation District and the Mariposa Biomass Project attended a meeting of the Board of Governors of the California Energy Commission. The first regular agenda item for the meeting was the formal approval of the $5 million EPIC grant to support the construction of a biomass-to-energy plant here in Mariposa County. The Governors approved the item 4:0 and said that they were please to fund such a fine project that would help mitigate the tree mortality disaster in the Sierra.


The Mariposa County Planning Commission approved the Mariposa Biomass Project Conditional Use Permit on February 23rd!


County Use Permit and CEQA Review: The Mariposa Biomass Project submitted our County Use Permit application in June of 2017. As part of that application and the California Environmental Quality Act (CEQA) review, we have conducted various cultural, biological, botanical, noise and traffic studies. An extract of those studies as well as other information on how our proposed biomass facility will affect the community can be found here.


In the subsequent months, the County Planning Department has asked for a number of additional studies in support of our permit application. Digital copies were sent to County as they became available. On December 19th, we submitted a paper copy of all of the studies to the County in a binder. With the draft CEQA Checklist written by the Mariposa Biomass Project team and our attorney Christiana Darlington, the paper submission was 580 pages. The Table of Contents is shown above. Digital copies of all submissions are available on the Planning Department website here.

The Planning Department has informed us that our project will go before the regularly scheduled Planning Commission meeting on the February 23rd in the Board of Supervisors chambers. We would appreciate it if all those that support our project plan to be at the meeting to express their views on the project and its benefits to our community.


Progress Report: Here is a link to our July-September 2017 Progress Report


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.


Progress Report:Here is a link to our April-June 2017 progress report.


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.


Progress Report: 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 admin@mariposabiomassproject.org

For comments on the website: Steve Smallcombe at stevesmallcombe@mariposabiomassproject.org