After more than 15 years of R&D, West Biofuels (WBF) in Woodland is building its first two commercial scale plants to convert ag and forestry residues into electricity.  It has plans to develop many more as these first two prove their commercial viability and as they widen the number of valuable products they could produce.  We recently sat down with COO Dr. Matt Summers to get the details on what has been happening.  

WBF has been getting increased attention because of its focus on conversion of forestry waste to valuable products at a time when the California wildfires of the last half-decade have made the need to clear the forests of underbrush continually and deal with the damaged timber much more urgent.  WBF began with some R&D contracts to build a “process development unit” that would allow them to “tinker” with various components and approaches to deal with a variety of urban, orchard, ag and forest high-cellulose wastes.  The original idea was to convert these wastes efficiently into a gas containing a mixture of hydrogen, carbon monoxide, carbon dioxide, and methane that could fuel a reciprocating engine-generator to make electricity.  While that looked simplest and most achievable on paper, that is not the way things worked out.  The prices utilities were willing to pay for power from renewable sources were falling and, as many have encountered, feeding an engine with the variable and mixed synthesis gas was just too hard on the engine.  

Then, two things changed that put WBF on the road to a commercial unit.  First, they switched to using a different technology for power production.  They now use an indirect-fired power generator—an organic Rankine cycle (ORC) system made by Turboden.  In an ORC, a fuel is burned to vaporize an organic working fluid (like in a steam boiler) that feeds a power turbine and is condensed.  It is a closed loop system, so the nasty stuff in the fuel doesn’t much matter.  It is less efficient than feeding an internal combustion engine, but the savings in maintenance more than justify the switch.

Second, in a moment of foresight the California Legislature passed the Bioenergy Market Adjusting Tariff (BioMAT) law requiring utilities to pay a very favorable fixed price for electricity derived from biomass in small generators less than 5 MW in size up to an aggregate of 250 MW (Public Utilities Code § 399.20).  For the IOUs, this Feed-In Tariff (FIT) operates as a “must-take” contract in its portfolio. If the participant generates the power, the IOU must take it and pay for it. Electricity generated as part of the BioMAT program counts towards the utilities’ RPS and resource adequacy targets.  Small-scale bioenergy projects can be procured in three categories with allocations and prices set by the CPUC:

Table 1. BioMAT Allocation Summary in 2020

These fixed prices are about four times what power from solar and wind farms receive.  BioMAT is a huge boost for these favored forms of waste-to-energy.  

With these two changes, WBF has moved to market a 3 MW scale biomass-to-electricity within California with a plan to drive down costs over time, add more technology, and open up a wider market.  WBF has signed contracts with two entities to build these plants.  One is under construction in Williams and will use rice hulls as a feedstock getting the $183.72/MWh FIT.  Another is near Burney in Shasta County, with forestry residue feedstock (getting the $199.72/MWh FIT), and is awaiting the start of construction.  Each project costs about $25 million, but is expected to generate $85 million in revenue over 20 years.  The Burney plant also has the option of diverting output to the production of as much as 6,000 tons/year of biochar, used for filtration, as a soil amendment or an asphalt additive at $80-100/ton as an added or optional source of revenue.  Now WBF is seeking financing and investment to support another half-dozen of similar plants while there is still headroom under the 250 MW cap on BioMAT projects. 

Knowing that the 250 MW California market may represent a market for only a handful more of their first commercial plants given the number of other competitors, WBF is continuing to “tinker” to see what would widen its customer appeal (and the process development unit has gotten much bigger).  The push for now is to feed the synthesis gas to a catalyst bed to create liquid chemicals and fuels.  These products generally have a higher value than electricity outside of the BioMAT market, improving the economics of the process.  WBF is looking at two catalyst paths.  The first, done through contracts with the California Energy Commission, is to focus the output on mixed alcohols and methane.  WBF has found that it can make a product stream that has half the energy in the mixed alcohols and half in the methane fraction.  Both can be sold directly.  The alcohols include butanol, n-propanol (the straight chain version vs. isopropanol), and ethanol.  All three have good commercial markets, especially the n-propanol which is used as a solvent for inks as in ink-jet printers.  There is also a remaining gas fraction that can be burned to make electricity.  

The second approach, funded by the DOE, is to produce jet fuel and diesel through a Fischer-Tropsch-type catalyst supplied by an Austrian partner.  Those types of catalysts are relatively non-selective and produce a witches’ brew of products.  For WBF, only about 20% of the feedstock energy content ends up in jet fuel and diesel.  There is a substantial quantity of linear waxes as well, plus waste gases that would go to an ORC power plant.  The objective of the DOE contract is to figure out how to increase the yield of the jet fuel/diesel fraction and to explore how the waxes could be used in a standard oil refinery to increase the renewable content of motor fuels or lube oils, possibly by using spare Fluidized-bed Catalytic Cracking (FCC) capacity.  Adding a renewable feedstock to the refinery would help get a better Low Carbon Fuel Standard score, avoiding some of the penalties for being above the maximum allowed by CARB.  That incentive could make the WBF plants economical beyond the boost they get from the BioMAT prices.

Matt has always wanted to get to the point where they were building dozens of plants and making a real impact.  With these first two plants, he is excited to see that dream starting to become real even though it took fifteen years.  The tinkering continues. 

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