Last week, on the way to Mammoth Lakes for Sierra Solutions, I visited the biomass fueled cogeneration plant at the Northern Nevada Correctional Center, at Carson City, with Dave Atkins (Fuels for Schools) and Marcus Kauffman (Resource Innovations). The facility is in the red/brown building in the middle right of the above picture. We met with Jason Perock from the Nevada Division of Forestry and Ken Lyngar the plant manager. The facility is designed to produce 1 MW of electricity and to heat over 400,000 square foot of space. It can produce up to 30 MMBTU/hr heat.
The $8.5m plant opened in 2007 but has been plagued by operating problems and issues with sourcing fuel. However, it appears that the team has finally overcome these barriers and the system has run without problem for a couple of months producing 650 kW of electricity and heating most of the prison complex. Ken estimated that they are currently saving over $3500 per day compared to using the original natural gas system.
Inside the firebox of the Hurst Boiler
The system uses approximately 32 BDT of woody biomass every 24 hours (approximately 12,000 BDT/yr. Previously there was a reliance on construction and demolition (C & D) wood that was often being hauled long distances. Recently they have managed to develop local supplies from forestry contractors based in the Lake Tahoe area. The use of forestry chips results in a lower ash content compared to the C & D material – this is because there is less dirt and other contaminants in the material sourced from the forest. The forestry chip also handles better in the augers, conveyors and on the grate itself, whereas the C & D material was prone to bridging (or bird nesting) due to the fact that it is generally processed in grinders which give it a stringy structure. They intend to stockpile logs which they will chip throughout the winter season.
Forest sourced chips (L) vs ground C & D material (R)
The experiences associated with this project are invaluable and point to some key elements to consider before installing a biomass fueled system:
Technology – take care selecting the right technology for your energy need and appropriate to the available fuel supply. It may be better to buy a turnkey system rather than buying different components from different suppliers.
Fuel supply – consider where it will come from, at what price and in what form (chips, logs etc).
Involve the operators and maintenance people who will run the facility on a daily basis in the planning process – their insight and experience are invaluable.
Community and political support – consider issues such as air quality, truck movements, the impacts of forest management in addition to the potential costs savings.
Experience - An end user (heat or electricity customer) does not typically have biomass handling or logging experience; they just want to be able to flick a switch. You need to consider the supply chain in addition to the changed operations and maintenance routine. An Energy Savings Performance Contract with an Energy Services Company (ESCO) removes some of this responsibility but still offers cost savings. Ensure that performance contracts are appropriate and enforceable.
First cost consciousness is a big barrier in the public sector especially in today’s funding environment. You need to build a strong case to demonstrate the savings and societal benefits in switching to a biomass based fuel source.
It is great to see the project start to yield some of its potential. If they keep running with no problems they could have paid back the initial investment in 7 years or less with the additional benefit of providing a market for thousands of tons of woody biomass from fuels reduction projects on National Forest System lands in the Lake Tahoe Basin.
The steam turbine (generator is to the left)
Dave, Marcus and Jason discussing fuel specification