The newly-installed air-measurement devices.
In September, Greg Chapman and I made our second trip to Renewable Fuel Technologies (RFT) to continue work on measuring the energy and mass balances of RFT’s pilot-scale torrefier. The one-ton-per-day torrefier produces a charcoal-like product called bio-coal from wood waste by heating biomass to 300°C in the absence of air. The bio-coal can then be co-fired in a power plant with standard fuels such as coal or wood chips to generate renewable electricity. SERC’s measurements of the device will aid in designing the torrefier for mobile, stand-alone operation and optimizing the technology for commercial use in converting timber waste into very low carbon renewable energy. This work is funded by the California Energy Commission.
The newly-installed torrgas sample condenser.
During this visit, we installed new instrumentation on the pilot-scale torrefier to measure power, air and gas flows. Greg also designed, built, and installed a condenser to sample the condensable portion of the gas by-product of the torrefaction process, called torrgas, which is used to generate heat as a key part of RFT’s efficient design. An initial test run of the system using the new instrumentation was successful, and planning is now underway to procure and transport several tons of wood chips to RFT, which will be used in a series of torrefaction experiments under varying conditions to collect detailed data on the operating characteristics of the system.
A $95,000 California Energy Commission (CEC) grant enables SERC, in partnership with Renewable Fuel Technologies (RFT) of San Mateo, to continue experiments aimed at converting slash from logging and fuel reduction efforts into energy dense bio-coal. RFT has developed a pilot-scale, one ton per day torrefier which produces bio-coal from timber waste by heating biomass to 300°C in the absence of air. Bio-coal can be co-fired in a power plant with standard fuels such as coal or wood chips to generate renewable electricity.
This new project involves measuring the energy and mass balances in RFT’s pilot-scale unit. These measurements will aid in designing the torrefier for mobile, stand-alone operation and optimizing the technology for commercial use. Mobility is considered crucial if torrefier technology is to become commercially viable. A good deal of forest debris lies in remote, difficult to reach locations, generating high logistics overhead. By making biomass three times as energy dense, the mobile torrefier would provide a far more economical approach as well as a major incentive to commercial conversion of timber waste into very low carbon renewable energy.
The CEC also awarded SERC Faculty Research Associate Dr. David Vernon $94,993 to examine the use of sugars from biomass to offset fossil fuel use, increase efficiency and reduce emissions in combustion processes. This work uses plant-derived sugars in chemical reactions that consume waste heat to produce a hydrogen-rich gas that can be mixed with traditional fuels to promote more complete combustion. This process has the potential to replace up to 50% of the fossil fuel and to increase efficiency by as much as 25%. It could also reduce emissions of NOx by over 95% while maintaining or reducing emission levels of other pollutants. If successful, the technology developed from this work could be retrofit onto existing gas turbines and engines in power plants and gas pipeline compressor stations without requiring costly modifications to the existing systems.
Graduate Student Assistants Mark Severy and Billy Karis (left) and Faculty Research Associate David Vernon test aqueous phase reformation reactions.
Specifically, this project explores the use of aqueous phase reformation reactions that directly process sugars and operate at lower temperatures than the gas phase reformation reactions that are being investigated for waste heat recovery elsewhere. Sugars can be produced from virtually any cellulosic biomass, including waste resources such as forestry slash, lumber mill waste, crop residues, portions of municipal solid waste, yard waste, etc. By operating at lower temperatures, aqueous phase reformation has the potential to recover significantly more waste heat compared to gas phase reformation reactions.