Pressurized Oxidative Recovery of Energy from Biomass Final Technical Report
This study was conducted to evaluate the technical feasibility of using pressurized oxyfuel, the ThermoEnergy Integrated Power System (TIPS), to recover energy from biomass. The study was focused on two fronts—computer simulation of the TIPS plant and corrosion testing to determine the best materials of construction for the critical heat exchanger components of the process. The goals were to demonstrate that a successful strategy of applying the TIPS process to wood waste could be achieved. To fully investigate the technical and economic benefits of using TIPS, it was necessary to model a conventional air-fired biomass power plant for comparison purposes. The TIPS process recovers and utilizes the latent heat of vaporization of water entrained in the fuel or produced during combustion. This latent heat energy is unavailable in the ambient processes. An average composition of wood waste based on data from the Pacific Northwest, Pacific Southwest, and the South was used for the study. The high moisture content of wood waste is a major advantage of the TIPS process. The process can utilize the higher heating value of the fuel by condensing most of the water vapor in the flue gas and making the flue gas a useful source of heat. This is a considerable thermal efficiency gain over conventional power plants which use the lower heating value of the fuel. The elevated pressure also allows TIPS the option of recovering CO2 at near ambient temperatures with high purity oxygen used in combustion. Unlike ambient pressure processes which need high energy multi-stage CO2 compression to supply pipeline quality product, TIPS is able to simply pump the CO2 liquid using very little auxiliary power. In this study, a 15.0 MWe net biomass power plant was modeled, and when a CO2 pump was included it only used 0.1 MWe auxiliary power. The need for refrigeration is eliminated at such pressures resulting in significant energy, capital, and operating and maintenance savings. Since wood waste is a fuel with a high moisture and hydrogen content, it is one of the best applications for TIPS. The only way to fully utilize the latent heat is by using a pressurized system and the oxy-fuel approach allows for carbon capture and easier emission control. Pressurized operation also allows for easier emission control than atmospheric oxyfuel because presence of infiltration air in the atmospheric case. For the case of wood waste as the fuel however, the ability of TIPS to fully utilize the heat of condensation is the most valuable advantage of the process. The project research showed that titanium alloys were the best materials of construction for the heat exchangers. All other materials tested failed to withstand even brief periods in the harsh environment (high temperature, acidic, and oxidizing conditions). Titanium was able to survive due to the formation of a stable TiO2 passivation layer.
- Research Organization:
- M. Misra, University of Nevada, Reno, Reno NV; Alex Fassbender and Robert Henry, ThermoEnergy Power Systems, LLC., Hudson MA
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- DOE Contract Number:
- FG36-05GO85015
- OSTI ID:
- 915087
- Report Number(s):
- DOE GO85015; TRN: US200817%%242
- Country of Publication:
- United States
- Language:
- English
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