Evaluation of new technologies on biomass and waste cofiring

The objective of this study is to determine analytically the actual potential of large-scale biomass-based electricity production technologies in the mid-term future in a large geographical area.A case study over a ten-year period was carried out for the United States state-by-state analysing potentials of commercial large power generation using fluidised bed technology.The time period is chosen to be consistent with the commitments of the Kyoto Protocol on greenhouse gas emissions.Technologies considered are (1) cofiring (CF) of biomass in existing coal fired power plants, (2) a new fluidised bed boiler for cofiring, (3) conversion of an existing boiler to fluidised bed combustion (FBC) and (4) an atmospheric biomass gasifier connected to existing boiler. All the concepts have been demonstrated and are in the commercial operation in Europe but their poor competitiveness has prevented a significant market penetration to date in the United States.Additionally, a novel concept of integra ting a flash pyrolysis unit to a fluidised bed boiler is evaluated.Cogeneration is also included in the study.Mill residues and municipal wood waste from construction, demolition and yard trimmings are the most low-cost fuels and they could generate in cofiring the electricity production capacity of 2000 MW and 8000 MW respectively.Agricultural and logging residues have large potential of 19000 MW and 6000 MW, but their costs are not so competitive.Dedicated energy crops and residues from silvicultural operations could manifold available resources in the future.Cofiring is the lowest-cost alternative for utilities to start use of biomass.Tax credits for cofiring during five years would make use of biomass in coal-fired boilers competitive 2000 MW with 0.5-cent/kWh-tax credit and 6000 MW with 1.0 cent/kWh.The willingness to invest is estimated to be small without obligations or high tax credits, because risks are large compared to benefits.FBC technologies are feasible if low-cost, low - quality fuels are available, SO2 or NOx emissions have been reduced, or boilers need repowering.A tax credit of 1.5 cent/kWh for 10 years would crate economic prerequisites for 8000 MW of atmospheric gasifiers and FBC boilers.Renewable portfolio standard (RPS) with a price level of 25 USD/MWh of renewable energy would create possibilities for the generation of 8000 MW by biomass, and with price level of 40 USD/MWh over 30 000 MW, and the probability of investments is estimated to be high.Possibility to increase cogeneration with very high over-all efficiencies in the forest industry is about 5000 MW, but special incentives for cogeneration would be needed.Tax credits could create active fuel markets for biomass and reliability of concepts could be tested, and learning curves would reduce investment costs.RPS-type of incentives would ensure the increase of renewable energy with a certain amount very effectively because operators are free to choose the most cost-effective measures for th em.Increase of the biomass-based electricity production could be 5% of the electricity demand and reduce 3% of CO2 emissions by 2010 based on low-cost biomass residues.