Producing Electricity from the Biomass Waste (e.g. wood chips, poultry litter, s
ID: 1845374 • Letter: P
Question
Producing Electricity from the Biomass Waste (e.g. wood chips, poultry litter, saw dust, risk husk etc.) by using the micro-combined Heat and power (CHP) systems, and summarize the working principle of the overall system especially electricity generation part, capacity, emission level (e.g. CO_2, SO_x, NO_X, PM etc.) and cost of the micro-CHP system. "Measuring and prediction the major source of particulate matter and Health Impacts by using Computer Models or Instrumentations", (A)summarize different methods of measuring and prediction the major source of air pollutions in certain areas,Explanation / Answer
PROCESSES
– Biomass combustion is a carbon-free process because the resulting CO2was previously captured by the plants being combusted. At present, biomass co-firing in modern coal power plants with efficiencies up to 45% is the most cost-effective biomass use for power generation. Due to feedstock availability issues,dedicated biomass plants forcombined heat & power (CHP), are typically of smaller size and lower electrical efficiency compared to coal plants (30%-34% using dry biomass, and around 22% for municipal solid waste). In cogeneration mode the total efficiency may reach 85%-90%. Biomass integrated gasification in gas-turbine plants (BIG/GT) is not yet commercial, but integrated gasification combined cycles (IGCC) using black-liquor (a by-product from the pulp & paper industry) are already in use.Anaerobic digestion to produce biogas is expanding in small, off-grid applications.
Bio-refineries may open the door to combined, cost-effective production of bio-chemicals, electricity and biofuels.
TYPICALCOSTS
–Because of the variety of feedstocks and processes, costs of bio-power vary widely.Co-firing in coal power plants requires limited incremental investment ($50-$250/kW) and the electricity cost may be competitive (US$ 20/MWh) if local feedstock is available at low cost (no transportation). For biomass typical cost of $3-$3.5/GJ, the electricity cost may exceed $30-$50/MWh. Due to their small size, dedicated biomass power plants are more expensive ($1500-$3000/kW) than coal plants. Electricity costs in cogeneration mode range from $40 to $90/MWh. Electricity cost from new gasification plants is around $100-$130/MWh, but with significant reduction potential in the future.
STATUS
–Abundant resources and favourable policies are enabling bio-power to expand in NorthernEurope (mostly co-generation from wood residues), in the United States and in countries producing sugarcane bagasse (e.g. Brazil). Proliferation of small projects, including digesters for off-grid applications, is recorded in both OECD and emerging economies. Global biomass electricity capacity is in the range of 47 GW, with 2–3 GW added in 2005. Associated investment accounted for 7% of total investment in renewable energy capacity in 2005 ($38 billion excluding large hydro).
POTENTIAL&BARRIERS
–In the short term, co-firing remains the most cost-effective use of biomass for power generation, along with small-scale, off-grid use. In the mid-long term, BIG/GT plants and bio-refineries could expand significantly. IEA projections suggest that the biomass share in electricity production may increase from the current 1.3% to some 3%-5% by 2050 (IEA ETP, 2006), depending on assumptions. This is a small contribution compared to the estimated total biomass potential (10%-20% of primary energy supply by 2050), but biomass are also used for heat generation and to produce fuels for transport. Main barriers remain costs; conversion efficiency; transportation cost; feedstock availability(competition with industry and biofuels for feedstock, and with food and fiber production for arable land);lack of supply logistics; risks associated with intensive farming (fertilizers, chemicals, biodiversity)
FEEDSTOCK &PROCESSES
– Biomass resources include agricultural residues; animal manure; wood wastes from forestry and industry; residues from food and paper industries; municipal green wastes; sewage sludge; dedicated energy crops such as short-rotation (3-15 years) coppice (eucalyptus, poplar, willow), grasses (Miscanthus), sugar crops (sugar cane, beet, sorghum), starch crops (corn, wheat) and oil crops (soy, sunflower, oilseed rape, iatropha, palm oil). Organic wastes and residues have been the major biomass sources so far, but energy crops are gaining mportance and market share. With re-planting, biomass combustion is a carbon-neutral process as the CO2emitted has previously been absorbed by the plants from the atmosphere. Residues, wastes, bagasse are primarily used for heat & power generation. Sugar, starch and oil crops are primarily used for fuel production. Cheap, high-quality biomass (e.g., wood waste) for power generation may become scarce as it is also used for heat production and in the pulp & paper industry. New resources based on energy crops have larger potential but are more expensive. Technologies and cost of power and heat generation from biomass depend on feedstock quality, availability and transportation cost, power plant size, conversion into biogas (if any). If sufficient biomass is available, bio-power and CHP plants are a clean and reliable power source suitable for base load service.
TYPICAL COSTS
-Because of widely varying feedstocks and conversion processes, it is difficult to identify typical costs for biomass energy. The most economical approach is to use local biomass to avoid costly, energy-consuming transportation. Pelletisation can facilitate transportation but not all biomass readily forms pellets. New logistic routes have been developed to export pellets from Canada and Russia to Europe. The incremental investment cost of biomass/coal co-fired power plants range from $50 to $250/kW. Where feedstock is available at little or no cost, co-firing can reduce the electricity generation cost to as low as $20/MWh. If biomass is available at costs between $3.0-$3.5/GJ, then the electricity generation cost is higher than for typical coal-based electricity ($30-$50/MWh). This is however the most competitive near-term option for using biomass in power generation. The cost of electricity from dedicated solid biomass plants depends on technology, feedstock quality and cost, regional location, and size of the plant. Large-size plants require biomass transportation over long distances. Small size means higher investment cost per kW and lower electrical efficiency relative to coal plants. The capital cost of power plants with biomass gasification in the United States is about $2000-$3000/kW and generation cost is in the order of $90/MWh. Such plants may be cost-effective in CHP mode if connected to district heating schemes. The cost of biomass combustion steam cycle and CHP plants can be lower, with $1000/kW as the cost target. In Europe, the investment cost of biomass plants varies considerably from $1000 to $5000/kW, depending on plant technology, level of maturity and plant size . Assuming a delivered biomass price of $3/GJ, the generation costs from biomass gasification plants, even at higher efficiencies, are expected to be some $100-$130/MWh, more than twice the cost of fossil-fuel power plants. These costs may be significantly reduced by technology learning and then represent a low-cost option for renewable electricity.
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