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Woody Biomass Background. Some History. 1970’s energy crisis results in government subsidies and research 1978 Public Utilities Regulatory Policy Act (utilities must buy energy from other producers)
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Some History • 1970’s energy crisis results in government subsidies and research • 1978 Public Utilities Regulatory Policy Act (utilities must buy energy from other producers) • During 1980’s, 6,300 megawatts of new wood fired capacity added (from 200 megawatts in late 1970’s)
And then… • 15 plants in CA alone are bought out and closed by utilities (to reduce costs associated with buying their power; Bergman and Zerbe 2005) • During the 1990’s not many new plants are built • It is believed that this is due to limited tax credits, increased conventional power capacity and overall low fuel costs
Now • Resurge in interest in biomass • Costs of energy is increasing • At the same time forest fires are increasing and forest fuels reduction needs have reached epidemic levels in some parts of the country • Great public interest in renewable energy • Public concern about CO2 etc.
US Energy Use (Scary Numbers) • About 100 Quads per year (DOE 2000) • A quad is a quadrillion BTU’s • 100,000,000,000,000,000 BTU’s is US use • 100,000,000,000 MMBTU’s
US Energy Use (Scary Numbers) • About 100 Quads per year (DOE 2000) • A quad is a quadrillion BTU’s • 100,000,000,000,000,000 BTU’s is US use • 100,000,000,000 MMBTU’s • Roughly the energy in 5,882,352,941 cords of aspen (just for comparison) • MN cut less than 3,000,000 cords of pulpwood in 2001
We will not be replacing all energy consumption with biomass, but it can be part of the picture
What is Feasible • About a 30% replacement of energy needs using ag residue/products and forest residue (Perlack et al. 2005) • Total forestland unutilized residue at this point (368 million dry tons) • Ag land (998 million dry tons) this is based on several changes that we will not discuss
Mike Math (obviously sort of gross measurements) • 13.8 mmbtu per oven dry ton • 368 million dry tons in US of wood residue • 5,078,400,000,000,000 btu • About 5 quads in all wood residue in US (about 5% of current use)
Outline • Benefits of wood • Problems • Potential users
1. Benefits of Wood • Domestic and LOCAL source • Renewable and carbon neutral (?) • Low heavy metal emissions • Extremely low sulfur dioxide emissions • Low ash with good reuse potential
Benefits of Wood • Domestic and LOCAL source • MN imports most of its energy (no coal, oil or gas deposits) resulting in large amounts of money leaving the state • The US has a low level of self-sufficiency in energy production • Renewable and carbon neutral (?) • Low heavy metal emissions • Extremely low sulfur dioxide emissions • Low ash with good reuse potential
Benefits of Wood • Domestic and LOCAL source • Renewable and carbon neutral (?) • Generally, wood is a renewable resource if the site is not degraded by the harvest • Wood uses CO2 to grow and harvest removes less CO2 than is stored on the site, generally carbon used equals or exceeds carbon harvested • Low heavy metal emissions • Extremely low sulfur dioxide emissions • Low ash with good reuse potential
Benefits of Wood • Domestic and LOCAL source • Renewable and carbon neutral (?) • Low heavy metal emissions • Mercury levels are very low in wood • Other heavy metals are low • Land application of ash is possible and common • Extremely low sulfur dioxide emissions • Low ash with good reuse potential
Benefits of Wood • Domestic and LOCAL source • Renewable and carbon neutral (?) • Low heavy metal emissions • Extremely low sulfur dioxide emissions • Generally there are very low levels of sulfur in wood • Low sulfur coal is generally more expensive than high sulfur coal • Scrubbing to reduce sulfur emissions is expensive • Low ash with good reuse potential
Benefits of Wood • Domestic and LOCAL source • Renewable and carbon neutral (?) • Low heavy metal emissions • Extremely low sulfur dioxide emissions • Low ash with good reuse potential • Wood with bark is usually less than 2 % ash and wood itself is less than 1 % • Wyoming coal from Powder River Basin (an example) is 5% • This results is 2-5 times as much ash • While both fly ash (free-$40 per ton) and bottom ash (free to $6 per ton) have markets, their disposal (particularly bottom ash) is usually not a cashflow, it is usually a cost
Problems • Collection • Freight • Storage • Burning
Problems • Collection • Existing concentrated sources already used • Dispersed sources require new technology or different operation of equipment while harvesting • Freight • Storage • Burning
Problems • Collection • Freight • Shipping is one of the highest costs, often 50 miles is quoted as the maximum freight (this is subject to a lot of debate however) • Storage • Burning
Problems • Collection • Freight • Storage • Chips have limited storage life • Bundles have much longer storage but require an additional step in the processing • Other methods? • Burning
Problems • Collection • Freight • Storage • Burning • Wood as a “chunk” is as strange fuel (part is cooking, part is having volatiles produced and part is charcoal all at the same time, therefore it is hard to control) • In most large plants it has to be pulverized • In nearly all cases, moisture of the material reduces harvestable heat. Wood is generally to high moisture without some natural or artificial drying.
Potential Users • Heat • Electric • Co-gen
Conclusions • Biomass for energy is a very viable energy source for the US • There is a large resource out there • As energy prices increase, the economic viability of these fuels is also increasing • However, care needs to be taken not to repeat errors from the 1980’s
1 KWh = 3413 BTU1 therm = 100,000 BTU • 1 kilowatt hour of electricity = 3,413 Btu1 cu. ft. natural gas = 1,008 - 1,034 Btu1 therm gas = 100,000 Btu1 gallon crude oil = 138,095 Btu1 barrel crude oil = 5,800,000 Btu1 gallon gasoline = 125,000 BtuFrom CO Biomass