Woody Biomass Background

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Woody Biomass Background
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Some History

• 1970s energy crisis results in government
  subsidies and research
• 1978 Public Utilities Regulatory Policy Act
  (utilities must buy energy from other producers)
• During 1980s, 6,300 megawatts of new wood fired
  capacity added (from 200 megawatts in late
  1970s)

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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 1990s 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

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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.

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US energy use
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US Energy Use (Scary Numbers)

• About 100 Quads per year (DOE 2000)
• A quad is a quadrillion BTUs
• 100,000,000,000,000,000 BTUs is US use
• 100,000,000,000 MMBTUs

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US Energy Use (Scary Numbers)

• About 100 Quads per year (DOE 2000)
• A quad is a quadrillion BTUs
• 100,000,000,000,000,000 BTUs is US use
• 100,000,000,000 MMBTUs
• 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

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We will not be replacing all energy consumption
with biomass, but it can be part of the picture
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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

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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)

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Outline

1. Benefits of wood
2. Problems
3. Potential users

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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

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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

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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

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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

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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

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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

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Problems

• Collection
• Freight
• Storage
• Burning

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Problems

• Collection
• Existing concentrated sources already used
• Dispersed sources require new technology or
  different operation of equipment while harvesting
• Freight
• Storage
• Burning

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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

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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

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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.

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Potential Users

• Heat
• Electric
• Co-gen

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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 1980s

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• 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