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)

• 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

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

1. Benefits of wood

2. Problems

3. 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