Sunday, May 25, 2008

Can Coal Save Us?

Some people have suggested that by shifting our power generation to coal based and using CTL (coal to liquid) technology that we can replace a substantial amount of our oil usage with a local resource (coal). The question is then why put the effort to switch to coal when it is ultimately a limited resource and a substantially dirty one at that. If we are going to transition away from oil why not put that effort into long term renewable sources?

Lets look at the potential that coal may or may not hold....

From EIA (Energy Information Administration)
Annually, EIA reports remaining tons of coal in the demonstrated reserve base (DRB), which is comprised of coal resources that have been identified to specified levels of accuracy and may support economic mining under current technologies. As of January 1, 2007, the DRB was estimated to contain 491 billion short tons and recoverable reserve base to contain 264 billion short tons.

There are four major ranks of coal in the U.S. classification scheme. In the United States, coal rank is classified according to its heating value, its fixed carbon and volatile matter content, and, to some extent, its caking properties during combustion. The coal ranks from highest to lowest in heating value are:

  • anthracite (53%)
  • bituminous(37%)
  • sub-bituminous (9%)
  • lignite (1.5%)

Of the four ranks, bituminous coal accounts for over half (53 percent) of the DRB. Bituminous coal is concentrated primarily east of the Mississippi River, with the greatest amounts in Illinois, Kentucky, and West Virginia.

All sub-bituminous coal (37 percent of the DRB) is west of the Mississippi River. Most sub-bituminous coal is in Montana and Wyoming.

Lignite, the lowest-rank coal, accounts for about 9 percent of the DRB. Lignite is found mostly in Montana, Texas, and North Dakota.

Anthracite, the highest-rank coal, makes up only 1.5 percent of the DRB. Anthracite is concentrated almost entirely in northeastern Pennsylvania.

The price of coal varies widely depending on the state that it is being purchased in (states that are coal producers tend to pay substantially less for the coal that is mined within the state). price also varies widely according to the quality/type of coal being bought

Averaged 2006 US Coal Prices ($/Short Ton)

$39.92 Bituminous

$9.95 Sub-bituminous

$14.00 Lignite

$43.61 Anthracite

How does US coal consumption compare to US petroleum (all oil products) consumption?

the annual consumption of coal in 2007 was 1,128,836,000 short tons. Annual consumption growth from 1973 to 2007 averages 2%.

the annual consumption of petroleum in 2007 was 7,554,000,000 barrels (7.5 billion). Annual consumption growth from 1973 to 2007 averages 1%.

In order to make these two energy sources comparable we will look at the energy supplied (BTU's, a unit of energy) by source ( data from EIA)

in 2006 the US consumed 2.26 Quadrillion (1015) Btu of coal and 43.8 Quadrillion (1015) Btu of oil ( assuming an average of 5,800,000 BTU/barrel).

These figures show that the US uses approximately 19 times more oil energy the coal energy

How much Coal does the US have and how much oil can we replace?

the US has 264,000,000,000 (billion) short tons of coal in proven reserves. At out current rate of consumption (1.1 billion short tons) and assuming our current rate of growth in consumption (2%) remains constant then we have an estimated 260 year supply of coal. Well that sounds like a substantial resource, so what happens if we replace some of our oil consumption with coal?

Per EIA 69% of US oil consumption is for transportation, so lets assume that we replace the non-transportation oil consumption with coal (30%). 30% of current oil consumption(43.8 quadrillion BTU) in BTU's is 13 quadrillion BTU. Assuming coal averages 2.2 million BTU/ton (per EIA) then in order to replace all non-transportation oil use at 2007 consumption rates would require an additional 20,000,000,000 (billion) tons per year. that's about 20 times our current coal consumption

If we replace the non-transportation oil consumption with coal and assume the same average energy consumption growth rate for coal as above (2%) then current proven coal reserves would last about 120 years.

if we maintain our current rate of coal consumption and do not increase out utilization of coal outside of our average growth rate current proven reserves would last about 250 years

What does it all mean?
The US holds about 25% of the world reserves of coal. We have the capacity to replace a significant amount of oil usage with coal but are the potentially substantial costs worth it? Coal is of vital important to the steel industry and substantial utilization of coal could have negative impacts on the cost and availability of steel on the open market. Modern day construction is highly depended on steel and there is no ready alternative.
Coal mining is highly disruptive to the environment and is often opposed by surrounding communities. Coal combustion produces about 2.7 tons of CO2 for every ton of coal burned. Given the potential concerns about human driven climate change does it make sense to increase coal consumption?
Coal combustion is also known as the major source of radioactive release into the environment

Oak Ridge National Laboratory(Coal Combustion: Nuclear Resource or Danger)

"Using these data, the releases of radioactive materials per typical plant can be calculated for any year. For the year 1982, assuming coal contains uranium and thorium concentrations of 1.3 ppm and 3.2 ppm, respectively, each typical plant released 5.2 tons of uranium (containing 74 pounds of uranium-235) and 12.8 tons of thorium that year. Total U.S. releases in 1982 (from 154 typical plants) amounted to 801 tons of uranium (containing 11,371 pounds of uranium-235) and 1971 tons of thorium. These figures account for only 74% of releases from combustion of coal from all sources. Releases in 1982 from worldwide combustion of 2800 million tons of coal totaled 3640 tons of uranium (containing 51,700 pounds of uranium-235) and 8960 tons of thorium."

Everyone must come to their own conclusion, I hope you have found this information useful and enlightening. Please remember that the scenarios described above are based on specific assumptions. If you change the assumptions of the scenarios, then the results are likely to change substantially.

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