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NORTH DAKOTA’S FREEDOM MINE IS
PART OF AMERICA’S ENERGY FUTURE
Domestic mining article by Harold Hough Oct/Nov
2009
Lignite is the forgotten coal. It doesn’t have the high energy
value or the low percentage of impurities of anthracite coal. Nor, does
it have the “coking” ability of bituminous coal, which makes
that coal ideal for steel production. Lignite is usually seen as occupying
the bottom of the coal hierarchy because it is softer, contains about
35% water, and has a lower energy value. Yet, it is an important power
source for America’s electrical grid and a source for the new breed
of synthetic fuels.
Lignite is a major domestic energy source, with about 30 million tons
being mined a year. The lignite reserves of North Dakota alone are estimated
to be 25 billion tons – enough to provide an 833 year supply at the
current rate of mining. That doesn’t include the estimated 325 billion
tons of lignite that is thought to exist in the region, but isn’t
economical with current technology.
The largest lignite mine is the Coteau Properties’ Freedom Mine.
It not only provides 16 million tons of lignite a year to the Basin Electric
Power Cooperative, it also provides lignite to the Great Plains Synfuels
Plant. The mine also boasts an enviable safety record, including two MSHA
Sentinels of Safety Award in the last six years.
The Freedom Mine has an aggressive reclamation operation that has won
several awards for its reclamation program. Approximately 700-1,000 acres
of land are reclaimed each year at the Freedom Mine --the same amount
as the acreage disturbed by mining. Most of the land is returned to cropland
and rangeland; however, the company, worked with government agencies to
design and develop the Harmony Lake Wildlife Management Area. The 45-acre
lake, and 637-acre wildlife area was donated to the state of North Dakota,
and is recreational destination for the local community.
NORTH DAKOTA AND LIGNITE
“There is more appearance of coal today than we have yet seen.
The stratas are 6 feet thick in some instances; the earth has been birnt
in many places, and always appears in stratas on the same level with stratas
of coal.” Journal of Meriwether Lewis, April 29, 1805, Lewis and
Clark Expedition.
Although the Lewis and Clark Expedition discovered lignite in the Dakotas,
it took several decades before it was exploited. Ironically, coal was
being mined in the Dakotas even before the Dakota gold rush. In 1873 several
small mines sprung up along the main routes of transportation in western
North Dakota. By 1900 there were 73 mines operating in North Dakota. Many
of these were small, seasonal mines that removed coal from the face of
the outcrop. They were called wagon mines because area farmers and ranchers
would often bring their own wagons to the site to be filled with coal.
Still, other mines were large operations employing hundreds of men with
underground workings extending for thousands of feet. By the early 1920s,
there were approximately 250 mines operating in the state, with an equal
number of underground and surface strip mines. The advent of the steam
shovel increased the profitability of the surface mines and the last underground
mine closed in 1966.
Today, lignite continues to be mined in open pit operations. The Freedom
Mine works a 13 to 20 foot seam that is between 50 to 150 feet below ground.
That requires moving more than 100 million cubic yards of overburden a
year to get to the coal. As a result, the mine owns a fleet of massive
earth moving equipment like the Bucyrus-Erie Model 2570 walking draglines,
which weigh 13 million pounds each and rival the height of the North Dakota
Capitol.
Although lignite doesn’t have the energy per pound of some coals,
it has many characteristics that make it desirable. Lignite is more accessible
than other types of coal because lignite veins are located relatively
near the surface, eliminating the need for underground excavation in tunnels.
Surface mining also eliminates the risk of methane or carbon monoxide
buildup. As a result, lignite powered electricity is much cheaper than
other power sources. A cost ranking by Global Energy Decisions ranked
four lignite coal power plants in the top 40 low cost power plants in
the US. That’s one reason North Dakota has one of the lowest electrical
energy rates in the nation.
Lignite is also an important part of America’s growing synthetic
fuels industry. Each day the Great Plains Synfuels Plant converts approximately
18,000 tons of lignite coal into an average 145 million cubic feet of
synthetic natural gas for home heating and electricity generation. It
also produces several agricultural and chemical byproducts like naphtha,
which is used in the production of gasoline and benzene. Carbon dioxide,
which is produced during the process, is piped 205 miles to Saskatchewan,
Canada where it is used to enhance oil recovery capabilities in partially
depleted oil fields. This not only prolongs the life of the oil field
and allows more oil to be recovered than by drilling alone, it sequesters
the CO2.
Not only is lignite used for energy and synthetic fuels, it is also a
source for used to produce fertilizer products (anhydrous ammonia &
ammonium sulfate). Some is even used for oil well drilling mud, since
lignite has a high percentage of humic acid, which is a useful drilling
mud thinner.
Ironically, even though bituminous coal is used in steel production as
coke, lignite has found a use as an additive to foundry sand during casting
operations. The humic acid and carbon in lignite tend to absorb volatile
organic compounds created during the process. It also makes sand molds
more effective and less expensive.
Although lignite hasn’t received the attention of other coals, it
has proven to be a reliable and inexpensive source of energy for over
a century. Given the massive reserves in the upper Great Plains of the
United States, it’s likely to be a source of energy for many centuries
to come.
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