Basin Electric sees wind power as key part of Stepping up to the plate
multi-pronged strategy to reduce greenhouse gases
Stepping up to the plate
By Stephen Thompson,
Assistant Editor
or Basin
Electric
Power
Cooperative,
wind power is
just one of many technologies
being explored to reduce the
co-op’s carbon footprint.
Basin Electric, a generation
and transmission utility co-op
based in Bismarck, N.D., is
pursuing an aggressive effort
on many fronts to meet
future demands for electric
power while reducing
emissions of CO2.
With the U.S. government
getting serious about
reducing carbon emissions,
the cooperative has decided
to try to get out ahead of the
curve. “We recognize that
carbon is an issue, and that
we need to move forward on
it,” says Floyd Robb, vice
president for communications
and marketing support. At
Basin’s 2005 annual meeting,
members passed a resolution calling for a full 10 percent of
their power demands to be met by renewable, or otherwise
“green,” sources by 2010.
A study on the issue by the Electric Power Research
Institute (EPRI) offers no “silver bullets,” says Robb. “The
only way to meet expected requirements is to use a whole range of methods.” The
cooperative has stepped up to
the plate, participating in
projects that include carbon
sequestration, waste-heat
recovery and coal gasification,
as well as wind generation.
“We believe we’re on the
cutting edge,” he says.
Basin Electric currently has
a total wind generating
capacity of 136 megawatts, but
recently launched an effort to
add up to another 300
megawatts-worth of wind
power.
Storing wind-generated
power
The co-op is making
progress on an even more
futuristic goal: a way to store
and use wind power generated
during periods of low demand.
Basin’s wind power is
currently generated by a mix
of turbines owned by the coop
and other turbines owned
by independent wind
developers. The new turbines
will be wholly owned by Basin
Electric, with the project scheduled for construction in three
stages.
The first 99 megawatts will be generated by turbines
going up near Minot, N.D. Sites for the second stage are still
being explored, while the third stage is still in the initial
planning phase. Utility-scale wind turbines currently available
each have a capacity of 1.5 megawatts; so producing 99
megawatts requires a wind farm of at least 66 of the immense
structures.
Projected cost of each of the first two stages is between
$200 and $210 million, to be financed through loans
guaranteed by USDA Rural Development.
The problem with wind generation, of course, is that the
wind doesn’t always blow when you need power, and it often
blows when you don’t need it. There is currently no feasible
way to store electricity generated during low-demand
periods, but Basin Electric has invested $2 million to explore
a practical alternative, as part of the wind-to-hydrogen
consortium of cooperatives and other institutions.
At a site owned by North Dakota State University near
Minot, N.D, excess power from nearby Basin Electric wind
turbines is being used to generate hydrogen gas. The power
is run at low voltage through an electrolyzer, which uses
electric current to break water molecules apart into hydrogen
and oxygen. The hydrogen is stored under pressure and is
used to operate vehicles configured to burn the gas in their
engines.
The advantage of hydrogen as a fuel is that it produces
only water when burned, offering a completely non-polluting
way to power vehicles. At the moment, it’s one of the few
ways to store non-peak energy.
The electrolyzer is hooked up to the power grid, says
Robb, but power use is controlled so that only the amount
generated by the wind is used to produce gas. At the
moment, the co-op fuels three “flex-fuel” pickup trucks with
hydrogen. Gas from the project is also used to run a tractor
owned by the university in Fargo.
“You can put your nose right next to the exhaust pipe and
smell nothing,” says Robb.
Capturing unused heat
Another way to reduce carbon emissions is to capture
unused heat and use it to generate power. That’s the goal of
another Basin Electric demonstration project on the
Northern Border Pipeline, which transports natural gas from
Canada through Montana and the Dakotas to the Chicago
area.
Gas pipelines require compressor stations about every 80
miles, powered by gas turbines. The turbines generate a great
deal of waste heat, which is usually exhausted into the
atmosphere.
The project uses a thermal oil to absorb exhaust heat,
which is routed to a heat exchanger where it boils liquid
pentane. The heated pentane gas is used to drive a turbinepowered
generator, which feeds the electricity to nearby
power lines. The spent pentane gas is condensed and fed
back into the heat exchanger in a closed loop.
The program is run by Ormat Technologies under
agreement with Basin Electric, which purchases the power. It
currently has energy-recovery units on four pumping
stations, each one of which recovers about 5 megawatts of
energy — a not-inconsiderable amount. “It’s the closest thing
to free energy you can get,” says Robb. The only drawback is
that to be economically feasible, the station has to be within a
reasonable distance of power-transmission lines. Four more
units are planned.
Most of the cooperative’s base-load generating capacity is
fired by coal — a fuel that faces increasing opposition from
environmentalists, as well from as citizens leery of the impact
of coal burning on local air quality.
Coal-fired generation plants usually use bituminous coal as
fuel. Low-quality lignite, or “brown,” coal is abundant and
inexpensive in North Dakota. But it has several drawbacks: its
combustion produces even more CO2 and pollutants than
bituminous coal, and due to its low energy content, it’s not
economical to transport.
The co-op uses innovative technology to develop lignite’s
potential while minimizing its environmental impact. At the
Great Plains Synfuel plant in Beulah, N.D., operated by
Basin Electric subsidiary Dakota Gasification Co., brown coal
is used to make natural gas, which burns much more cleanly
and is more economical to transport.
Pumping CO2 into oilfields
Under a demonstration project, the CO2 produced by the
synthesizing process is purchased by two Canadian oil firms:
EnCana and Apache Oil. It is piped 205 miles, across the
border into Saskatchewan, where it is injected deep into two
oil fields that are far past their peak production.
The gas forces otherwise unrecoverable petroleum to the
surface. EnCana says that it hopes to extend the life of its oil
field by as much as 25 years, and pull 135 million additional
barrels of oil from it.
The project is the largest carbon sequestration effort in
the world, and is already responsible for storing 10 million
tons of the CO2. The project is being expanded to store 3
million tons of CO2 each year.
Initial data show that the carbon dioxide is staying where
it’s put, making a tangible contribution to the effort to reduce
greenhouse gas emissions, as well as increasing domestic
energy supplies, Robb says. The success of the project has
encouraged the cooperative to move on to the next step:
looking for ways to remove CO2 from the flue emissions of
conventional coal-fired generation plants.
Basin Electric is currently evaluating proposals from six
vendors to build a demonstration flue-gas carbon
sequestration project. A decision is expected in December.
Robb proudly asserts that Basin Electric is the only utility
seeking to remove carbon dioxide from flue-gas. “Other
utilities talk about it,” he says. “We’re actually doing it.”
