New coal plant equal to 2,000+ wind turbines | Face the State

New coal plant equal to 2,000+ wind turbines
August 13, 2009
By Face The State

Face The State Staff Report

As the Comanche unit 3 coal plant near Pueblo is scheduled to start commercial operation this fall, utilities are also seeking ways to comply with a 2004 ballot measure that requires 20 percent of the state's electricity to come from "renewable" sources. A Face The State analysis explores the relative power of Comanche versus two large wind and solar projects.

Comanche 3, under constructionaflcio/Flickr

In 2004, Colorado voters approved a statewide renewable energy requirement that mandates top utility companies to provide an increasing percentage of their retail electricity sales from renewable sources. Xcel Energy, the state's largest utility, already gets 10 percent of its power from renewable sources and must reach 20 percent by 2020. Meanwhile, Xcel began constructing the new coal-fired electric generating unit in January of 2006. It was Xcel's first new coal plant in nearly 30 years, and will likely be the company's last in Colorado. When the Comanche 3 unit is complete, the site will provide enough electricity for about one third of Colorado’s communities. The plant is also designed to serve as 24-hour backup to less consistent renewable sources.

Environmentalists have come out strong against Comanche 3's construction. WildEarth Guardians has filed a lawsuit in U.S. District Court, asking the judge to order Xcel to stop construction on the Comanche 3 unit. They argue that coal-fired plants produce unacceptable levels of greenhouse gases, endangering the environment.

WildEarth's objections and those of other environmental groups aren't likely to stop Comanche 3 from coming online. But what would it take in green energy terms to replace its output with wind or solar power?

Democrat Gov. Bill Ritter has made his "new energy economy" a policy centerpiece since taking office in 2007. He praised SunEdison for building a solar plant in Alamosa and BP America for constructing a wind farm in Weld County. These projects have taken advantage of generous government subsidies, and feed into the state's grid to help Xcel and other utilities meet their Constitutional mandate.

While solar and wind power are cleaner, they are not cheap and demand a larger geographic footprint than more traditional sources and other alternatives like nuclear. Face The State's analysis shows how the PV solar plant in Alamosa and the Cedar Creek wind farm in Weld County stack up to the the energy production of the Comanche 3 coal plant.

Comanche 3 is expected to generate 750 Megawatts of power at peak output (a Mw is a unit of power representing 1 million watts.) A standard light bulb is 100 watts, while a hair dryer or toaster demand around 1,000 watts. To generate as much power as the 750Mw Comanche plant, SunEdison would need 92 plants like the one in Alamosa operating constantly in prime conditions - with 24 hours of sunlight every day. The plant of course won't operate at night, and due to the earth's rotation around the sun produces less in the winter. Put another way, SunEdison expects to produce 17,000 Killowatt hours from the project per year, a Kw hour being 1,000 watts delivered to a retail user for 1 hour. Comparatively, Comanche 3 will produce energy 24 hours a day, and up to 18,000KwHr in one day, more than the expected yearly output of the SunEdison solar plant. In order for SunEdison to match the maximum output of Comanche 3, it would need to install 386 solar plants covering 30,720 acres, or 48 square miles.

Like the sun, wind has varying degrees of intensity. To compensate for this, industry standards dictate that it would take three wind farms spread out around the state to ensure continuous energy production. To match Comanche 3's output, the consortium behind the farm would need to more than double the size of the current Cedar Creek installation and build two more just like it in other parts of the state. That would total 2,051 wind turbines operating on 240,000 acres, or 375 square miles.

To provide constant output to match retail demand, each watt of energy produced by renewable resources needs to be backed up by a secondary source, like coal or natural gas. Comanche 3 is designed to meet this backup need as Xcel takes older plants offline and replaces these sources in part with renewables.

The numbers:

Comanche Unit 3 coal power plant - Xcel Energy, rural electric co-ops
Maximum output: 750Mw
Cost: $1.3 billion
Location: near Pueblo
Cost per Mw: $1.73 million

Photovoltaic Power Plant - SunEdison
Maximum output: 8.2 Mw
Cost: $60 million
Acreage: 80 acres
Location: Alamosa
Cost per Mw: $7.3 million

Cedar Creek wind farm
Joint venture between the investment firm Babcock & Brown and BP America
Maximum output: 300.5 Mw
Number of turbines: 274
Cost: $480 million
Acreage: 32,000 acres
Location: North-central Weld County, 8 miles east of Grover
Cost per Mw: $1.6 million