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by onlinethymes

Environmental Update

Mon, Aug 25th 2008 09:00 am

The doused plans for a new, state-of-the-art ‘clean coal' facility at NRG Energy's Huntley Plant in Tonawanda has been all over the news since the New York Power Authority pulled the plug on the project last month. Reports stated that the reasoning behind NYPA's decision rested on the enormous costs of the project and that the proposed technology was unproven. But what is this unproven technology and why is it so expensive?

The first thing any environmentalist will tell you is that there is no such thing as ‘clean coal.' Burning coal and other fossil fuels to produce energy is an inherently polluting process. The problem is that energy produced from fossil fuels accounts for 86 percent of the world's energy consumption with coal-derived energy consumption at nearly one-third (Energy Information Administration.) Since changing the world's energy source clearly cannot happen overnight, efforts have been made to develop energy-producing technologies that create less pollution and find alternatives to releasing Carbon Dioxide into the atmosphere in an effort to combat global climate change.

NRG Energy's proposal was to build a coal-fueled plant that used the cleanest technology available, integrated gasification combined cycle (IGCC,) and combine it with carbon capture and sequestration (CCS.) According to the Electric Power Research Institute, this combination of technologies does not currently exist at a power plant.

In its IGCC & CCS Background Document, the EPA states that IGCC technology "integrates" the process of gasifying coal with gas turbine and steam power generation which operate as a combined power cycle. The gasified coal fuels the gas turbine and waste heat is then recovered to generate additional steam power. Not only is it a more efficient process, but it also creates significantly less pollutants, uses 35 to 45 percent less water and discharges 30 to 50 percent less solid waste and wastewater than traditional coal-fired plants.

The EPA also states that IGCC offers cost-effective carbon capture capabilities. By adding a shift conversion during the gasification process, carbon dioxide can be separated and captured before combustion yielding a higher concentration of CO2 and requiring a less energy-intensive absorption process than conventional plants.

But cutting-edge technology does not come without problems. IGCC plants are constructed at a premium without adding CCS to the mix. Besides adding to construction and operating costs, CCS has an entire set of issues all its own.

In NRG Energy's proposal, 65 percent of the CO2 from the gasification process would be captured and stored via geologic sequestration. Geologic sequestration (GS) of CO2 involves compressing the gas into liquid form to be injected into deep geologic formations, trapping it underground instead of releasing it into the atmosphere. To be a successful option for mitigating climate change, the CO2 would need to remain underground for hundreds or even thousands of years. How long is just the beginning of the uncertainties

associated with GS, many other questions remain unanswered.

Because of its buoyancy, scientists are uncertain of the likelihood that the CO2 will migrate through discontinuities in the earth and leak through the surface. Not only could surface leakage pose risks to human health, too much leakage would render GS ineffective in averting climate change. Buoyancy also raises questions about the possibility of negative effects to groundwater quality.

Another issue is the shear volume of CO2 that would need to be sequestered. According to the Department of Energy, a 150-megawatt coal-fired plant releases approximately one million tonnes of CO2 into the atmosphere annually. If NRG Energy's 680-megawatt plant sequestered 65 percent of its CO2 emissions as proposed, that would equal nearly three million tonnes annually or 176 million tonnes over a 60-year plant lifetime. Senior MIT research engineer Howard Herzog compares the amount of CO2 that would need to be handled in a day to the amount of oil consumed in a day. That's a huge amount of CO2

being pumped into the ground when we are uncertain of even the local, not to mention regional or global impacts.

NRG Energy's proposal for the 680-megawatt IGCC plant with CCS is certainly on the cutting edge of available ‘clean coal' technology, and that is reflected in its extravagant price tag. The risks and benefits of GS are uncertain, and definitely unproven, but with the time frame involved, how could it ever be ‘proven?' NYPA's decision was based on cost and uncertainty, but what about environmental costs? We know that climate change is happening, and we know why. We can even predict the devastation that continued global warming will bring. But should we take risks when we don't know what the fallout may

be 100 or even 1,000 years from now? Do we collectively pay the higher prices because the benefit of a healthy environment for future generations far outweighs the cost in dollars? These are the questions that underlie NYPA's decision to rescind their support of the proposal. But what are the answers?

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