Coal gasification plant – in depth article from a surprising source

USAToday has the reputation of producing lightweight content for an audience that is generally just interested in keeping up with the headlines, often while traveling.

I was pleasantly surprised a couple of days ago to find a well researched story titled Tech could reduce coal facilities’ emissions about the potential and the challenges facing a Duke Energy coal gasification plant that is proposed for Edwardsport Ind.

The projected cost for the 630 MWe facility is $2 billion – a bit more than $3100 per kilowatt of capacity. That is quite a bit higher than many people expect for coal fired power generation and is within the range of estimates for new nuclear power plant capacity.

The technology that will be used is called IGCC – Integrated Gasification Combined Cycle. Instead of using pulverized coal in a boiler to produce steam, the input coal goes through a process to turn it into a synthetic gas that can be burned in a combustion gas turbine. Since the output temperature of combustion gas turbines is high enough to produce good quality steam, modern, high efficiency plants use a combined cycle that adds a steam boiler and turbine to achieve an over all thermal efficiency of nearly 60%.

IGCC is not “new” technology; there are two units currently operating that produce about 1/3 as much power as the proposed new plant. Each of the two has been operating for more than 10 years. There have been no follow-ons to those plants put into operation in the period since they were built; I suspect that the industry has been closely watching them to see how they operated and how much they cost to build and maintain.

When I lived in the Tampa Bay area in the early to mid 1990s I served in the Naval Reserves with two people who were involved in the contracting and financing for the unit in Polk County owned by Tampa Electric Co. The challenges of building one of the first of a kind plants made for some very long days for my reserve colleagues. One of the major challenges as described by my friends was that he felt like he was not just building a power plant, but two chemical plants as well. One of the plants was the gasification unit on the front end of the cycle and the other was the exhaust gas treatment on the back end. Unfortunately, I have lost touch with both of them – I really want to find some good sources of actual operating experience.

Discover Magazine included a rather glowing description of the plant in an article published in December of 2006 titled Can Coal Come Clean?, but at least the second half of the article described at least one of the dirty secrets of “clean coal” – mountain top removal.

While reading the USAToday article, I found it very interesting to see the source of some of the strong support given to the project. Here is a quote from the article that describes that source:

“It’s a technology that has the ability to take air pollution out of the debate over coal,” says John Thompson, director of the Coal Transition Program at the Clean Air Task Force, a Boston-based environmental group that supports the plant. “The day that plant opens, the 500 or so coal plants in the U.S. are obsolete.”

I have been having some email conversations with a member of the Clean Air Task Force and hope to have the chance to interview him for an upcoming episode of The Atomic Show Podcast. It will be interesting to find out why there is such strong support for the IGCC concept.

Once the coal has been gasified, the expectation is that the exhaust gases will be easier to handle for the purposes of capturing and sequestering the CO2. This assumption begs a question in my mind. If it is relatively easy to capture the CO2 from an IGCC, why wouldn’t we start working to prove that assumption by capturing the CO2 from at least several of the existing GTCC (gas turbine combined cycle) plants that use natural gas as their heat source?

It may not be so easy – after all, the exhaust of a conventional gas turbine is probably less than 15% CO2; most of the rest is nitrogen and oxygen that would have to be separated from the CO2 to reduce the already enormous volume of gas that will have to be compressed and pumped underground. That separation process for the large volumes of gas produced will be quite a chemical factory that will have to be followed by a compression system and a pipeline unless the plants happen to be located in just the right geographic area for access to underground storage. The IGCC technology in use for the Polk County plant – and presumably the proposed Edwardsport plant – apparently use pure oxygen instead of atmospheric air.

Surprisingly enough, no one interviewed for the article thought to mention that nuclear plants have lower fuel costs than coal, do not need to sequester any gases, and can be built for about the same cost as a coal plant. Of course, the fact that the proposed plant is apparently eligible for $460 million in direct subsidies might have something to do with the decision to move forward. Those will reduce the cost per kilowatt of capacity back down to about $2400.