The gasification man cometh

The acquisition by GE Energy of ChevronTexaco’s gasification technology has raised the prospect of IGCC power production finally becoming a viable alternative technology, able to use low cost coal fuel and achieve acceptable emission levels

Nigel Blackaby, Features Editor

In June of this year, GE Energy announced the completion of its deal to acquire the assets of ChevronTexaco’s gasification technology business and in doing so, combined the world’s two leading participants in the field of Integrated Gasification Combined Cycle (IGCC) power plants. The implication of a marriage between the main licenser of gasification processes and the firm responsible for 65 per cent of the power islands in operating IGCC plants, is that customers may at last have the option of a fully integrated and optimized solution at a cost comparable to that ofconventional pulverized coal plants.

Essentially, IGCC power plants take a low cost solid fuel like coal and gasify it into a low-BTU gas, from which are removed the particulate and sulphur matter. This gas is used as a primary fuel for the gas turbine in a combined cycle system. IGCC systems therefore offer significant environmental benefits compared to more traditional pulverized coal power plants.

The first of the three stages that make up an IGCC system is the gasifier island. This prepares the fuel through partial oxidization in which an air separation unit (ASU) adds oxygen to the process. The second is an acid gas system that cleans up the partially oxidized gas. The resulting synthetic gas (syngas), composed mainly of carbon monoxide and hydrogen, is then fed into the third stage, the power island (the combined cycle system).

A typical Integrated Gasification Combined Cycle process flow
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Depending on the level of integration of the various processes, IGCC may achieve 40-45 per cent efficiency, greater than 99 per cent sulphur dioxide (SO2) removal and nitrous oxide (NOx) below 50 ppm.

Limited success

Despite this type of clean coal technology being able to produce environmental performance close to that achieved by natural gas, the basic technology has existed for decades without making a major commercial breakthrough. ChevronTexaco has licensed 63 gasification units worldwide although there are perhaps only four true coal fired IGCC plants currently operating on a commercial basis. The main problem has been that the technology has not been cost competitive compared with mainstream alternatives. In addition, the construction of an IGCC plant has involved too many parties, each concerned with a separate aspect of the process. Until now, none of these entities had enough incentive to properly integrate the process.

Clean coal market

So why has GE decided that now is the time to invest in this technology? “We saw the convergence of a number of market forces in the US, in particular a significant interest in coal over the rest of this decade due to high and volatile gas prices and a desire by our customers to have a fuel diversity mix in their power generation,” explains Ed Lowe, general manager of gasification technology and product line management at GE Energy. “By being able to acquire this technology and offer a cleaner coal IGCC solution, we were giving our customers another option to burn coal,” says Lowe.

Although GE’s focus for IGCC is the US market in the first instance, there is a recognition that this technology has worldwide applications. The existing installations are evenly divided between the US, Europe and Asia. GE plans to push gasification technology on a worldwide basis, not just in IGCC applications but also in the chemical industry, where the syngas that is produced can be used in the manufacture of chemicals, such as ammonia and in hydrogen production. GE will not be drawn on any projections for market size but Lowe says, “We see this as a growing market in the US and worldwide because of the cleaner coal option that it provides.”

Commercialization challenge

The challenge ahead is for GE to bring to market a reliable and cost effective IGCC solution. IGCC plants are expensive to build. It is generally accepted that the capital cost of IGCC is higher than pulverized coal by around 20 per cent. By bringing the technology in-house, GE intends to produce significant savings through more efficient integration and the introduction of a complete IGCC package. “Our goal in this design process is to achieve parity between the costs of conventional coal and IGCC power production,” explains Lowe.

In addition, reliability, availability and maintainability of an IGCC system is less than that of equivalent pulverized coal systems. By modifying and refining the design and in particular looking at the interface issues, GE intends to address these problems and at the same time take the technology forward and improve the overall efficiency.

Tampa Electric Company’s 250 MW Polk IGCC plant in Florida
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A third drawback is that currently the type of overall plant availability warranties that owners expect are not available for IGCC systems because of the multitude of suppliers involved ” the technology licenser, design engineering firm, air separation and acid gas clean-up equipment supplier, power island supplier and constructor. “If the plant doesn’t perform up to expectations it is essentially the owner’s issue, because they did the integration,” says Lowe. “GE plans to offer a one-point solution for an IGCC power plant, taking responsibility from the coal pile to putting electrons on the busbar.”

In pursuance of this goal, GE has established an alliance with Bechtel Corporation to develop a standard commercial IGCC offering, bringing in Bechtel’s engineering, procurement and construction expertise. GE has worked with Bechtel on numerous IGCC projects, including the 100 MW Cool Water plant in California, a demonstration project completed in 1984 using ChevronTexaco gasification technology and the Tampa Electric Company’s 250 MW Polk Power Station in Florida, which began operation in 1996.

GE is confident about the future for IGCC. “We believe that this acquisition has addressed some of the gaps that have been there for commercializing this type of technology rapidly,” says Lowe.

DOE support

The move by GE to acquire ChevronTexaco’s gasification technology coincides with a renewed interest in a wide variety of clean coal technologies in the US. The Bush administration has pledged to commit $2 billion over ten years to advance clean coal technology in the knowledge that coal is likely to remain one of the lowest-cost fuel options available to the electric power industry in the foreseeable future. The Clean Coal Initiative is providing government co-finance for six new coal technology projects, four of which are currently in the design phase while two projects are still in the pre-award phase. They aim to make full-scale demonstration projects to ensure proof-of-operation prior to commercialization.

Among the projects are two utilising IGCC technology, which the US Department of Energy (DOE) has referred to as, “Promising dramatically increased efficiency and reliability, improved environmental performance, reduced capital and operating costs, and flexibility to process both high and low rank coals.” In October, the DOE announced it would contribute $235 million towards the development of a $557 million IGCC plant in partnership with Southern Company. The 285 MW plant will be located at the Orlando Utilities Commission’s Stanton Energy Center and will use installed advanced emission controls, making it one of the cleanest, most energy-efficient coal power plants in the world.

The technology to be used by Southern Company and Orlando Utilities is based on the transport gasifier that Southern Company, DOE and others have been developing at the Power Systems Development Facility near Wilsonville, Alabama for more than a decade. It is unique among coal gasification technologies in that it is cost-effective when handling low rank coal, as well as coals with high moisture or high ash content. These coals make up half the proven US and worldwide reserves.

Perhaps an even more significant development is the decision by American Electric Power (AEP) to build at least one commercial-scale base load IGCC plant of up to 1000 MW. AEP has said that construction costs for such a plant are as low as $1300 per installed kW. Both Southern Company and AEP target 2010 for the commercial operation of their plants.

GE has set itself an aggressive target for the commercialization of its IGCC technology, according to Lowe: “Before the end of this year GE expects to announce that it has reached agreement with a customer for the delivery of a large (600 MW) standard IGCC plant. Commercial operation will be in the 2008-2009 timeframe.” The customer, Cinergy Corporation, has agreed to work with the GE-Bechtel alliance on a feasibility study for an IGCC plant on this scale.

Future expectations

As a commercial proposition, IGCC has promised much over the last 20 years but in reality has failed to emerge from its demonstration phase to any significant degree. However conditions now do seem to be favourable for the coal fuelled IGCC sector. This is particularly so in the USA and in other countries that are imposing tighter environmental emissions regulations and yet have access to plentiful coal stocks.

If GE Energy can bring the costs of IGCC into line with traditional pulverized coal plants, tackle the integration and reliability issues through a standardized IGCC design, and supply the equipment with the necessary warranties, it may be on to a winner.

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