IGCC: the next generation

The USA is investing in the first of a new generation of coal plants using commercial gasification technology to reduce emissions.

Michael Wadley and William Ruzynski, Excelsior Energy Inc, Minnesota, USA

The Mesaba Energy Project is a demonstration of the next generation of integrated gasification combined cycle (IGCC) plants to produce power from coal. Mesaba 1, with an installed capacity of 531 MW (net), will be located in the Iron Range region of northeastern Minnesota, USA, and will be in service in 2010. Excelsior Energy Inc will build, own, and operate the Mesaba Energy Project. Excelsior is an independent energy development company based in Minnetonka, Minnesota, that has been involved in the development of a gasification project on Minnesota’s Iron Range since 2001. Additional Mesaba units using the same design on the same site or additional sites are contemplated.

Mesaba will accelerate the deployment of advanced clean coal projects and help the industry meet the US Department of Energy’s (DOE’s) aggressive roadmap goals for coal fired power generation with minimized environmental emissions. It aims to demonstrate significant performance, efficiency and emission improvements that would make it the cleanest coal fired power plant in the world.

The project will be located on a site near a taconite mining and processing facility. The Iron Range region was the source of a large portion of the iron ore supporting US steelmaking during World War II. In addition to electricity production, Mesaba may provide additional products including heat and synthetic gas for ongoing taconite production.

Figure 1. ConocoPhillips’ E-Gas Technology for solid fuel gasification
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The project will be based on ConocoPhillips’ E-Gas Technology for solid fuel gasification. The starting point for the project design is the Wabash River coal gasification repowering project, sited at Terre Haute, Indiana, USA.

Wabash was built under the DOE’s Clean Coal Technology Program and it has been in operation since 1995.

Wabash has achieved an impressive across-the-board emissions profile, even compared to alternative technologies being proposed and permitted for new coal fired power projects today. Mesaba is designed to advance this across-the-board performance to achieve criteria pollutant emission levels (SOx, NOx, mercury and particulate matter) equal to or below those now considered to represent lowest achievable emission rates for coal fired generation. What is more, carbon dioxide emissions will be 15 to 20 per cent less than most existing coal power plants.

Mesaba can draw upon the DOE-funded studies of potential Wabash performance upgrades, operational lessons learned from eight years of hands-on operating experience at Wabash and the research and development efforts of the DOE and ConocoPhillips’ gasification team, and as a result will show demonstrable improvement on all environmental and other performance criteria from the Wabash plant. The plant will be designed to achieve more than 15 per cent higher availability than Wabash and further improved thermal efficiency at lower installed unit costs.

Existing coal fired IGCC facilities in the USA have an average heat rate of about 9130 Btu/kWh (for example, Wabash has a rate of 8910 Btu/kWh and Polk power station 9350 Btu/kWh). The Mesaba base case heat rate of 8605 Btu/kWh (HHV basis, Illinois No. 6 coal and base case turbine) reflects a significant improvement in overall cycle efficiency of approximately 500 points.

During the project definition phase, Excelsior will evaluate and determine the commercial viability of the latest generation of combustion turbines, which would further improve heat rate and increase output and utilize a combination of Illinois No. 6 bituminous/coke/PRB (Powder River Basin) sub-bituminous coal for project fuel, resulting an a fuel-flexible plant over its operational lifetime.

Figure 2 – 6. Mesaba’s planned emissions, compared to the three coal-fired power plants in the US EPA’s database that have the lowest permitted emission rate for each specific pollutant. Rates from those three facilities as of 27 September 27 2004 are compared to Mesaba’s targeted rates. Robert Evans, Excelsior Energy Inc.
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The Mesaba Energy Project’s target is to demonstrate emission rates equivalent to the “lowest achievable”, across-the-board reductions in air pollutant emissions relative to traditional coal fired power plants, even comparing Mesaba to the best plant emissions in the nation in each emission category. The US Environmental Protection Agency’s (EPA) RACT/BACT/LAER Clearinghouse database demonstrates that such across-the-board reductions have never been realized in a coal plant of any kind.

From an environmental emissions perspective, the IGCC technology is relatively indifferent to the sulphur content of the fuel, because the sulphur is removed during the gasification process, prior to power generation. The resulting sulphur product from the IGCC facility is in elemental form, suitable for marketable sale for fertilizer production or other applications.

This characteristic has benefits for the fuel cost by accommodating the use of wide variety of possible fuel mixtures throughout the project’s operating lifetime, depending upon the costs of various fuels and transportation modes at the time.

Site locations are being reviewed for their ability to support this fuel flexibility. Sub-bituminous coals from Wyoming and Montana, bituminous coal from Illinois and Indiana, and petroleum coke could be shipped to the site by rail. In addition, the Iron Range region, which has always seen movement of very large volumes of taconite ore and pellets to eastern US locations via shipping on the Great Lakes, also offers options for Illinois or Indiana coals to be shipped by lake vessel to ports on Lake Superior at Duluth and Taconite Harbor, Minnesota. From there, the coal would then be reloaded on rail cars for direct shipment to the site.

Excelsior is currently in the final stages of site selection, considering multiple sites on the Iron Range region. One potential site is located near Hoyt Lakes, St Louis County, Minnesota, and sits on a very large (and now inactive) industrial site that has many strategic advantages. It has rail access; a port on Lake Superior; a dedicated cooling water supply; critical site infrastructure; a large land buffer and, very importantly, widespread local support of its use for an innovative clean-energy technology project. Preliminary site environmental evaluations have been completed and indicate that there are no critical barriers inhibiting successful deployment of the Mesaba Energy Project on this site. Other sites near active taconite processing facilities are also being investigated.

There are two potential sources of raw water for the project. Depending upon the site, there may be large abandoned mine pits on the property that have filled with water. Make up water and/or condenser cooling water can be obtained from these pits. The other possible source would be a pumping station using nearby lakes as reservoirs.

As regards disposal of wastewater, there are two basic options, depending on the site chosen. The first is to discharge wastewater into existing taconite tailings basins. The basins were used for disposal of waste from taconite processing and to supply water for taconite crushing and grinding. Alternatively, a wastewater treatment facility would be built and the effluent from the treatment plant discharged into appropriate surface water.

Permits and export

Generator outlet facilities and necessary network upgrades will be assessed by the Midwest System Operator (MISO), the independent transmission operator for the region.

Transmission plans will include interconnection from the plant site to Forbes substation. Forbes is a major existing facility now interconnected by 500 kV facilities extending to Winnipeg, Canada and in the US to the Twin Cities of Minneapolis and St Paul. In addition to the Iron Range, the Twin Cities is one of the eventual marketplaces for Mesaba output. In order to export power to them, additional work will probably be required to increase transmission capacity between Forbes and the two cities.

Excelsior expects that most, if not all, of the new transmission segments can be accommodated within existing utility rights of way. This will significantly minimize environmental issues that otherwise might arise with greenfield sites and routes.

Legislation in Minnesota

Licensing the Mesaba Energy Project will require acquisition of preconstruction, construction and operating approvals at the federal, state, county, and local government levels. Generally, the first step in obtaining preconstruction permits for the power plant and associated high voltage transmission lines would be to demonstrate their need in a proceeding at the Minnesota Public Utilities Commission. However, in 2003, the Minnesota Legislature enacted a law (Minn. Stat. 216B.1694), which grants the Mesaba Energy Project an exemption from the state regulator’s “certificate of need” process for all present and future generation and transmission infrastructure, and provides eminent domain rights for those facilities. This will greatly expedite transmission siting and construction.

Figure 7. On 30 January 2004 the EPA published proposed limitations for mercury emissions from new generating units. The above facilitates comparison of Mesaba’s targeted emission rate (assuming 90% removal of the mercury from concentrations contained in the “as delivered” fuel analysis). Robert Evans, Excelsior Energy Inc.
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The exemption of need determination allows the Mesaba Energy Project to proceed directly to the permitting and state environmental review processes. Currently, Excelsior is finalizing the scope of engineering and environmental studies required to support preconstruction permit applications for the IGCC power plant and the transmission segments supporting distribution of its output. These studies must, among other things, demonstrate to the Minnesota Environmental Quality Board that the Mesaba Energy Project site and transmission line routes minimize societal impacts.

State support

Over the past years, taconite industry employment on the Iron Range has fallen from a high of nearly 18 000 jobs to less than 4000 jobs today. This, coupled with downturns in the paper and forest products industries, has had an acute and severe adverse effect upon the economy in Northeastern Minnesota and the people of the region. Last year the unemployment rate in St Louis County, Minnesota averaged 5.58 per cent (the labour force averages 109 717). This compares to 4.9 per cent in the state of Minnesota at large.

Over the past year the general trend has been a rise in unemployment in the region. Many of the jobs lost in the region have been in the heavy industrial sector, which indicates that the workforce is suited to the highly skilled industrial jobs that will be created by the Mesaba Energy Project. These numbers indicate a local economy capable of providing necessary personnel for both construction and operation of the project. The Mesaba Energy Project will stimulate the local economy and provide employment opportunities.

Minnesota’s governor and legislature, state development agencies such as Iron Range Resources, and local communities, in addition to Minnesota’s senators and a substantial number of its representatives in Congress, have long been important supporters of the Mesaba Project because it will bring renewed economic vitality to the Iron Range. The project expects to create 1000 local construction jobs over the three year construction period and several hundred direct permanent jobs when commercial operations commence, including additional employment and economic stimulus in surrounding communities.

The Minnesota Legislature adopted enabling legislation for the Mesaba Energy Project that entitles Excelsior to a long-term power purchase agreement for the bulk of its output, as well as the right to be considered for all fossil fuel capacity additions required to meet the projected significant near-term baseload demand growth in Minnesota.

As well as the state legislation that exempts the Mesaba Energy Project from certificate of need proceedings for all generation and transmission infrastructure and grants Excelsior eminent domain rights for project facilities, the site will be designated as a tax free “job zone” under Minnesota law, affording the project a holiday from various state and local taxes for twelve years. Strong, active local support for the Mesaba Energy Project and the employment and economic development stimulus it provides will ensure a timely and successful project implementation.

At the federal level the project has also won support. In October, it was awarded $36 million in development funding from the DOE’s Clean Coal Project Initiative. Mesaba was one of only two IGCC projects nationwide selected for DOE funding in this funding cycle.

Mesaba takes its name, meaning “sleeping giant,” from an Ojibwa Native American legend of the Iron Range. It will awaken coal’s true potential to meet the US’s need for baseload power generation resources, reducing pressure on scarce natural gas resources, and using an abundant domestic natural resource.

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