Hydrogen Energy California LLC (HECA) said it switched from a General Electric gasifier technology at its planned power plant in Kern County, Calif., to a technology supplied by Japan’s Mitsubishi Heavy Industries (MHI) because the MHI technology is newer and more efficient.
The company on Oct. 3 filed with the California Energy Commission a series of responses it sent to the Sierra Club, an intervenor in the commission’s ongoing review of a revamped project. A new developer in 2011 took over the project and changed a number of aspects from the concept first filed with the commission in 2009.
One Sierra Club question had to do with the fact that the U.S. Department of Energy selected the HECA project for demonstration and funding under DOE’s Clean Coal Power Initiative (CCPI) Round 3. At that point, the project was proposed with gasification technology and combustion and steam turbine generators developed and manufactured by GE. The project design has since undergone significant design changes and now proposes to use gasification technology and combustion and steam turbine generators developed and manufactured by MHI.
“The MHI technology is a newer design and has features that work to reduce capital costs, reduce operations and maintenance costs, improve efficiency, and improve product availability,” said HECA about why it made the technology change. “All of these factors work to lower the cost of the finished products that Hydrogen Energy California (HECA) will produce.”
The HECA response added: “The 2009 Revised Application for Certification (AFC) was based on an entrained flow, slurry-fed, refractory-lined, quench design featuring two operating 900-cubic-foot reactors with a common spare to facilitate maintenance on feed nozzles, refractory, and other wear items. For comparison, the MHI gasifier is a two-stage, dry feed, entrained flow, membrane wall gasifier that employs a synthesis gas (syngas) cooler for steam production. The membrane wall and feed nozzle design in the MHI configuration is expected to provide a longer run time between shutdowns. A single MHI gasifier is capable of producing 50 percent more syngas at a level of availability comparable to the original configuration—which required three vessels along with their associated structures, appurtenances, piping, and instrumentation. Although the gasifier is larger and more complex, the Project expects to capture economies of scale, reductions in equipment count, and a reduction in the frequency of shutdowns; this would translate into lower costs, higher efficiencies, and lower emissions.”
The MHI gasifier has the theoretical capability to achieve feedstock flexibility similar to that of the previously proposed GE refractory lined gasifier. But operating experience is necessary to determine whether this theoretical capability can be fully realized, HECA noted.
During the gasification process, ash from coal and petroleum coke (petcoke) is melted, and then cooled by a membrane wall in the MHI design, where it vitrifies to form a protective layer. This protective function is a critical design element of all entrained flow gasifiers, and the melting point, viscosity, and other important properties are very dependent on the ash properties of the feedstock. Petcoke has a much different quantity and composition of ash, and demonstration at scale must be incorporated into the experience base of MHI before the full range of feedstock flexibility can be determined and guarantees can be made, HECA pointed out.
The vendor performance guarantees for all of the plant components will be included in the agreements currently under negotiation for engineering, procurement, and construction, and operations and maintenance, HECA noted. The details of these guarantees, once finalized, are very closely held by the equipment manufacturers, because they determine each manufacturer’s competitive position in the markets, it added.
Project targets feedstock mix that MHI will guarantee
HECA said it requested from the technology supplier feedstock flexibilities that would maximize its ability to feed various blends of coals and petcoke from multiple refineries. To date, the maximum performance guarantee the manufacturer has been willing to provide HECA is a 25% petcoke-75% coal blend.
A September “conformity” report that HECA filed with the commission and local authorities noted that the company is proposing an integrated gasification combined cycle (IGCC) polygeneration project located about seven miles west of the city of Bakersfield, and 1.5 miles northwest of the unincorporated community of Tupman, in western Kern County.
The project will gasify a blend of 75% coal and 25% petcoke to produce synthesis gas (syngas). The syngas will be purified to hydrogen-rich fuel, and used to generate a nominal 300 MW of baseload electricity, with CO2 from the project to be used for enhanced oil recovery in the nearby Elk Hills oilfield.
The report said that Western sub-bituminous coal will be supplied from mines in New Mexico and transported by rail, which is somewhat unusual in that this kind of coal is mostly produced in the Powder River Basin of Wyoming and Montana and there are only a few coal producers in New Mexico. They are mostly Peabody Energy (NYSE: BTU) at two strip mines and BHP Billiton at surface and deep mining operations that are currently captive to nearby power plants.
Commercial operation of HECA will start in September 2017, and the construction phase of the project is expected to end in June 2017, the conformity report said.
In September 2011, SCS Energy California acquired 100% ownership of HECA from BP Alternative Energy North America Inc. and Rio Tinto Hydrogen Energy LLC.