June 15, 2007

Kimberlina: A zero-emissions demonstration plant

Keith Pronske, Clean Energy Systems Inc.

Commercialization: The final step

With the successful conclusion of the CEC program, sufficient experience and confidence has been gained to justify contracts for modest-sized (20 to 70 MW_e) first-generation plants using present-day steam turbine technology. These projects fall into two categories: natural gas–fueled plants located where government incentives or CO₂ credits are available, and coal or coke-fueled plants whose CO₂ and (possibly) hydrogen outputs could be marketed separately or bundled with ultra-low-emissions power. Two existing projects in the first category are described below.

The SEQ-1 Project in the Netherlands will use a modified CES process. A CES combustor operating at modest pressure (~500 psia) and fueled by natural gas recovered from a "depleted" field will create steam in a compact heat-recovery steam generator (HRSG) that will drive conventional steam turbines. This 50-MW_e (nominal) power plant will pump the captured and separated CO₂ into the same field to enhance gas recovery.

Three unique factors favor the commercial viability of this project:

• The Dutch government has legislation in place that subsidizes climate-neutral electricity sources (including zero-emissions power plants) to the same extent as wind, solar, and biomass power.
• The geology of the gas field has been determined suitable for enhanced gas recovery.
• Dutch developers, working with CES, have brought together the necessary entities to evaluate the project and reach a consensus about its viability. A consortium to develop the project has been formed; among its members are ONS, a Dutch municipal utility, and a major European oil and gas company.

For more information on this project, visit www.seqnederland.nl.

The Zero Emissions Norwegian Gas (ZENG) Project is being jointly developed by Lyse Energi AS, Nebb Engineering AS, Procom Venture AS, and CO2-Norway. It is supported by Norway's Oil and Energy Department, Lyse Energi, and the U.S. DOE. The goal of this program is to develop and demonstrate "near-commercial" technology for zero-emissions power generation using Norwegian natural gas to fuel CES's oxy-combustor. Zero-emissions power plants are of particular interest in Norway because its government imposes high taxes on CO₂ emissions.

The ZENG project (Figure 7) is a multiphase effort. Phase 1, completed in July 2004, produced a concept and feasibility study. Phase 2, completed in late 2005, focused on preengineering and qualification. Subsequent phases will entail construction of a 50-MW_e demonstration power plant near Stavanger, Norway, that could be commissioned as soon as 2009. Later, a high-efficiency, 200-MW_e zero-emissions power plant would be built at a Norwegian location to be determined. For more information on this project, visit www.zeng.no.

7. Carbon tax shelter. An artist's rendering of the 50-MW zero-emissions demonstration plant to be built as part of Norway's ZENG project. Source: Clean Energy Systems Inc.

CES will also work to make the oxy-combustor compatible with solid fuels. It expects the first generation of plants of this type to have a capacity of about 70 MW_e. At their front end will be gasifiers able to turn low-cost coal or coke feedstock into syngas fuel for the CES combustor. These plants will use the indirect cycle proposed for the SEQ-1 project: the combustor's output raises steam in a compact HRSG that is used to drive conventional steam turbines. Early plants will use several of the 50-MW_t syngas combustors that were demonstrated successfully at the Kimberlina facility. Later plants will leverage lessons to be learned about the combustor and controlling it as part of the SEQ-1 project.

Ideally, a solid-fueled oxy-combustor plant would be sited where there is a local use for the CO₂ by-product (enhanced oil or gas recovery, for example) and where air-quality rules are particularly stringent. An optional feature of the CES process involves separating hydrogen from the syngas stream and using the remaining HDS to fuel the combustor. In these cases, the separated (and very valuable) hydrogen by-product stream could be delivered to local users such as refineries or heavy-fuel upgraders, or injected into a hydrogen pipeline.

Watch out, IGCC

In January 2007, CES announced that it is seeking funding to build the nation's first natural gas–fueled zero-emissions power plant, a 50-MW facility to be sited in California. So far, Southern California Gas Co. has committed to support development of the technology. CES is also seeking funding for the proposed plant from the U.S. DOE and the CEC.

This project, and the ones described earlier, will set the stage for second-generation plants that will use intermediate-pressure gas turbines and other technologies to enable higher-efficiency, low-cost power generation from coal—with CO₂ capture. Near-term plants (available in about five years) would modify existing turbines and other components. Longer-term plants (available in about 10 years) would use advanced technologies such as the high-temperature turbines being developed by Siemens Power Generation with its September 2005 NETL grant.

The second-generation plants would exploit future advances in air separation as well as synergies among the air separation unit, the gasifier, and the power island. By virtue of their high cycle efficiencies and low electricity production costs, oxy-combustor plants look to be a serious cost competitor to other methods of converting coal to electricity with CO₂ capture—most notably, integrated gasification combined-cycle (IGCC) plants.

—Keith Pronske is president & CEO of Clean Energy Systems Inc. He can be reached at klpronske@cleanenergysystems.com