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Humboldt Bay Generating Station
Humboldt Bay is home to a power plant on the forefront of energy technology. The Humboldt Bay Power Plant, owned and managed by Pacific Gas and Electric Company (PG&E), has adopted some of the newest technology available in the natural gas production of electricity. Sitting in the heart of Humboldt Bay, PG&E was influenced by the Eco-friendliness of the Eureka and Arcata areas to invest in a more efficient technology to produce energy through natural gas.
Powering Humboldt Bay
The Humboldt Bay Power Plant was originally producing electricity by running a steam turbine power plant fueled by biomass, which consisted of lumber mill and logging waste. The plant than began producing supplemental energy in 1947 by salvaging a Russian tanker, used to produce electrical energy using steam, and beaching it so that it could be connected to the electrical grid . Both plants provided power for the Humboldt Bay area for about 54 years, until their decommissioning.
After their decommissioning the plant constructed a nuclear facility that could produce 56 megawatts of electricity. In 1976 the plant closed for retrofitting, but because of new safety standards within nuclear energy production it never reopened. The nuclear plant is estimated to be completely decommissioned by December 31, 2015 .
After decommissioning the biomass and nuclear generators, the Humboldt Bay Power Plant needed a new fuel source. Instead of building a new biomass generator or switching to coal, the decision was made to install a natural gas pipeline and power Humboldt Bay with two natural gas-fired generators. Natural gas has several advantages that make it a logical choice for powering Humboldt Bay, specifically:
- Low production costs
- Stable national supplies and energy security
- Low transportation costs once pipelines are installed
- Fuel versatility and flexibility
- Reduced environmental impact and emissions compared to biomass or coal
The natural-gas power plant used two steam turbine boiler plants, together supplying 107MW to Humboldt Bay. In order to maintain peak efficiency, turbines must be operating very near to maximum capacity. However, energy demands throughout the region fluctuate greatly throughout the year and individual days. In order to keep the power plant running at maximum efficiency during non-peak hours, both turbines would still have to be generating about 100MW, much of which would go to waste. Additionally, like all turbine-powered power plants, almost two-thirds of the energy generated by the turbines was lost due to heat. The efficiency of these turbine-generators was increased by implementing cogenerating turbines, which use the lost heat to create even more energy.
At the turn of the millennium, the steam turbine boiler plants were nearing the end of their efficient power supplying life cycles. Since the site of the power plant already had a well-supplied natural gas pipeline, a new natural gas generating station made more sense than implementing yet another fuel source. The new generating station makes use of reciprocating engine generators instead of steam turbines, combusting natural gas to operate an engine to generate electricity instead of boiling water to power steam turbines. Instead of one or two large generators, the plant implemented ten different 16.3MW Wartsila engine-generators running in parallel, for a total maximum output of 163MW. Other than maximum performance efficiency increases, using ten smaller generators allows some to be operating at maximum capacity while others are on standby or hibernating. That way the power plant as a whole can run at surprisingly high efficiencies while supplying variable amounts of energy to the grid. The new generating station emits 83% fewer ozone precursors, 33% less carbon dioxide, and it is 33% more efficient than the old natural gas steam turbine generators. Additionally, the new generators can also be fueled by ultra low sulphur diesel as a back-up, in case natural gas is unfeasible or unattainable for some reason in the future. The new generating station is capable of powering roughly 125,000 homes.
In an effort to further the efficiency of the reciprocating engine the U.S. Dept. of Energy has invested in a program called the Advanced Reciprocating Engine Systems (ARES), which orchestrates collaboration between Universities, manufacturers, national laboratories, and engine consultants . The end goal of ARES is to create a natural gas engine/generator system that is capable of achieving the following:
- 50% brake thermal efficiency (BTE); 80+% with combined heat and power (CHP)
- A maximum of 0.1 gm/bhp-hr NOx emissions
- Maintenance costs below $0.01/EkW-hr
- Maintaining cost competitiveness
Through the competitive funding and multi-participant R&D the ARES program is getting ever closer to its end goals. The continued research of Colorado State University and national laboratories and institutes such as Argonne National Laboratories, Gas Technology Institute, Oak Ridge National Laboratory, and many others the ARES program continues to achieve many milestones along its journey to the final end goals. Research will continue for many years to come to achieve an even more efficient and cost competitive engine/generator for natural gas power production.
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- Sridhar G., Paul P.J., Mukunda H.S. "Biomass derived producer gas as a reciprocating engine fuel-an experimental analysis".Biomass & Bioenergy. 2000
- Dorf, Richard C. "Components of Cogeneration Systems." The Engineering Handbook. 2nd ed. Hoboken: CRC, 2004. 75-12. Print