CHARACTERISTICS

Auxiliary equipment includes all of the equipment except the boiler and turbine (e.g., fans, pumps, drive motors, valves, gauges, bag filters, water treatment, lighting) needed to complete the generation process. While essential to smooth operation of the power plant, many auxiliaries use energy and contribute to overall efficiency loss. The difference between gross and net generation is called parasitic load. For coal-fired power plants, approximately 6% of electrical output is lost to parasitic load. For plants that have a SO₂ scrubber installed, total electrical consumption by all auxiliary equipment may be as high as 9%. To improve efficiency, utilities can upgrade to more efficient auxiliary equipment, and can take auxiliary equipment out of operation to reduce auxiliary power requirements.

Upgrading of plant equipment can result in direct energy consumption savings, reduced maintenance costs, extended equipment life, and better power plant performance. Reducing the amount of fossil energy consumed in producing electricity will also result in a reduction of greenhouse gas emissions.

Some of the techniques that can be used to reduce this electrical requirement are: upgrading to higher-efficiency design motors; using variable speed drives on large fans and pumps; using higher-efficiency lighting and other auxiliary support equipment; converting from centrifugal to variable pitch axial flow fans; and improved electrostatic precipitator controls. Redesign of the path that the flue gas takes through the boiler, ductwork, and environmental control equipment can improve the efficiency of the production process by reducing the power requirements for fans, minimizing pluggage from fly ash, and increasing boiler output.

SIZE:
Varies. Parasitic load can be reduced by as much as 1%.

FEATURES:
Most of station auxiliary use powers the large, forced-draft and induced-draft fan motors as well as condensate, boiler feed and circulating water pump motors. By using air foils (instead of straight vanes) in fans and guarding against excessive pump clearances, equipment efficiency can be improved by 10%. The U.S. Energy Information Administration estimates that in 1998, U.S. parasitic load associated with steam turbines was 3%; parasitic load of renewable energy technologies is closer to 1%.

COST:
High efficiency motors typically cost about 20% more than standard motors, and save about 5% in electricity (depending on the size of the motor). Variable speed drive motors reduce electricity use by about 20%. Efficient lighting can result in energy lighting savings of about 50-60%. It is likely that all costs can be recovered by savings from improved operation.

CURRENT USAGE:
In the U.S. and other countries, utilities are beginning to upgrade their auxiliary equipment.

POTENTIAL USAGE:
Every utility can use upgraded auxiliary equipment.

ISSUES ASSOCIATED WITH IMPLEMENTING ACTION

• Augmenting existing plant controls can allow greater integrated control of the entire plant, especially where such control can decrease net heat rate.
• Can install variable speed motors.
• Wind turbines and other renewable energy technologies have none of the auxiliary equipment common to coal-burning power plants (coal pulverizers, fans, emission controls, etc.). However, parasitic load is not null; windfarms, for instance, use automatic control systems to control blade pitch and speed which affects generator electricity output.

CLIMATE CHANGE IMPACT

EMISSION EFFECT:
    

CONDITIONS FOR EMISSIONS MITIGATION:

• Emissions will be reduced directly because of increased efficiency of generation and distribution; and indirectly through reduced electricity demand. Emission reductions will correspond inversely to efficiency improvements–i.e., 10% improvement in efficiency will result in a 10% reduction in emissions.
• Renewable energy technologies produce no emissions.

EMISSION ESTIMATE:
Varies according to the fuel used for electricity generation.

COST-EFFECTIVENESS:
N/A as is site specific, but likely to be marginally cost-effective.

SECONDARY EFFECTS:
Varies.

RESOURCES

• Steam, Its Generation and Use, 40th Edition, Babcock & Wilcox, Barberton, Ohio.
• The U.S. Department of Energy sponsors a variety of programs designed to improve the efficiency of auxiliary equipment including: Motor Challenge, and the Golden Carrot Program for pumps, fans and drives. Information about these programs is available at the DOE website at http://www.doe.gov/

CONTACTS

Electric Power Research Institute
Industrial Technologies & Services
Palo Alto, CA
Tel: (614) 841-7585
http://www.epri.com/

U.S. Department of Energy
Office of Industrial Technologies
Marsha Quinn
Director, Technology Access
Washington, DC
Tel: (202) 586-2097
Fax: (202) 586-9234
quinn@ee.doe.gov http://www.oit.doe.gov