Steam Motors Compressed Air

Benchmark the Fuel Cost of Steam

Generation

Effective Cost of Steam Benchmarking the fuel cost of steam generation ($/1000 lbs of steam) is an effective way to assess
the efficiency of your steam system. This cost is dependent upon fuel type, unit fuel cost, boiler
The effective cost of steam efficiency, feedwater temperature, and steam pressure. This calculation provides a good first
depends on the path it follows approximation for the cost of generating steam and serves as a tracking device to allow for boiler
from the boiler to the point of performance monitoring. Table 1 shows the heat input required to produce one pound of saturated
use. Take a systems approach steam at different operating pressures and varying feedwater temperatures. Table 2 lists the typical
and consider the entire boiler energy content and boiler combustion efficiency for several common fuels.
island, including effect of blow-
down, parasitic steam consump-
Table 1. Energy Required to Produce One Pound of Saturated Steam (Btu)*
tion, deaeration, etc. Further
complications arise due to the Operating Feedwater Temperature, F
process steam loads at different Pressure, psig 50 100 150 200 250
pressures, multiple boilers, and 150 1,178 1,128 1,078 1,028 977
waste heat recovery systems. To 450 1,187 1,137 1,087 1,037 986
determine the effective cost of 600 1,184 1,134 1,084 1,034 984
steam, use a combined heat and * Calculated from steam tables based on the difference between the enthalpies of saturated steam and feedwater.
power simulation model that
includes all the significant effects.
Table 2. Energy Content and Combustion Efficiency of Fuels
Multi-Fuel Capability Fuel Type (sales unit) Energy Content Combustion
(Btu/sales unit) Efficiency (%)
For multi-fuel capability boilers,
Natural Gas (therm) 100,000 81.7
take advantage of volatility in
Natural Gas (cubic foot) 1,030 81.7
fuel prices by periodically ana-
Distillate/No. 2 Oil (gallon) 138,700 84.6
lyzing the steam generation cost
Residual/No. 6 Oil (gallon) 149,700 86.1
and use the fuel that provides the
Coal (ton) 27,000,000 87.6
lowest steam generation cost.
Note: Combustion efficiency is based on boilers equipped with economizers and air preheaters and 3% oxygen in flue gas.

Higher Versus Lower Data from the above tables can be used to determine the cost of usable heat from a boiler or
Heating Values other combustion unit. The calculations can also include operating costs of accessories such
Fuel is sold based on its gross or as feedwater pumps, fans, fuel heaters, steam for fuel atomizers and soot blowing, treatment
higher heating value (HHV). If, chemicals, and environmental and maintenance costs.
at the end of the combustion
process, water remains in the
form of vapor, the HHV must be
Example
reduced by the latent heat of A boiler, fired with natural gas costing $0.30/therm, produces 450 psig saturated steam and is
vaporization of water. This supplied with 230F feedwater. Using values from the tables, calculate the cost of producing
reduced value is known as the steam.
lower heating value (LHV).
0.3 ($/therm) 100
Steam Cost = x 1000 x 1006 (Btu/lb) x = $3.69/1000 lbs
100,000 (Btu/therm) 81.7

For additional information on Suggested Actions

industrial energy efficiency Determine your annual fuel costs based on utility bills.
measures, contact the OIT
Clearinghouse at (800) 862-2086. Install a steam flowmeter in your facility and calculate your steam generation cost. Compare
this with the benchmark value.
Using a systems approach, do a thermoeconomic analysis to determine the effective cost of
steam. (See sidebar: Effective Cost of Steam)

OFFICE OF INDUSTRIAL TECHNOLOGIES

ENERGY EFFICIENCY AND RENEWABLE ENERGY U.S. DEPARTMENT OF ENERGY
About DOEs Office of Industrial Technologies
The Office of Industrial Technologies (OIT), through partnerships with industry,
government, and non-governmental organizations, develops and delivers advanced
energy efficiency, renewable energy, and pollution prevention technologies for industrial
applications. OIT is part of the U.S. Department of Energys Office of Energy Efficiency
and Renewable Energy.
OIT encourages industry-wide efforts to boost resource productivity through a strategy
called Industries of the Future (IOF). IOF focuses on the following nine energy and
resource intensive industries: BestPractices is part of the Office of
Industrial Technologies (OITs) Industries
Agriculture Forest Products Mining of the Future strategy, which helps the
Aluminum Glass Petroleum countrys most energy-intensive
industries improve their competitiveness.
Chemicals Metal Casting Steel BestPractices brings together the best-
OIT and its BestPractices program offer a wide variety of resources to industrial available and emerging technologies
and practices to help companies begin
partners that cover motor, steam, compressed air and process heating systems. improving energy efficiency, environmental
For example, BestPractices software can help you decide whether to replace or rewind performance, and productivity right now.
motors (MotorMaster+), assess the efficiency of pumping systems (PSAT), or determine
BestPractices focuses on plant systems,
optimal insulation thickness for pipes and pressure vessels (3E Plus). Training is available where significant efficiency improvements
to help you or your staff learn how to use these software programs and learn more and savings can be achieved. Industry
about industrial systems. Workshops are held around the country on topics such as gains easy access to near-term and
Capturing the Value of Steam Efficiency, Fundamentals and Advanced Management long-term solutions for improving the
performance of motor, steam, compressed
of Compressed Air Systems, and Motor System Management. Available technical air, and process heating systems. In
publications range from case studies and tip sheets to sourcebooks and market assessments. addition, the Industrial Assessment Centers
The Energy Matters newsletter, for example, provides timely articles and information on provide comprehensive industrial energy
evaluations to small and medium-size
comprehensive energy systems for industry. You can access these resources and more by manufacturers.
visiting the BestPractices Web site at www.oit.doe.gov/bestpractices or by contacting the
OIT Clearinghouse at 800-862-2086 or via email at clearinghouse@ee.doe.gov.

F OR A DDITIONAL I NFORMATION ,
P LEASE C ONTACT:

Eric Lightner
Office of Industrial Technologies
Phone: (202) 586-8130
Fax: (202) 586-1658
Eric.Lightner@ee.doe.gov
www.oit.doe.gov/bestpractices

OIT Clearinghouse
Phone: (800) 862-2086
Fax: (360) 586-8303
clearinghouse@ee.doe.gov

Please send any comments,

questions, or suggestions to
webmaster.oit@ee.doe.gov

Visit our home page at

www.oit.doe.gov

Office of Industrial Technologies

Energy Efficiency
and Renewable Energy
U.S. Department of Energy
Washington, D.C. 20585

DOE/GO-102000-1115
November 2000
Steam Tip Sheet #15