ASTM E974-00

Standard Guide for Specifying Thermal Performance of Geothermal Power Systems

SCOPE
1.1 This guide covers power plant performance terms and criteria for use in evaluation and comparison of geothermal energy conversion and power generation systems. The special nature of these geothermal systems makes performance criteria commonly used to evaluate conventional fossil fuel-fired systems of limited value. This guide identifies the limitations of the less useful criteria and defines an equitable basis for measuring the quality of differing thermal cycles and plant equipment for geothermal resources.  
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use .

General Information

• Status: Historical
• Publication Date: 09-Oct-2000
• ICS: 07.060 - Geology. Meteorology. Hydrology
• Technical Committee: E44 - Solar, Geothermal and Other Alternative Energy Sources
• Drafting Committee: E44.15 - Geothermal Field Development, Utilization and Materials

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E 974 – 00
Standard Guide for
Specifying Thermal Performance of Geothermal Power
Systems
This standard is issued under the fixed designation E 974; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The following sections describe a guide for determining the thermodynamic excellence of
geothermal power systems. This guide may be used to establish and compare performance levels of
alternative geothermal plant designs using equal or different resource conditions and is intended as a
means for supplying information in support of geothermal plant optimization.
It is also the purpose of this guide to promote the common use of pertinent comparison criteria for
geothermal power systems, and to discourage the use of some criteria which may range from less
useful to misleading.
1. Scope 3. Calculations
1.1 This guide covers power plant performance terms and 3.1 Fossil Fuel-fired Power Plants—Thermal efficiency and
criteria for use in evaluation and comparison of geothermal heat rate are useful and valid criteria for evaluation and
energy conversion and power generation systems. The special comparison of fossil fuel-fired power plants. Thermal effi-
nature of these geothermal systems makes performance criteria ciency is the ratio of net work generated to the heat that is
commonly used to evaluate conventional fossil fuel-fired theoretically available from the fuel. Conventional usage
systems of limited value. This guide identifies the limitations within the electric generating industry defines thermal effi-
of the less useful criteria and defines an equitable basis for ciency (in dimensionless form) as:
measuring the quality of differing thermal cycles and plant
h 5 3600/HR (1)
t
equipment for geothermal resources.
1.2 This standard does not purport to address all of the
where:
safety concerns, if any, associated with its use. It is the
3600 = kJ equivalent of 1 kWh, and
responsibility of the user of this standard to establish appro-
HR = heat rate, the ratio of energy supplied to the net
priate safety and health practices and determine the applica-
output, kJ/kWh.
bility of regulatory limitations prior to use.
3.1.1 Forfossilfuel-firedpowerplantsheatrateisexpressed
2. Significance and Use as:
2.1 Thermal efficiency and heat rate are frequently utilized HR 5 ~M 3 FC/W! (2)
F
to evaluate the thermodynamic quality of fossil fuel-fired
2 where:
power plants. Evaluation of geothermal systems using similar
M = fuel flow rate, kg/h,
F
definitions of thermal efficiency and heat rate is inappropriate,
FC = fuel higher heating value, kJ/kg, and
except for plants which operate on a cycle, such as binary
W = net output, kW.
plants. A utilization factor, defined as the ratio of net work
3.1.2 Thermal efficiency and heat rate are applicable to
output to the ideal work available from the geofluid, provides
plants which operate on a cycle, and include the effectiveness
a more equitable basis for evaluation of the thermodynamic
of energy conversion associated with the fuel combustion, the
excellence of geothermal systems.
effect of heat rejected in exhaust gases and condensate, and
allowance for equipment and balance of plant auxiliary power
1 losses. Thus, thermal efficiency and heat rate provide an
This guide is under the jurisdiction of ASTM Committee E44 on Solar,
equitable basis for ranking and comparing fossil fuel-fired
Geothermal,andOtherAlternativeEnergySourcesandisthedirectresponsibilityof
Subcommittee E44.20 on Geothermal Utilization.
plants of alternative design.
Current edition approved Oct. 10, 2000. Published November 2000.
3.2 Geothermal Power Plants—Geothermal plants using
Kestin, J., DiPippo, R., Khalifa, H.E., and Ryley, D. J., “Source Book on the
flashed steam (see Fig. 1a and Fig. 1b) do not operate on a
Production of Electricity From Geothermal Energy,” DoE/RA/28320-2, U.S. De-
partment of Energy, 1980, pp. 243–257. cycle but involve a series of energy conversion processes.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 974
FIG. 1 a Schematic of Single-Flash Steam Cycle
FIG. 1 b Schematic of Dual-Flash Steam Cycle (continued)
Thereforeevaluationofsuchplantsusingasimilardefinitionof
where:
thermalefficiencyandheatrateisinappropriateandwillleadto
E = ideal specific work available to the process within the
erroneousconclusionsregardingtheeffectivenessoftheplants.
natural bounds of the environment, kJ/kg,
The exception to this is the case of binary plants (see Fig. 1c) Q = well head mass flow rate, kg/s, and
o
which operate on a cycle and which receive a heat supply. (See W = net useful power, kW.
Sect. 3.2.2)
3.3.1 Utilization factor fulfills the objective of evaluating
3.3 Utilization Factor—A thermodynamically valid basis the quality of thermal cycles and for ranking the power
for comparing the thermodynamic excellence of geothermal potential of geothermal resources. It is important that the
energy conversion processes is provided by the utilization
power be explicitly defined as net power, as there may be
fac
...