Therm
The therm (symbol, thm) is a non-
Definitions
- Therm (EC) ≡ 100000 BTUISO[2]
- Therm (US) ≡ 100000 BTU59 °F[3]
- = 105480400 joules
- ≈ 29.3001111111111 kWh.
- Therm (UK) ≡ 105505585.257348 joules[4]
- ≡ 29.3071070159300 kWh
Decatherm
A decatherm or dekatherm[5] (dth or Dth) is 10 therms, which is 1,000,000 British thermal units or 1.055 GJ.[6][7] It is a combination of the prefix for 10 (deca, often with the US spelling "deka") and the energy unit therm. There is some ambiguity, as "decatherm" uses the prefix "d" to mean 10, where in metric the prefix "d" means "deci" or one-tenth, and the prefix "da" means "deca", or 10, though decatherm may use a capital "D". The energy content of 1,000 cubic feet (28 m3) natural gas measured at standard conditions is approximately equal to one dekatherm.
This unit of energy is used primarily to measure natural gas. Natural gas is a mixture of gases containing approximately 80% methane (CH4) and its heating value varies from about or 10.1 to 11.4 kilowatt-hours per cubic metre (975 to 1,100 Btu/cu ft), depending on the mix of different gases in the gas stream. The volume of natural gas with heating value of one dekatherm is about 910 to 1,026 cubic feet (25.8 to 29.1 m3). Noncombustible carbon dioxide (CO2) lowers the heating value of natural gas. Heavier hydrocarbons such as ethane (C2H6), propane (C3H8), and butane (C4H10) increase its heating value. Since customers who buy natural gas are actually buying heat, gas distribution companies who bill by volume routinely adjust their rates to compensate for this.[8]
The company Texas Eastern Transmission Corporation, a natural gas
In spite of the need for adjustments, many companies continue to use cubic feet rather than dekatherms to measure and bill natural gas.[12][13]
Usage
United Kingdom regulations were amended to replace therms with joules with effect from 1999, with natural gas usually retailed in the derived unit, kilowatt-hours. Despite this, the wholesale UK gas market trades in therms. In the United States, natural gas is commonly billed in CCFs (hundreds of cubic feet) or therms.
Carbon footprint
According to the
See also
References
- ^ IEEE Std 260.1-2004
- ^ Official Journal L 073, P. 0114 27 March 1972
- ^ 15 USC Chapter 6 Archived 2006-01-25 at the Wayback Machine
- ^ The Units of Measurement Regulations 1995
- ^ Jerry Knight (22 January 1978). "Gas Utilities Stepping Up Efforts to Add Customers". The Washington Post. Retrieved 1 June 2016.
- ISBN 978-1-304-52087-6.
- ISBN 978-0-88173-543-7.
- ^ Its (1977). Bulletin. The Univ. p. 300.
- ^ Proceedings. International Society of Hydrocarbon Measurement. 1982. p. 394.
- ^ Public Utilities Reports. Lawyers Cooperative Publishing Company. 1986. p. 281.
- ^ Standard & Poor's (1997). Standard and Poor's Smallcap Six Hundred Guide. McGraw-Hill.
- ISBN 978-0-08-094943-7.
- ISBN 978-0-88173-648-9.
- ^ epa.gov "Greenhouse Gases Equivalencies Calculator - Calculations and References"