Abstract: . . .  watt-hours. Power stations are normally quoted with their maximum output power capacity: a large, 1 GW, power station could in theory produce 8.76 TWh each year running continuously (there are 8,760 hours in a year). Electricity demand in the United Kingdom in 2002 was just under 400 TWh, indicating a mean rate of use of around 45 GW. Total installed generating capacity was 77 GW, and the maximum demand met at any time in that year was just over 60 GW. The minimum demand on a summer night may fall below 20 GW. An average household consumes 3,300 kWh (or 3.3 MWh) of electricity each year. As a rule of thumb, electricity suppliers therefore often work to an average power requirement of 0.5 kW per household, although there will be considerable RENEWABLE ENERGY: PRACTICALITIES 127 variation over the course of a day—one kettle, for instance, consumes at a rate of over 2 kW for the short time that it is on. For Combined Heat and Power (CHP) generators, output is measured using MWe as the amount of electrical power produced, and MWth as the amount of thermal (in other words heat) power. Carbon units and emissions Emissions to the atmosphere of greenhouse gases are by convention quoted in terms of the carbon (C) equivalent amount, as carbon dioxide (CO2) is the principal greenhouse gas occurring as a by-product of burning fossil fuels. Amounts are often described in millions of tonnes (Mt) of carbon, MtC. Occasionally, however, emissions are expressed in terms of CO2 equivalence (for instance, . . .
. . .  Power stations are normally quoted with their maximum output power capacity: a large, 1 GW, power station could in theory produce 8.76 TWh each year running continuously (there are 8,760 hours in a year). Electricity demand in the United Kingdom in 2002 was just under 400 TWh, indicating a mean rate of use of around 45 GW. Total installed generating capacity was 77 GW, and the maximum demand met at any time in that year was just over 60 GW. The minimum demand on a summer night may fall below 20 GW. An average household consumes 3,300 kWh (or 3.3 MWh) of electricity each year. As a rule of thumb, electricity suppliers therefore often work to an average power requirement of 0.5 kW per household, although there will be considerable RENEWABLE ENERGY: PRACTICALITIES 127 variation over the course of a day—one kettle, for instance, consumes at a rate of over 2 kW for the short time that it is on. For Combined Heat and Power (CHP) generators, output is measured using MWe as the amount of electrical power produced, and MWth as the amount of thermal (in other words heat) power. Carbon units and emissions Emissions to the atmosphere of greenhouse gases are by convention quoted in terms of the carbon (C) equivalent amount, as carbon dioxide (CO2) is the principal greenhouse gas occurring as a by-product of burning fossil fuels. Amounts are often described in millions of tonnes (Mt) of carbon, MtC. Occasionally, however, emissions are expressed in terms of CO2 equivalence (for instance, in . . .
--3000,2,750,3169,354673