Part I of this three-part series set the stage for examining intermittent power sources, especially wind, as viable sources of electricity. Part 2 addresses one of the critical power considerations: power density.
In his MasterResource series, Vaclav Smil compared the power densities of a range of fuels for electricity production, which demonstrates the inadequacies of renewables. David MacKay also makes a useful contribution to this topic.[i] Table 1 summarizes the results, which take into account entire fuel cycles, transportation and transmission requirements for a range of assumptions.
Note that all renewable energy sources are ten to over a thousand times less effective than those serving our needs today, with wind providing one of the poorest performances of the renewable sources shown, outside of wood. Areas required for renewables are large because of the dispersed, and often remote, nature of their energy supply.…
Editor’s note: This is the conclusion of the series that provides an essential basis for the understanding of energy transitions and use. The previous posts in this series can be seen at:
Part I – Definitions
Part II – Coal- and Wood-Fired Electricity Generation
Part III – Natural Gas-Fired Electricity Generation
Part IV – New Renewables Electricity Generation
America’s dominant mode of electricity generation is via combustion of bituminous and sub-bituminous coal in large thermal stations. All such plants have boilers and steam turbogenerators and electrostatic precipitators to capture fly ash, but they burn different qualities of coal that may come from surface as well as underground mines, have different arrangements for cooling (once-through using river water or various cooling towers) and many have flue gas desulfurization to reduce SO2 emissions.…
Editor’s note: This is Part II of a five part series that provides an essential basis for the understanding of energy transitions and use. The opening post on definitions was yesterday.
Baseline calculations for modern electricity generation reflect the most important mode of the U.S. electricity generation, coal combustion in modern large coal-fired stations, which produced nearly 45% of the total in 2009. As there is no such thing as a standard coal-fired station I will calculate two very realistic but substantially different densities resulting from disparities in coal quality, fuel delivery and power plant operation. The highest power density would be associated with a large (in this example I will assume installed generating capacity of 1 GWe) mine-mouth power plant (supplied by high-capacity conveyors or short-haul trucking directly from the mine and not requiring any coal-storage yard), burning sub-bituminous coal (energy density of 20 GJ/t, ash content less than 5%, sulfur content below 0.5%), sited in a proximity of a major river (able to use once-through cooling and hence without any large cooling towers) that would operate with a high capacity factor (80%) and with a high conversion efficiency (38%).…