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86 Managing Global Warming

Fig. 3.22 Photo of Pelamis Wave-Energy Converter on site at the European Marine Energy
Test Centre (EMEC), Orkney, Scotland, 2007. This converter was rated at 750kW el and was the
world’s first offshore wave power machine to generate electricity into grid system [16].
The prototype is 120m long and 3.5m in diameter. It consisted of four tube sections linked
by three, shorter, power-conversion modules.
Photo taken from Wikimedia Commons, author/username P123.

(2) Capacity factor of a plant: Net capacity factor of a power plant is the ratio of the actual
output of a power plant over a period of time (usually, during a year) and its potential output
if it had operated at a full nameplate capacity the entire time. To calculate the capacity fac-
tor, the total amount of energy a plant produced during a period of time should be divided by
the amount of energy the plant would have produced at the full capacity. Capacity factors
vary significantly depending on the type of a plant. Average capacity factors of various
power plants are listed in Tables 3.2–3.4 [1,2].

3.2 Share and operation of various energy sources
in an electrical grid

The fraction of total global energy used for electrical power generation is presently
about 42% [21]. This fraction is expected to increase with increasing known gas
reserves (especially, in United States, China, and Australia) and falling prices and
resulting enhanced energy exports. Of that fraction some 85% is from gas, coal,
and oil. Carbon resources are expected to continue to dominate despite the fuel
switching from coal to natural gas and subsidies for noncarbon sources like wind
and solar. The mix of sources deployed in any particular electrical generation system
varies widely [22]. Electrical generation sources and the energy “mix” are dependent
on a number of key factors:
(a) The availability locally or nationally of specific fuel resources, particularly, coal, natural
gas, uranium, and/or oil. Therefore, net energy-importing countries and regions (e.g., Japan,
United Kingdom, and mainland Europe) will likely see more diversification of supply alter-
natives and government policies for subsidies and net metering pricing.