being transferred
Examples of Power Examples of power are limited only by the imagination, because there are as many types as there are forms of work and energy. See Table 7.3 for some examples. Sunlight reaching Earths surface carries a maximum power of about 1.3 kilowatts per square meter kW/m 2 . A tiny fraction of this is retained by Earth over the long term. Our consumption rate of fossil fuels is far greater than the rate at which they are stored, so it is inevitable that they will be depleted. Power implies that energy is transferred, perhaps changing form. It is never possible to change one form completely into another without losing some of it as thermal energy. For example, a 60-W incandescent bulb converts only 5 W of electrical power to light, with 55 W dissipating into thermal energy. Furthermore, the typical electric power plant converts only 35 to 40% of its fuel into electricity. The remainder becomes a huge amount of thermal energy that must be dispersed as heat transfer, as rapidly as it is created. A coal-fired power 6 plant may produce 1000 megawatts; 1 megawatt MW is 10 W of electric power. But the power plant consumes chemical energy at a rate of about 2500 MW, creating heat transfer to the surroundings at a rate of 1500 MW. See Figure 7.25.