Page - 14 - in Water, Energy, and Environment - A Primer

growingrangeofenergy-dependentservices toconsumers thatgo well beyondwhatwas possible before. It follows that most governments will undertake policies to make it possible to provide these services using the least amount of energy feasible, to minimize economic costs and environmental and national security impacts (seeChapter 10 for a discussion of water and energy policies). For many years, in tandemwith the industrial revolution, this energywas provided mostly by the combustion of fossil fuels – coal, oil, and natural gas (see Chapter 6). This is still true today (globally, we have about 80%dependencyon fossil fuels) aswe approach the third decade of the 21st century, and will probably continue to be true for at least several more decades. Nevertheless, change in the energy sector is well underway as renewable energy in its various forms enters the energy mainstream. A comprehensive discussionof these technologies canbe found inChapter 8. 2.2 ENERGYREALITIES This change reflects several realities: fossil fuel reserves, while large, are finite and non-renewable on any timescale relevant to human history. Their combustion releases carbon dioxide into the atmosphere, which, unless captured and sequestered, has serious global warming consequences. The infrastructure for extracting and delivering fossil fuels is highly vulnerable to natural disasters, terrorist attacks, and other breakdowns. Their market prices are volatile, and energy imports constitute amajor drain on the importing country’s finances. It is also important to recognize that, onaglobal basis, energy isnot in short supply.OurSunpours6millionquadsof radiation annually into the Earth’s atmosphere, where one quad is a quadrillion (109) Btu. To put this number in context, the world currently consumes about 600 quads of energy annually as measured by commercial sales. This number is 10,000 times less than what we receive from the Sun, and is only 4 parts in Water,Energy, andEnvironment–APrimer14