Ever since the Industrial Revolution, the world has been hungry for energy. A hundred years ago, developing technologies relied on fossil fuels—and that reliance has only grown with time. Today, most power plants burn coal, oil, or natural gas; cars run on oceans of gasoline; and people heat their homes with oil or gas. But fossil fuels won't last forever, and their overuse poses serious environmental problems. We need new technologies to supply our energy without taking such a heavy toll on the planet.
There are lots of reasons to be optimistic about the future. We're at an exciting and historic crossroads: Conventional power sources such as fossil fuels are making room for carbon-neutral, earth-friendly alternatives. This chapter gives an overview of renewable energy and some of the emerging technologies.
As you've no doubt heard, the climate is changing—largely due to human activity. Global warming refers to an average increase in the temperature on the earth's surface and in the troposphere, the atmosphere's lowest layer. This warming contributes to climate changes, which can have a host of consequences, like shrinking polar ice caps, rising sea levels, and changes in weather patterns that can affect crops and even drive some species to extinction.
A big cause of global warming are the greenhouses gases that get released when people burn fossil fuels like coal, petroleum, and natural gas. These gases—which include carbon dioxide (CO2), methane, and water vapor—aren't bad in themselves. Every time you take a breath, you exhale CO2, which plants take in and then give off oxygen. This cycle works great—when it's in balance. But increased fossil fuel consumption and deforestation has thrown the cycle out of whack.
With too many greenhouse gases, radiation from the sun gets into the atmosphere but can't leave because the gases absorb and then reemit it, which raises the earth's temperature. This greenhouse effect traps heat in the troposphere. Like greenhouse gases, this effect isn't bad in itself—it lets the earth support life—but too much of it is causing global warming and messing up the climate.
According to the U.S. EPA, average temperatures worldwide could increase from 3.2–7.2° F (about 2–4° C) above 1990 levels in less than a hundred years. When you're shoveling snow on a frigid morning, heating things up a bit might seem great. But global warming can cause lots of problems, like the spread of diseases (as host insects expand their range); extreme weather like hurricanes, tornadoes, flooding, and drought; extinction of plants and animals; and food and water shortages.
One way for you to reduce greenhouse-gas emissions is by using less energy—and this book is full of ways to do that. If everyone made a few small, simple changes, we'd all use less power and spew less pollution into the atmosphere. But we need bigger changes, too. The U.S. Energy Information Administration says that 86% of the power produced in the U.S. comes from fossil fuels, and only a measly 6% from renewable sources. To reduce global warming, the government needs to invest in research and practical applications for energy that's clean, sustainable, and renewable.
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Acid rain is another serious problem caused by burning fossil fuels. The culprits are sulfur dioxide and nitrogen oxides, which react with water vapor and other gases to produce sulfuric acid and nitric acid. These acids upset the balance of rivers, lakes, and soil and damage trees, buildings, statues, and even human health by damaging lungs if inhaled.
