WHICH SOURCES ARE LOCAL?
Transmitting energy has always been a complex but largely invisible problem. Most of our individual energy use comes from gasoline in our cars. That oil product is drilled, shipped, refined, and trucked to the pump. We also rely on natural gas at home, another drilled, refined, piped product. And lastly there is electricity, which is usually transmitted great distances along power lines, unless you use solar panels or a generator. Modern energy sources are hardly local.
Oil is the most notorious of foreign energy sources. Roughly half is produced domestically. The other half comes from Canada, Saudi Arabia, Nigeria, Venezuela, Mexico, and other countries, many of which suffer from political instability or non-democratically-elected governments, and often at a pretty steep environmental and social cost to people who are economically disadvantaged. Top oil regions producing for the U.S. market in 2009 here.
Coal and natural gas are mined or drilled and used primarily within the United States, as is geothermal, and solar thermal. Solar photovoltaic and wind use energy sources that are local but the equipment is often imported, particularly from Asia.
In recent years, there’s been increased interest in distributed generation, the use of many, small energy systems spread out over a large area instead of — or complementary to — a few large power plants located farther away. Solar panels on a house, a diesel generator in the backyard, or a wind turbine that powers a farm are all examples of distributed generators.
Not all sources can be miniaturized and distributed on small scale, for example nuclear, geothermal, and hydroelectric power.
HOW DIFFERENT SOURCES GET PLUGGED INTO THE GRID
The most dependable sources of energy use are fuels that can be stored: fossil fuels, biofuels, biomass (like garbage and wood wastes), and nuclear. Our energy markets and transmission lines were designed to operate with these kinds of fuels, because energy has to be delivered when it’s needed, and energy demand fluctuates hourly: click graph to enlarge energy curve a single day in California. That requirement makes it especially difficult to shoehorn in energy sources like wind and solar.
Unfortunately, today there is no great way to store large amounts of electricity. Almost all has to be produced within moments of when it’s consumed. Furthermore, some sources can’t be installed just anywhere, and they can require expensive transmission line investment to plug into the grid. Wind investments are made in windy locations, or even offshore. Solar plants may be constructed in distant locations like the desert.
However, so-called distributed solar, which is small solar panels placed in the city, such as on parking lots and on utility poles, is an easy way to bypass the need for massive amounts of transmission. Furthermore, many new battery and fuel cell technologies are being developed for small scale electricity storage, perhaps one day allowing for greater integration of a variety of intermittent sources.