Ask an Expert about Electricity, Natural Gas,
& Energy Efficiency


Have you ever wondered why shoes hanging on a power line don’t get fried? Or why natural gas flames are blue? Or whether garbage could someday be a source of energy? Now you can get answers to these and all your energy-related questions. Just Ask an Expert!

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NEW! How is turning on lights so much work?

Answer: Since turning on a light is such a simple thing to do, I think you must be asking about the “work” of the electrical transmission and distribution system, which brings electricity from the power plant to the light bulbs in your home or school. This system does indeed involve a lot of work! To learn more about it, check out the Travels of Electricity section of our website:

How much do solar panels cost?

How does solar energy financially make sense?

Answer: These two questions are similar, so I will answer them together. Depending on your location and the type of solar system you install, a typical home installation costs between $18,000 and $40,000. The panels themselves are about a third of the cost, ranging from $4,500 to $12,000. Then there are installation fees on top of this. The costs of installing a solar power system are offset, however, by money saved on energy bills each month, so the longer you have a system in place, the more money you get back from your initial investment. Installing a solar power system can make good financial sense for high energy users. It depends on the electric rates in your area, and the size of the solar system installed, but households with very high energy use could recoup their investment within as few as five years. A household that uses a very modest amount of energy might never earn back the cost of the investment, however.

What is a good list of resources for people who want to learn more about renewable energy sources?

How do windmills create electricity?

Answer: Technically, windmills do not create electricity, but wind turbines do. Windmills have been in use for about 1,200 years. They use the wind’s energy to do mechanical work, such as milling grain or pumping water. Wind turbines operate differently than windmills. Rather than using the wind’s energy for mechanical work, they use the power of the wind to spin a turbine generator and produce electricity. As the wind blows, it turns the blades of the turbine, which spins a magnet near a coil of copper wire. The spinning magnet causes the electrons in the coil of wire to move. This generates electricity, which is sent through power lines to where it is needed. You can read more about wind energy, and other forms of renewable energy, on this website by going to

Do you know about any other solar energy websites?

Answer: If you’ve already read about solar energy on this site and want to explore further, visit the US Energy Information Administration’s site at

How do photovoltaic cells work?

Answer: Photovoltaic cells (also called PV cells or solar cells) are very thin layers of silicon covered with special glass or plastic. When sunlight hits these cells, electrons are released. The electrons flow onto wires, forming direct current (DC), which is the same kind of current that flows from a battery. A four-inch silicon cell can produce about 1 watt of DC electricity.

I once saw a pair of shoes hanging from a power line. Why didn’t the shoes get burned up by the electricity in the line?

Answer: Shoes hanging on a power line don’t get burned for the same reason that birds standing on a power line don’t get shocked: They don’t give electricity a path to the ground, so electricity stays in the line and does not go through them. But if the shoes were to touch a power line and a power pole at the same time, they would provide a path to the ground and would get blasted with electric current. It wouldn’t be pretty! By the way, if you ever see someone throwing shoes up onto a line, tell them to stop! The shoes can damage the power line, or someone trying to get the shoes down could be seriously shocked or even killed.

Why does the flame on my stove burners look blue, but the flame of a campfire is yellow?

Answer: A natural gas flame burns hotter than a campfire. In general, cooler flames appear yellow, orange, or red, while hotter flames look blue or white. (Flecks of orange in your gas flames are OK, but if the flame is yellow, large, and flickering, the appliance may need a safety adjustment by a qualified repair person.)

I have heard that landfills can be a source of energy. How does that work?

Answer: Organic waste emits methane as it decomposes—or rots—in a landfill. Landfills can collect and treat the methane, and then sell it as a commercial fuel; or they can burn it to generate steam and electricity. Today, there are almost more than 600 gas energy landfill projects operating in the United States.