Part 1: In the first part of a ten part series, NPR provided some background information on the nation’s electric grid. It is largely unchanged since the days of Thomas Edison, contains 5.5 million miles of wires (130 million meters) connecting houses and business to the grid)and generates 950GW of electricity at peak usage (more than 50 times the energy produced by the Three Gorges Dam in China, the world’s largest hydroelectric project). One of the major problems facing the grid is the fact that electricity cannot be stored. The amount generated must always equal the amount used. Coal, gas and nuclear provide a consistent, reliable source of energy to generate electricity. The smart grid will allow for seamless integration of electricity from intermittent renewable sources. Xcel Energy’s $100 million (US) smart grid pilot program (SmartGridCity in Boulder, Colorado) includes batteries in people’s residences to store the energy produced by wind and solar. These batteries can store energy until needed at peak usage, reducing the utilities’ need for “firing up an expensive generator.” The batteries are provided by Xcel Energy and Grid Point, whose mission is “to make the Smart Grid a reality by aligning the interests of electric utilities, consumers and the environment.”

Click on the map above for an interactive tour of the electric grid

Part 2: In the second part of the series, NPR reporter Christopher Joyce looked at solutions for the influx of renewable energy. Electricity put onto the grid must be consumed, it cannot circulate indefinitely. Higher demand days, those in which air conditioning units are cranked up, require an increase in generation. However, starting and stopping nuclear or coal-fired power plants is inefficient. Intermittent power (wind and solar) causes problems for the grid by leading to an uneven power supply. In situations where wind or solar energy is unavailable but demand is high, base load power (coal and nuclear) must replace the lost generation from the renewable sources. In order to even out the spikes and valleys in energy production from these sources, some have suggested storing the excess, off-peak energy. One thought to help capture surplus energy generated by renewable energy is charging batteries, like those found in hybrid gasoline-electric or plug-in electric vehicles. $600 million (US) from the federal stimulus bill has been made available for so-called storage solutions. One possibility is a flywheel, “a spinning metal rotor, floating in a vacuum inside a steel cylinder.” Gene Hunt, of Beacon Power in Massachusetts, says one of the company’s flywheels “spins at 16,000 revolutions per minute.” The wheel works similarly to a potter’s wheel, which “is powered by the human foot, pumping the pedal up and down. It turns this wheel which has a certain weight, it brings it up to a speed, and when you take your foot away, it continues to spin. It’s using the energy that’s stored in there.’” The flywheel, which runs on electricity, stores excess power from the grid as kinetic, or rotational energy. “Beacon is building flywheel ‘farms’ that can return that energy as electricity in short bursts when operators need to meet a spike in demand on the grid.” Another company working toward a solution is Grid Point, who has teamed up with Xcel Energy. Grid Point’s power storage device, being used in Boulder, can be placed in individual homes. By hooking up the devices to a network, the company can determine the amount of energy available in the batteries. In addition, Grid Point sees vehicles as a part of the solution to storing the intermittent renewable energy.

Check back for a summary on parts 3 and 4 of the series.

- Eric Wilson