In a technological, computer-based world, we depend on reliable, high-quality electricity more than ever. Maintaining such power while increasing renewable electricity on our grids is a challenge we must understand and solve.
“Reliable” means electricity is available when needed, 24 hours a day, 365 days a year.
“Power quality” refers to electricity delivered at a smooth 60 hertz (cycles per second). The grid is designed to operate at this frequency. If frequency changes beyond a certain level, the grid is designed to protect itself from expensive, long-term damage. This can be done by turning off some customers (“dropping load”) if necessary and, in extreme cases, shutting down entirely.
In our homes and businesses, electronic devices are also designed to operate on the 60 hertz frequency. In sensitive electronic devices electrical surges and ebbs can disrupt or distort operations and even damage or destroy the devices.
Many renewable resources are variable, or intermittent. Wind is a good example. Hawaii’s typical tradewinds may blow harder on some days, softer on others, and at times not at all. Wind direction and speed can change minute to minute. All this affects the electrical output of wind turbines.
On small, stand-alone grids like those in the Hawaiian Islands, these fluctuations must be offset by “firm” generators. One challenge is that the wind can change quicker than typical electric generators. Maintaining 60 hertz frequency can strain generators (and the people who operate them).
This problem is less severe for large utilities on the continental U.S. because the variable renewable resource may be a much smaller percentage of total generation than on Hawaii’s small grids. As a result, power can be picked up from interconnected utilities.
New technologies -- like the electronic shock absorber invented and patented by engineers at Hawaiian Electric Company -- can help smooth the ebbs and surges of wind in the short term.
Large-scale electric storage -- including very large chemical, mechanical and electronic “batteries” -- is being developed. But some technologies are in very early stages of development. At present, large batteries or other storage can be very expensive, adding to the cost of every kilowatt hour of electricity produced.
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