The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [39]
So why, then, haven’t we plastered CSP plants all over our deserts? One reason is that because there are still so few built, the necessary mirrors and other equipment are still specialty products and thus quite expensive. These costs are expected to fall as the industry grows, but at the moment, with electricity prices of at least twelve cents per kilowatt-hour, CSP is still less economical than conventional power plants. Another challenge is the lack of high-voltage transmission lines connecting hot, empty deserts to the places where people actually live. All the electricity production in the world is worthless if it can’t be delivered to customers. This entails running hundreds of miles of high-voltage direct-current (HVDC) power cable, which suffers lower transmission losses than traditional alternating current (AC) transmission lines. HVDC is already used to transmit electricity over great distances in Africa, China, the United States, Canada, and Brazil but, like all major infrastructure, is quite expensive. An undersea HVDC cable between Norway and the Netherlands cost about a million euros per kilometer in 2008.161 So while doable, channeling solar power from the world’s deserts to cities will require major capital investments in infrastructure.
One disadvantage that afflicts not just CSP but all forms of solar and wind energy is energy storage. Few of us marvel that a light beam appears with the simple click of a flashlight button. Yet, imagine if the flashlight were powered not by battery but by hand-crank, with no battery storage whatsoever. Use of this flashlight would require constant hand-cranking (I would simply give up and sit in the dark). Furthermore, for maximum efficiency the turning hand would have to exactly match the electricity requirement at all times: Without battery storage, any excess power generated (i.e., beyond the wattage of the bulb) is lost; any deficit causes the bulb to dim.
Scaling this problem up, we see that meeting society’s volatile electricity needs in a nonwasteful manner poses an enormous challenge. Demand fluctuates by the week, hour, and minute in response to all sorts of things, from business cycles to the commercial breaks of popular television programs. Power utilities must constantly adjust their production of electricity accordingly. Too much capacity wastes money as power plants make unused electricity; too little capacity triggers brownouts or rolling power outages.
It’s hard enough to predict fluctuations on the demand side. Solar and wind sources—because they wither or die on calm days, cloudy days, and at night—add new volatility on the supply side. In a world powered substantially from wind and solar sources, avoiding brownouts will require vast “smart grids,” meaning highly interconnected and communicative transmission networks, plenty of backup capacity from conventional power plants,162 and new ways to store excess electricity for times of deficit.
Storing excess electricity is challenging. One way is “pumped storage” using water. If excess electricity becomes available, it is used to pump water uphill, from a reservoir or tank, to another one at higher elevation. When electricity is wanted, the water is released from the upper to lower container again, flowing by force of gravity over turbines to make electricity. Pumped storage is relatively efficient, inexpensive, and has been around for a long time, but requires lots of water and reservoirs.163
An exciting storage idea is to tap into the batteries of millions of parked electric cars whenever they plug into the power grid. By communicating with the