The good news on the dust front, though, is that some water-free ideas exist for cleaning PV panels—they just haven’t been produced at large scale yet. The best possibilities are electrostatic cleaning, where a charge flowing over a panel can essentially push the dust out of the way (the technology was developed initially by NASA for lunar and Mars missions) or mechanical systems that would just brush off a panel once a day. For CSP plants where windblown dust and sand can permanently erode the mirrors, tilting them down out of an oncoming sandstorm is one way to keep the plants viable.
From deserts to market
And then there’s transmission, which Randy Hickok, the senior vice president of asset management at Ivanpah co-owner NRG Solar, says could be the biggest hurdle. “Traditionally power plants haven’t been in deserts, so you don’t have a lot of high-voltage transmission running to these out-of-the-way locations,” he says. “For a lot of your best solar resource, you don’t have available transmission, and siting transmission is not an easy task.” High-voltage lines can cost millions of dollars per mile.
But again, the technical side of this is not the deal breaker. Darling says we are perfectly capable of building long lines to remote locales, and with high-voltage direct current (HVDC) the efficiency losses are quite low, on the order of only a few percent every thousand kilometers.
Hickok says that developers have rushed to build new facilities in locations where few upgrades to a transmission system are needed, but those “low-hanging fruit” possibilities get exhausted relatively quickly. The really big desert-solar ideas, like DESERTEC’s plan to power all of Europe with HVDC lines across the Mediterranean from north Africa, would require such a massive investment in transmission lines that they’re unlikely to move forward on meaningful timescales.
And even DESERTEC—which had led the calls for massive desert renewables development—has scaled back its planet-saving rhetoric in recent years as the challenge of getting started has grown. Thiemmo Gropp, director of DESERTEC, says the foundation’s main goal now is to help build some impressive pilot projects that will illustrate to the rest of the world that building big in the desert is doable. The group has partnered with Saudi Arabia, which hopes by 2030 to build an astonishing 54 gigawatts of renewable energy (41 GW from solar, essentially all of it in the vast Saudi desert) and is also on board with some initial projects in Morocco. Gropp agrees that the engineering challenges are not the primary obstacle, although of course the technology will continue to improve. “There are no serious hurdles,” he says. “Right now we have a car like in the 1920s or 1930s, we don’t have mass production of 2013; but it’s got an engine, it’s got 4 wheels, it works. I don’t see any technical principle hurdles.”
Out in the Mojave, Ivanpah is clearly a desert success story, but it can’t obscure the ongoing struggles that accompany it. BrightSource Energy, co-owner of the plant along with NRG Solar, has this year shelved a full gigawatt of other desert solar ideas. Many CSP plants have either been canceled or switched to more modest PV designs as panel prices have plummeted in recent years, showing again that the effort remains at the whims of fickle market dynamics. It is good to know, though, that whereas other planetary saviors (like, say, carbon capture and storage) languish in technological and cost purgatory, building solar power where the sun shines brightest doesn’t seem to worry those who are doing the building.