There have been a number of interesting things on the solar power front finding their way into my browser over the past couple of weeks, so I figured I'd pull together something for the blog. The "news" part of this, of course, was the announcement of the Ivanpah Solar Electric Generating System going on-line out on the California-Nevada border, which is going to cover 3,500 acres of desert and provide electricity for 140,000 homes. The U.S. has been lagging behind most other countries in terms of making investments in solar power, and it's interesting that this particular installation is co-owned by Google.
There are so many frustrating things with the renewable power biz ... from the intractability of the nuclear power industry that's making it an uphill battle for 4th generation reactors (using Thorium and other cleaner, safer systems) to the NIMBY factors of wind farming ... and the core realities of solar are probably the most frustrating, because the energy is there, it's just getting it to the point where we can get it. Solar energy hitting the Earth amounts to something like 8.2 million "quads BTU" (one quadrillion British Thermal Units of energy) per year ... while the entire human race is only using (in all forms of energy) less than 500 "quads" per year. The issue is, of course, how to get that nice radiant solar energy that's pouring down on us into a form we can use.
Frankly, when I see something like this new "mirror farm" spreading out over five square miles "just" to provide power to 140,000 homes, I figure we're doing something wrong. Sure, that works out to only about a 33' square chunk of land per account, but given how much raw power is incoming, that seems to be positively "stone age". Plus, at the Ivanpah site they're not even attempting to directly harvest the power, but using the sun's heat to drive standard generators. Here's how Smithsonian described it:
Unlike photovoltaic technology, which converts solar radiation directly into electricity, the Ivanpah facility generates heat. More than 170,000 mirrors will gather tremendous amounts of sunlight and focus it on three towers filled with water, raising temperatures to more than 1,000 degrees Fahrenheit and producing steam that spins turbines that generate electricity.
I can't help but think that in a not-too-distant future this is going to seem like bashing rocks together!
Of course, we can't plan for technologies that we don't have, so we currently have to deal with the realities of what can be produced. Up in Evanston, a big Walgreens has recently "gone off the grid" with roof-top solar panels, and the efficiency of these are getting better year by year, but one has to suspect that a true solar solution is likely going to come from some technology that's not yet been developed (efficient panels coupled with efficient storage that could be easily and inexpensively installed on individual homes, offices, etc.). However, another site, that of the Land Art Generator Initiative, has a fascinating look at how much land area would be needed (as of 2009) to produce the energy needs of the planet. They go into a lot of detail but come up with an answer of "the size of Spain" ...
Dividing the global yearly demand by 400 kW•h per square meter (198,721,800,000,000 / 400) and we arrive at 496,804,500,000 square meters or 496,805 square kilometers (191,817 square miles) as the area required to power the world with solar panels. This is roughly equal to the area of Spain. At first that sounds like a lot and it is. But we should put this in perspective.
If divided into 5,000 super-site installations around the world (average of 25 per country), it would measure less than 10km a side for each. The UAE has plans to construct 1,500MW of capacity by 2020 which will require a space of 3 km per side. If the UAE constructed the other 7 km per side of that area, it would be able to power itself as a nation completely with solar energy. The USA would require a much larger area and approximately 1,000 of these super-sites.
They also have an interesting map showing what size areas this would translate to around the globe. And, remember, this is based on the generating capabilities of 2009, which have improved since, and are, no doubt, going to be pushed into new efficiencies (or whole new systems) in the years ahead.
The other news item that I saw was that IBM has been making additional strides in the designs for its High Concentration Photo Voltaic Thermal (HCPVT) system. I'd done a post about this some time back (which I realized when seeing the video in the piece), but the design has evolved from a plain parabolic mirror into an much larger array of smaller mirrors that focus the sunlight at concentrations over 2,000x onto liquid-cooled high-performance PV chips. Here's a bit from an Engadget story that features the full release from IBM:
... an affordable photovoltaic system capable of concentrating, on average, the power of 2,000 suns, with an efficiency that can collect 80 percent of the incoming radiation and convert it to useful energy. The proposed system can be built anywhere sustainable energy, drinkable water and cool air are in short supply at a cost of three times lower than comparable systems.
I'm guessing that a system based on these HCPVT collectors would be many times more efficient than what was the baseline for those 2009 figures, so the necessary land area would be greatly reduced.
To close, I figured I'd toss in one more quote, from a FAQ on solar from the Solar Institute at George Washington University, and a link to another (very detailed) Solar FAQs from Sandia National Labs. Here's another look at "how much solar is available":
The amount of energy from the sun that falls on Earth's surface is enormous. All the energy stored in Earth's reserves of coal, oil, and natural gas is matched by the energy from just 20 days of sunshine. Outside Earth's atmosphere, the sun's energy contains about 1,300 watts per square meter. About one-third of this light is reflected back into space, and some is absorbed by the atmosphere (in part causing winds to blow).
By the time it reaches Earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day. Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day.
Maybe one day we'll get around to building a Dyson Sphere, but it sure looks like there's a lot of power out there, just waiting for us to figure out the best way of tapping into it!
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