Solar energy pt 1

This is my first diary on Solar energy of many.

In this entry I’ll cover the solar basics, and cover some of the economics.

I’ve seen many, many comparisons of the energy independence issue to the space race. If we could land on the moon, we can certainly overcome this problem, right? Well its not that simple. When it came to landing on the moon, only 34 Apollo Command/Service Modules were built, even fewer Lunar Modules. While still a difficult task to research, design and build these units, the issue was manufacturing them fast enough to meet the ambitious launch schedule – and not so much on making them cheaply and in large quantities.

Which is the problem we face when it comes to energy. We have the technology. We just need the ability to manufacture it in massive quantities and to do it cheaply enough to make a difference. In 2007, the United States had about 1TW (1 terawatt, or 1 trillion watts) of generation capacity. So how do we go about replacing that with renewable energy? Solar is one avenue, for those in the south and southwest.

The best property of solar power is that it matches peak demand so well. Peak demand is largest in the summer months (May through September) where the grid’s power demand increases dramatically over the “base load”, or the amount of power the grid is always demanding. For example, on July 1, 2008, the peak demand in the areas of California controlled by CAISO was 39GW (GW = 1 billion watts) at around 5PM local time, and the base load was 24GW. So not only is solar power fuel-cost free, it also generates the most expensive power – peak power. Wholesale rates can approach $340/MWh (34c/kWh) during the highest period of demands in California, and even $130/MWh during summer peak periods, whereas off-peak power can cost as little as $35/MWh (3.5c/kWh).

On to the technology…

There are two general forms of solar power – PV or photovoltaic, which converts energy from photons directly into energy, and thermal, which uses the sun’s heat, concentrated to heat liquids to transfer that heat, boil water and turn a turbine. There are variations on these themes, such as concentrated PV, where a lens can focus more sunlight onto a PV cell, and Stirling-engine based solar thermal which uses a Stirling engine to generate the power through a large temperature gradient (e.g. concentrated sunlight and ambient air temperature).

Traditional PV solar modules (or panels) come in a range of sizes and power ratings. Some of the most recent advances include a 224 Watt panel from Sharp, and a double sided solar panel from Sanyo useful for carports and other elevated installations that can produce up to 215 Watts. SunPower Corp. has even announced a 300W solar panel that measures the same 3.5’ by 5’ industry standard panel size.

The problem is that a PV panel is expensive, about $4/Watt. After other factors like additional parts needed – like inverters to convert the DC energy the panel puts out into AC energy your appliances use, and a new power meter than can spin backwards to track your production – and installation of the panels, the cost of the entire system will be about $7-8/Watt. At this price, a reasonable 5kW system that you might install on your roof is about $35,000-40,000, though the cost can be reduced through various rebates and tax incentives. In a sunny environment like my hometown of Las Vegas, the system would pay for itself in about 12-15 years after rebates, the cost of the loan and escalating energy prices.

So you can see that a rooftop PV system is fairly expensive. Even large-scale PV systems on the order of MWs (Megawatts, or millions of watts) are in the same $7/Watt price range.

Solar thermal is also expensive as well, though less expensive than PV-based solar power. The Mojave Desert in the southwest is home to the largest solar thermal system in the United States, SEGS or Solar Energy Generation System, which has a total capacity of 354MW. The most recent solar thermal installation is Nevada Solar One at 64MW and was constructed for about $266M, or just over $4/Watt. Of course, you cant put one of these systems on your roof, and to make the project sufficiently cost effective you’ll need a large swath of land to build on. Finally, solar thermal can also address the biggest problem with solar – it only works when the sun shines. There are projects to store the thermal energy in various heat transfer mechanisms (molten salt) to provide for power generation after the sun sets, until about midnight.

Which brings me to the next point – late last month, the BLM put all solar projects on hold in lieu of a Programmatic EIS (Environmental Impact Survey) to asses the environmental impacts of large scale solar impacts on the desert. Well early this week, they reversed course and said they wlll continue to accept and process applications. Now whether or not its just words on paper or if they really intend to process these applications wont be known for a while since they take so long to process in the first place.

So I think that’s enough for part 1. I went over the costs and the technology. Next I’ll talk about what gets me interested in solar – what developments are coming down the pike, for traditional PV, thermal, and thin-film technologies. And what problems and opportunities those developments unlock. After that, what it could mean for transportation technologies.

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