Wednesday, November 07, 2007

Australian Town to Run on Solar Power in 2 Years

A sun-drenched town in Australia's north hopes to use only solar power in two years after being chosen as the site for a solar thermal power station.

Remote Cloncurry, which boasts recording Australia's hottest day, would be able to generate electricity on rare cloudy days and at night from the station, which runs off heat stored in graphite blocks.

Solar thermal power differs from photovoltaic panels that make power directly. Instead, 8,000 mirrors will reflect sunlight onto graphite blocks. Water will be pumped through the blocks to generate steam which generates electricity via turbines.

Heat stored in the graphite produces steam well after the sun goes down, allowing electricity generators to keep running at night.
This is the first of many cities to be powered completely by solar.

I need to investigate solar thermal further, but I am intrigued by its ability to store energy in the form of heat allowing it to generate electricity into the night. I would guess that this is much cheaper than adding a battery system to a photovoltaic solar plant. The ability to store energy makes solar thermal electricity much more valuable than its intermittent cousins.
The Queensland state government said on Sunday it would build the A$7 million ($6.5 million), 10-megawatt power station as part of a push to make Cloncurry one of the first towns to rely on solar power alone.

The Queensland government said the station would deliver about 30 million kilowatt hours of electricity a year, enough to power the entire town. It is expected to be running by early 2010.
I am tired of seeing solar and wind plants measured in megawatts, as this just tells you how much it can produce under optimal conditions. Because the sun isn't always shining and the wind isn't always blowing, this makes the number worthless for comparing to other types of power plants such as nuclear or coal. Also, the megawatt number does not take reflect that a plant in a very sunny area will produce more electricity a year than one with less sun.

The better statistic is kWh/year produced which I was glad to see this article included (and hopefully more articles will follow suit). This takes into account how often the sun shines and can be directly compared with coal and nuclear plants (well there is still the issue of intermittency, but that is another matter).

A 10-megawatt power plant that ran at full capacity 100% of the year would generate 87.6 million kWh a year. This plant produces 30 million kWh a year or 34% of that amount. I believe the comparable number for nuclear plants is about 90%.

If I am running the numbers correctly, the electricity from this plant is not much more expensive than coal. The plant produces 30 mil kWh of electricity a year. At 5¢/kWh that would be $1.5 million in revenue a year. If the expenses to run the plant took 1/2 that amount, that would leave $750,000 in profits for a rate of return of over 10% on the $6.5 million investment.

via Reuters


Rebelfish said...

Solar thermals are a fairly common electricity generating form, but I haven't heard of one that just heats up blocks of stone before. Usually there are huge troughs that heat up oil inside that then runs a turbine. Or, as made famous in SimCity2000, the Power Tower has a bunch of mirrors that concentrate sunlight enough to use liquid salt as a working fluid.

These too can produce power for between 3 and 12 hours after the sun goes down, which I'm sure is cheaper than a huge battery. However, the fact that solar produces power during the day is great when it's connected to the grid (tho not so much when it's the only thing powering a town). According to a report by J.B. Lasich and P.J. Verlinden, "in Australia, peak load market is growing 4-times faster than base
load", and un-batteried solar can help with that.

Fat Knowledge said...

Good info, thanks rebelfish.

I am guessing that the peak load is growing in Australia due to greater air conditioning. How ironic is it that we can trap the sun's heat to convert it to electricity to run an air conditioner to decrease the heat from the sun. :)

Post a Comment

Note: Only a member of this blog may post a comment.