World's Largest Solar Power Tower Commissioned

It seems like a heck of a lot of space for 20 MW. I know that we love projects on a grand scale but what about the tens of millions of acres of flat, un-obstructed roof tops in the world for solar arrays? If the government took the energy crisis seriously, the legal concept of eminent domain could be used to take advantage of these roof tops.

Thats a lot of space ! Any light on the maintenance involved in running the plant ?

Despite others comments, I think this has to be seen as an experiment at a demonstrably viable scale. One of my personal concerns is that the focus point, being some 400ft+ must be visible for many miles, and must be at least as bright as the sun itself. Apart from the possible danger to peoples' vision is an incredibly bright spot on the horizon what is wanted.

Being a great afficianado of SCP, I'm still of the opinion that Ausra have the best SCP solution at the moment with their Fresnel systems. Where I live (England which is latitude 52N) we have little enough light for half the year to mean that energy importation is going to continue for the foreseeable future, whether that be oil (as it is now) or electricity through HVDC lines.

In Europe we're close enough to the Sahara desert (this plant is only a few hundred km North of the Sahara itself) for that to be a viable source.

Our main problem is political, not practical. If we had an Obama over here, then maybe we'd be blazing the trail, but with so many sovereign states that's unbelieveably difficult. The Europeans and Asians will probably have to wait for a tenth of Arizona to be covered with mirrors before the penny will drop over here.

Speaking as a semi-retired electrical / electronic engineer - 59 this year :-( - I'm actually really very optimistic about the energy future. If the experience of mankind's adoption of new technologies is replicated here, I think we'll all be living in an all electric world within 25 years.

The plant runs at a calculated maximum 11.1% efficiency........on a sunny day.
Not being familar with this exact installation, I wonder if it stores any energy to be used when the sun is not shining?

Seems to me that a pv system would be less problematic. But, to each....his own poison I suppose.

I have a nice absolutely 'breakthrough' technology to manufacture very thin multi crystalline silicon pv cells. Individual cells output at about 15% efficiency. My cost for production of 'panels' is projected to be about US$0.65/watt output. www.siliconsolarelectric.com

lkelley@goruby.com

CSP is predictable and with thermal storage largely dispatachable. PV is a good local solution, but acres and acres of flat roof would eventually destablize the grid system with intermittent power. I also agree it seems like a very large field for 20MW. LL

Space use is about 6 acres per megawatt, a little less efficient than parabolic troughs (5 acres), but much more efficient than thin film (8 acres per MW for First Solar). This is an exciting development, but given this is just the second demonstration plant, years of experimentation are still needed to optimize and commercially prove out the real economics. My view is that power towers are not likely to be economically competitive with parabolic trough systems for most power generation purposes. The ability to generate higher concentration (higher temperature) and shorter distance traveled by the HTF does not translate in cheaper power because of the optical inefficiencies of the heliostat field, the cost of the controllers/drives for each mirror and the smaller turbine/generators (20 MWs). However, the design has a lot of beauty.

I would like to know if it would be possible/practicle to create a parabolic (or other)solar application for a home; which would create both heat (for the house in the winter by solar hot water), AND electricity by a steam turbine- the same way commercial applications do?

As a Johnny-come-lately to Fresnel CSP, I had been a great enthusiast for the parabolic trough CSP (and of course still am by comparison with most of the other alternatives). The fresnel system uses essentially flat pieces of glass at knee or shoulder height, and they are all mounted horizontally initially and just rotate to follow the sun (see http://www.ausra.com/technology/howitworks.html). Because all the glass is at the same height you don't get the shadow of one collector interfering with its neighbour (as you do with parabolic). The glass is much, much more inexpensive as it's flat not curved; the glass tips upside down in sand-storms and unlike parabolic doesn't offer a huge 'sail' to the wind.

Heat can be stored in the form of molten salts (or other) for generation of electricity in the dark periods at night. So as they claim it is an alternative to base-load electricity generation such as coal. (But it's much quicker to turn on and off as desired).

As for private generation using parabolic mirrors and a steam generator, I personally would have doubts that it would be cost effective, as such a small generation unit would be very inefficient. I looked at combined heat and power (CHP) a couple of years ago, and the concept of 'micro-CHP' was typically enough heat and power to supply a residential home of 60 people or 15 houses in it's smallest version.

Evacuated tube solar panels, mostly made in China, are astonishingly effective in garnering heat from the sun and are absolutely ideal for heating water if that's the objective. Traditional PV panels are still the only practical way for private electrical generation.

----"PS20 consists of a solar field made up of 1255 heliostats with a surface area of 1291 square feet each."----------

1255 x 1291 = 1,620,205 sq. ft. / 43,560 (sq. ft. acre) = 37.1 acres

------"Not being familar with this exact installation, I wonder if it stores any energy to be used when the sun is not shining?"--------

No mention of whether there is any storage on site, but it does not need to be on site. Electric pumps that pump water back upstream for reuse in hydroelectric generation are commonly used during off peak power generation to store energy. They need not be part of the solar generation site, nor even owned by the solar generation company to be run on solar power. Just because this site does not have an energy storage system as an integral part of the design does not mean that it is not being done. Recirculating pumps don't care if the electricity they run on comes from coal or solar.

According to Wikianswers one ton of coal can generate 2500 Kwh of electricity. Assuming 10 hours per day operational time, 10 X 365 = 3650 hours per year. 3650 X 20 Mw = 7300 Mwh/yr 7300 / 2.5 = 2920 tons per year of coal. I don't know how much land area would be destroyed to strip mine 3000 tons of coal per year, and I'm sure it varies widely, but I'd be willing to place a very large bet that it would take more than 37 acres. Year after year after year.

A few other statistics for this plant.

Total airborne particulates produced (in tons) = 0.

Total fly ash and creosote load production (in tons) = 0

Total sulphur and nitrous oxides released (in tons) = 0

Total amount of greenhouse gasses produced = 0

Total fuel cost per year = 0

Projected increase in fuel price in 10 years = 0

Year afer year after year.