 |
|
|
||||||||||
|
||||||||||||
 |
||||||||||||
|
|
 |
|
|
|
Return to Solar ponds home page Comparison of solar pond generated power with some alternative energy systems
There are two parts to the cost of power.
To get a realistic comparison between methods with a high running cost and those with a high capital cost, the capital cost needs to be spread over the annual production. A common way to do this is to treat it as if you have borrowed the money at the going interest rate (we have used 7%) and you must 'repay ' this each year to keep the system going. (There are more sophisticated methods , but this is simple enough to see how it works)
This has to be our base line because most power in Australia is produced by coal fired power stations. The wholesale price of coal fired power in South Australia (as at December 2006) is 4c per kWh, (or $40 / MWh) - this is a commercial rate so it includes the cost of fuel and the cost of capital as well as part of the cost of distrubution. The retail price is around 15-18c per kWh.($150-$180MWh) - depending on your contract Peak (spot) power prices in mid summer can be as high as $4000 per kWh (100x the regular price) Cost per unit of power is $0.04
Electricity produced by a 1ha solar pond is 50kW continous 24hours a day 365 days a year. This adds up to 440,000kWh in a year. The running cost is around $10,000 per year. An investment of $1million costs $70,000 per year making total cost per year of $80,000. The cost of power is $0.18 per kWh. Capital invested is $20,000 per peak kW installed but in this case peak power and average are the same. The difference between average power produced and peak power is important because systems like photovoltaic (solar) cells only produce at peak power in the middle of the day in the middle of summer. Average power production from a wind or photovoltaic system is far less than peak production because photovoltaic produces nothing at night and wind produces nothing if the wind does not blow. Costs do not alter much with the pond size. This power rating is conservative and in the sunny parts of the South Australia (eg where there are at least 250 rain free days) such a pond should deliver this power output day and night through summer and winter. A large solar pond averages the energy it receives from the sun over about six weeks and can deliver power at that average night and day and through quite long periods of overcast weather.. Solar ponds can increase output in summer but the difference is not great. For the purposes of this web site solar pond output is calculated for the mid winter rate. Huge areas of South Australia (and Western Australia, NSW, VICTORIA, and - in another 50 years, Queensland ) are subject to dryland salinity and therefore have massive resources of saline water redering land useless for agriculture. Where these areas correspond with many sunny days per year, and poor wind resources,then solar ponds are the obvious choice.
Many sites are ideally suited to wind power with over of 200 days of wind of a velocity suitable for generating power. Even in these sites, it is expected that the system would only function 60% of the time. Modern wind generators (as at 2006) are 2MW peak capacity and cost $1m per generator with an additional $1m to install. Allowing for the 40% down time - this will produce 10,500,000kWh of power in a year. Running cost is small , capital cost is $140,000 per year So power cost is $0.02 per kWh - for a GOOD wind location.
A 'house sized' installation using 'grid connect' technology (ie no batteries) of 2.4kW costs $25,000 . This would normally yield power only in daylight hours with an average output of around 3500 kWh / yr. Running cost are minimal and 'cost of capital' is $1750 So cost of power is $0.50 /kWh ($500/MWh). (This does NOT inlude subsidies of around %0% of the costs )subsidy of $7000, and some power compaies offer more subsidy) or This price is doubled for a stand alone unit using batteries to supply power for after dark. This method does have the advantage of 'install and forget' - essentially zero maintenance (except for batteries).
This is the common 'remote area' power supply. It is high maintenance method but highly portable. 20kW unit costs about $20,000 so annual cost is $1400 to produce 175,200kwh per year. Cost of running is 35c per kWh in fuel but cost of maintenance needs to be included - many users claim an additional 20c/kWh cost of power$0.55 per kWh Return to Solar ponds home page
|
|
|
|
[index] [solarlinks] [compare] [HISTORY] [saline] [ro] [moreinfo] [history] [costs] |