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Sunday, September 14, 2014

Solar Thermal Electricity Plant in Spain

PS10 solar power plant, Seville, Spain
PS10 solar power plant, Seville, Spain
Tony Windsor recently wrote an article "No guts, no glory on clean energy" about the Abbott Government leading Australia backwards on clean energy.

Further to the statement, "In 2011, Tony Windsor spent some time in Spain with Ross Garnaut, visiting a solar thermal electricity plant that uses molten salts to store heat so that power generation can take place at night or on bleak days", a modified version of this Spanish solar thermal electricity plant with energy storage is more economic.

The design may not be to everyone's liking but it serves an essential purpose.

At present the coal industry is desperate to maintain market share against inroads by renewable energy, natural gas and nuclear energy.

The coal industry is deliberately increasing production of coal to drive down the price. This helps to keep competitors out of the energy market.

The coal industry also has the capacity to pay financial inducements to "buy" government decisions to build new coal-fired power stations.

It can afford to lose money on this strategy for a number of years. This is because every new coal-fired power plant will operate for at least 40 years.

In the past decade a whopping 734 gigawatts of NEW coal-fired generating capacity has been built world-wide.

It is essential to provide a financially superior large-scale power plant design to place in front of every decision-maker before they commit to constructing any more coal power plants. This may not be "ideal" but it is pragmatic.

The capital cost of the Spanish solar thermal electricity plant can be reduced by almost seven-eighths:
  1. A solar thermal plant (and coal power plants) only operate at about 30 percent thermal efficiency.
  2. Solar thermal energy is available on average for about 6 hours a day.
  3. To use solar thermal energy for 24 hours a day, the area of heliostats must be 4 times greater than what is needed for operation for 6 hours. The additional heliostats are needed to add thermal energy to a molten salt heat bank.
  4. If the efficiency of the power plant is doubled to 60 percent then the area of heliostats may be halved.

So, how to double efficiency and collect solar thermal energy for only 6 hours - and be able to reliably generate electricity for 24 hours a day, 365 days a year? (Note this cuts the area of heliostats and their capital cost and maintenance cost to just one-eighth of the Spanish solar thermal electricity plant.)

The way to do this is to use the solar thermal energy to convert coal and waste biomass to gas, then use the gas to generate power in a combined-cycle gas turbine power station. These can achieve 60 percent efficiency.

The amount of coal used in this process is three-eighths of what a coal power would use: solar energy provides all the energy needed for 6 hours out of every 24. The efficiency is double what a coal power plant could achieve, so only half as much coal is used in the remaining 18 hours of each days' electricity generation.