Pluses and Minuses of Solar Thermal Compared to Coal and Nuclear
A recent paper sums up the advantages and disadvantages of solar thermal compared to nuclear and coal as follows.
“Access to a much larger practical resource than wind or nuclear, variously estimated at around 30 times current human commercial energy use (total solar energy received is about 5000 times human energy use, but many locations cannot be used). For Australia, the current electricity generation would require about 1300 km2 of land, a square about 36 km on a side. This is about 1/36th the size of the largest Australian cattle station, Anne Creek.. Around each of Moree and Cobar, there are about 40,000 km2 of suitable land, and there are many other potential sites around Australia. There is clearly no resource issue for sustainable use, now or in the future.
STE (Solar Thermal Energy) can use low cost energy storage in thermal reservoirs. The first (oil storage) was successfully commercially demonstrated in the mid 1980’s (Frier and Cable, 1999) and the second (molten salt) is being commercialised in parabolic trough plants in Spain (Andasol, 2004). SHP is developing very low cost pressurised water storage, expected to be commercialised later in this decade. Lloyd Energy in NSW is close to building the first graphite storage system for a commercial solar plant, and Germany is developing concrete storage. Storage actually drops cost by reducing the size of turbine required.
Like wind, there are no waste issues of significance and the technology is very safe.
Unlike both wind and nuclear, local inland communities are almost universally attracted to such solar plants for local job creation and low environmental impact.
Like wind, long term immunity from fuel cost rises, since no fuel is used.
High availability( assumed to be 94% in this paper).
Capital cost is mostly upfront, higher than coal-fired plant, and close to nuclear plant of similar annual output. [see note below]
The solar resource varies during the day according to weather conditions, and completely disappears at night, necessitating the use of storage. Storage systems other than molten salt and thermal oil still need to be proven on a large commercial scale.
The availability of solar energy drops in winter, so that unless the system is designed for the summer load, it cannot supply the whole of the winter load; seasonal storage at high temperature is not possible except with chemical change systems like ammonia and hydrogen, using very large tanks.