Ten facts about solar thermal power
- Solar thermal power plants are a lot like conventional power plants - with one major difference
Solar thermal power plants, often also called Concentrating Solar Power (CSP) plants, produce electricity in much the same way as conventional power stations. The difference is that they obtain their energy input through concentrated solar radiation, rather than fossil fuels, and then convert it to high-temperature steam or gas to drive a turbine or motor engine. This difference means that no pollutants are emitted in producing the electricity.
- A solar thermal power plant built on about 1% of the surface of the Sahara Desert would be sufficient to satisfy the entire world's electricity demand.
Solar energy arrives on the earth at a maximum power density of about 1 kilowatt per square meter. However, solar "productivity" is limited by certain geographical factors, including cloud cover and atmospheric humidity. In sunny, arid locations, one square kilometer of land can generate as much as 100 gigawatt hours (GWh) of electricity per year using solar thermal technology, enough power for 50,000 households..
- Solar thermal power plants reduce air pollution: The solar energy falling on an area the size of a basketball court is equivalent to 650 barrels of oil a year
…or, in other words, each square meter of CSP concentrator surface is enough to reduce annual consumption of 200 to 300 kilograms (kg) of carbon dioxide. In addition, the "energy payback" time of CSP systems, taking into account the energy expended in their manufacture, is about five months, which compares well with their useful life of approximately 30 to 40 years. Most of the CSP solar field materials can be recycled.
- Solar thermal power is reliable and available when needed most - during peak demand hours
In most developed countries, the peak demand period - during the hottest part of the day, when air conditioners are running in the office and home - coincides with the period of time when the solar thermal power plant is at peak production. In addition, solar thermal power, as predictable and reliable as the sun shining in the desert, is a renewable alternative to natural gas "peakers", as opposed to other forms of renewable energy, which are either baseload or intermittent.
- Solar thermal power plants can be built (relatively) quickly
Solar power plants can generally be built in their entirety within a few years and can follow demand more closely than most conventional power projects. This is primarily because solar plants are built almost entirely with modular, commodity materials and thus have short development and construction times. In contrast, many types of conventional power projects, especially coal and nuclear plants, require long lead times, and this causes significant disparities between the demand and the supply.
- Solar thermal power plants are big - but relative to other types of power plants - they're space efficient
CSP plants seem to use a lot of land, but when looking at electricity output versus total size, they use less land than hydroelectric dams (including the size of the lake behind the dam) or coal plants (including the amount of land required for mining and excavation of the coal). While all power plants require land and have an environmental impact, the best locations for solar power plants are on land, such as deserts, for which there might be few other uses.
- Solar thermal power can be used with energy storage systems or combined with other energy sources to provide all day power
CSP plants can be designed for solar-only or for hybrid operation, as in California where gas-fired boilers provide steam to back-up solar-generated steam. Thermal energy storage systems, including molten salt, can extend the operational time of solar thermal power plants, sometimes with six to 12 hours of storage. In addition, solar thermal power can complement other renewable energy sources, such as wind, which are available during off-peak hours.
- Solar thermal power plants create permanent jobs and are good for the local economy
There are two main reasons why solar thermal power plants offer an economic advantage: (1) they are labor intensive, so they generally create more jobs per dollar invested than conventional electricity generation technologies, and (2) they use primarily indigenous resources, such that most of the energy dollars can be kept at home. Most importantly, there is no need to import the energy source (i.e., sunshine) and spend local funds outside of the region.
- Solar thermal plants produce electricity whose current and future costs are known with certainty
Electricity produced from solar thermal power plants is a fixed-cost generation resource, generally sold through long term (20 or 30 year) power purchase agreements in which the cost to the consumer is known in advance. Additionally, a diversified portfolio of energy sources, including solar thermal, decreases consumers' exposure to market fluctuations, including the volatile cost of natural gas (which solar thermal typically replaces in the portfolio). The reduced demand for natural gas itself will lead to lower prices.
- Solar thermal power can be cheaper than power from fossil fuels when all cost externalities are considered (and even when they're not)
While many of the costs of fossil fuels are well known, others (pollution related health problems, environmental degradation, the impact on national security from relying on foreign energy sources) are indirect and difficult to calculate. These are traditionally external to the pricing system, and are thus often referred to as externalities. According to the Stern Review, published in October 2006 by H.M. Treasury, global warming is the result of colossal market failure, i.e., failure to price fossil fuel's externalities correctly. A corrective pricing mechanism, such as a carbon tax, could lead to renewable energy, such as solar thermal energy, becoming cheaper to the consumer than fossil fuel based energy.
Even without pricing cost externalities, the cost of solar thermal power is going down. Currently, the cost of solar thermal produced energy can be close to 12 cents (US) per k/Wh. However, many economists and investors predict that this price will continuously drop over the next ten years with increased installed capacity, to 6 cents per kW/h, as a result of technological improvements, economies of scale and volume production.