Examining the solar tower solution

Shutterstock.com/ SSSCCC

There is no need to convince you of the benefits of solar power over fossil fuels. Investment in solar power is increasing dramatically as people are now realizing that fossil fuels are a solution that will soon fall to the waste side. Countries are now looking for different ways to embrace solar power in an efficient manner. One area that is being looked at in more detail is the solar tower.

A solar tower is a simple structure in theory. Instead of individual solar panels processing power, the complexity is held in a single tower. Panels are used as basic mirrors and have one job, to direct sunlight towards the large tower head. This means that the panels only have to be fitted with a two-axis control system. This will allow them to move up and down and side to side to alter their position to better push sunlight towards the tower. This is seen as a lower-cost alternative than having every solar panel having the complex task of generating power.

The solar tower than uses that sunlight to heat water and salt, creating steam. The steam is used to move a turbine and create electricity. The idea is simple in theory but it was first thought of in 1979 and has not taken off yet. It does have some challenges.

One challenge is the impact on bird life in the area. If birds fly between the beam of sunlight that is being transmitted they can be killed. The sunbeams can be over 500 degrees celsius and would easily kill anything that stepped in the way. While some have suggested that for this reason the number of panels should be reduced, this greatly lowers the value of each solar tower. A different solution such as audio signaling may need to be used to deter the birds from approaching.

Another challenge is the dust that settles on the panels. These need to be cleaned regularly. The panels could be fitted with a cleaning device but this means each would require more complexity and power. Unless these requirements can be kept to a minimum the costs start to outweigh the benefits.

That appears to be what has happened to many of the solar towers that have been tried and tested. Cost is the greatest challenge. In 1982 the first commercial solar tower was built in America but it was shut down by 1988. It was deemed too inefficient. It was altered for a second project but it was shut down in 1999 for similar cost reasons. Six solar towers have been started and shut since the idea first came to pass. This shows that it is not as simple a solution as it appears. 

In Europe, Africa, and the Middle East, there is more success. There are examples from Spain, Germany, Morocco, and Israel where solar towers are still being employed. Some suggest that the landscape and climate are more suitable in these places. In 2013 Chile made the bold plan of switching from its reliance on coal power to solar power by introducing a solar tower. $1.3 billion was invested in the project but it took to long to complete. By the time the project was almost ready it been outpaced by cheaper alternative solutions. The price that it would have been able to charge for power was now too high and the project was removed. 

Solar towers are a clever way to solve the energy crisis. However, they are not as simple as they appear. More work is required to create a solution that is cost-effective and viable for the long term future.