Student develops solar energy storage device

Claus Volkening's working model of a solar updraft tower uses water storage tanks to solve the problem of existing solar power plants that only generate electricity when the sun shines.

He said: 'The problem with existing solar power generators is that the times of peak generation of energy - during the day - do not match with times of peak need at night.

'I wanted to find a way of generating solar power at night and found that by using water tanks to store the Sun's energy through the day I could smooth out the energy available from a solar power plant.

'With my model, even when night falls and temperatures drop electricity is still available and reliable,' he added.

Volkening's scale model is based on a 1km-high tower surrounded by glass or plastic above water tanks across a 16km square area to recreate a greenhouse effect.

Existing solar updraft towers work by collecting heat energy from the sun and sending the warm air up through the tower, which houses a turbine.

When the turbine turns it generates electricity as long as the sun shines with zero harmful emissions.

Volkening said: 'After sunset, the updraft drops and the energy output effectively stops.

'In my model, some of the solar energy is removed from the airflow process to heat the water and this is then released at night.

'This avoids a peak during the day and smoothes the overall output,' he added.

By using water to store some of the heat the amount of electricity generated at various times of the day or night can be changed by adding or removing water tanks.