Mark Mehos describes solar power towers

The newly launched tower in Spain has over 1,200 mounted mirrors that follow the sun’s path throughout the day. The heat energy from the sun powers a steam turbine to generate electricity, and can be stored for later use, says Mehos.

In the spring of 2009, the world’s biggest solar power tower – one that helps convert sunlight into electricity – launched operations near Seville, Spain. Mark Mehos, an expert in a technology called Concentrating Solar Power – or CSP – works at the National Renewable Energy Laboratory. He described the futuristic design of a solar power tower.

Mark Mehos: Imagine a scaffolding, a hundred meters high, that has a black circular receiver on top of that. Imagine around that central receiver you have a field of mirrors, flat mirrors, all of those mirrors basically pointing at this central receiver on top of this tall tower.

The newly launched tower in Spain, called PS20, has over 1,200 mounted mirrors that follow the sun’s path throughout the day.

Mark Mehos: You can imagine the sunlight striking these mirrors, redirecting that sunlight to this tall tower.

Mehos said the sunlight forms an intense white beam between the mirrors and the tower, and creates very high temperatures at the central receiver.

Mark Mehos: That’s the sunlight, the radiation, transferring before it’s converted into thermal energy.

This thermal energy – or heat – powers a steam turbine in order to generate electricity. The thermal energy can be stored for later use. Mehos said the solar industry continues to develop better materials and designs to harness the sun’s energy.

The solar power tower is one variation of what’s called Concentrating Solar Power (CSP) technology:

Mark Mehos: Concentrating Solar Power, or what we call CSP, is a technology that takes the energy from the sun, it converts that energy to thermal energy or high temperatures, and takes those high temperatures to run a typical turbine to generate power.

Mehos said solar power tower technology is newer than other types of CSP.

Mark Mehos: Solar power tower technology uses different types of optics. Those are less commercial, although demonstration plants have been built, and we’re seeing more companies start to enter that space.

Abengoa Solar, the company that built the PS20, also operates an earlier commercial plant called PS10, and an experimental, high-temperature plant called Eureka.

Our thanks to:
Mark Mehos is the manager of the Concentrating Solar Power program at the National Renewable Energy Lab (NREL) in Golden, Colorado. His work at NREL is to optimize both the technology and the economics of Concentrating Solar Power. Mehos currently is a participating member of New Mexico Governor Bill Richardson’s Concentrating Solar Power Task Force as well as the Solar Task Force for the Western Governors’ Association Clean and Diversified Energy Initiative.

Lindsay Patterson