Areva’s Compact Linear Fresnel Reflector Technology

At its power plant along Interstate 10 on the south side, Tucson Electric Power Co. is dismantling a massive old fuel-oil storage tank to make room for a promising renewable-energy project.

The work, visible from the freeway, could be seen as a symbol of the shift from fossil fuels to renewable energy – but it’s really an object lesson in how they can work together.

TEP is dismantling a fuel-oil storage facility no longer in use at the mainly coal-fired H. Wilson Sundt Generating Station to make room for a proposed project with Areva Solar that would be among the first to use concentrating solar thermal power technology to augment steam generation at the plant.

TEP hasn’t widely publicized its project with the renewable-energy subsidiary of French energy giant Areva, since the companies have yet to finalize a deal.

But TEP described the 5-megawatt project as part of its 2012 renewable-energy buildout plan, which was approved by the Arizona Corporation Commission last week.

The company got the go-ahead to proceed with the $7.8 million project, though it was unable to gain approval for upfront funding.

While concentrating solar thermal power plants aren’t new, the Areva plant will be the first in the world to take a new kind of solar steam-generating technology and hook it up to an existing fossil-fuel power plant’s steam turbine.

Areva’s Compact Linear Fresnel Reflector technology uses mirrors to concentrate sunlight to directly create steam power.

But rather than using trough- or dish-shaped mirrors common to other concentrating solar systems, Areva’s technology uses a system of nearly flat mirrors, arranged in louverlike arrays and motorized to track the sun, to heat up water passing overhead through a linear absorber.

The Areva system also is designed to heat water directly, compared with other systems that generate steam indirectly with heat-transfer fluids such as oil or molten salt.

Areva acquired the reflector technology, pioneered in Australia, in 2010 when it bought California-based Ausra Inc. The technology is used in a 5MW stand-alone solar plant in Bakersfield and is being added to provide 44 megawatts of new steam power to CS Energy’s coal-fired Kogan Creek power plant in Queensland, Australia.

In comments before the Corporation Commission last week, an Areva Solar official said the company’s system is one of the most cost-effective solar technologies for large-scale generation, cutting the use of thousands of tons of coal and reducing related greenhouse gases.

The technology can be installed on existing steam plants for $1.60 to $1.70 per watt, with no new transmission interconnections, John Robbins of Areva Solar told the commission.

By comparison, rooftop solar photovoltaic installations are running about $4 to $5 per installed watt.

"Arizona has a very unique opportunity, with the coal generation you have, to take advantage of solar steam augmentation," Robbins said.

Carmine Tilghman, TEP director of renewable energy resources, said the use of Areva’s technology at the Sundt plant is a good deal for TEP and its ratepayers.

"That’s what makes these projects so attractive – you basically cut off half the cost of a CSP (concentrating solar power) facility by attaching it to an existing steam plant," Tilghman told the Corporation Commission.

Under the current proposal, Areva would build the plant in the next year and operate it for a year at no cost to TEP, Tilghman said. If it doesn’t work, Areva would pay to remove the installation, he said.

A TEP spokesman said the company remains committed to the project, but officials were still reviewing the effects of the regulators’ decision to delay TEP’s cost recovery.

But if the project becomes a reality, it will be another example of leading-edge solar technology development in Arizona.