By Jason Deign

In a project as large as BrightSource you could reasonably expect delays as a result of anything from financing to industrial action. But since its inception, the world’s largest CSP plant has had to contend with potential holdups from a wholly unexpected quarter: desert critters.

Before the project was even out of its planning stage, BrightSource had to cut output by 10% and reduce its footprint by 12%, slashing the number of power towers from seven to three, to allay fears over the impact the plant would have on the desert tortoise, a vulnerable species.

After construction began, as it became apparent that the tortoise population had been underestimated in initial surveys, the company had to shell out increasing amounts in mitigation efforts, at one point employing as many as 100 biologists.

BrightSource currently estimates it has spent approximately USD$22 million on a care programme for tortoises, along with a further $34 million on restoring habitats, building fences and buying 7,164 acres of conservation habitat, twice the area of the plant.

As if that were not enough animal-induced anguish, in April this year five pairs of red-tailed hawks were discovered nesting in the path of a proposed transmission line upgrade for the plant.

Although the species is classified as of ‘least concern’, there is a requirement to avoid nesting sites by at least 400 feet, which meant the upgrade was off limits until the end of the nesting season last month.

While BrightSource has been at pains to emphasise that none of these issues has resulted in delays to its schedule, they clearly highlight the danger of assuming that the large empty spaces traditionally used for CSP are in fact as empty as they seem. 

In Spain, for example, Dr Octavio Infante, SEO/Birdlife conservation area technician, says the areas used for CSP developments are often “steppe zones inhabited by bustards and sandgrouse. In Castile-La Mancha they are on imperial eagle feeding grounds.”

Resting areas

In Estremadura, the other Spanish province surveyed extensively by SEO/Birdlife, CSP plants occupy flatlands formerly used as resting areas by migrating cranes.

All this is something of a pity given that CSP is generally viewed as a fairly benign form of energy generation. Unlike fossil fuel, it does not spew out immense amounts of planet-heating carbon. Nor does it kill animals through direct impact, as is the case with some wind turbines.

If you are looking for ways in which CSP does have a negative environmental impact, says Bloomberg New Energy Finance CSP analyst Andrew Stiel: “One of the key considerations is water.

“It is unfortunate that, unless you go for a dry-cooling system, solar thermal plants place a large demand on water resources in areas where water is likely to be scarce.”

However, he adds: “In the States they seem to be going for dry cooling systems anyway, which largely mitigates the environmental impact.”

Another potential impact is the spillage of oil from burst receiver tubes, which has already happened in at a couple of plants worldwide, says Stiel.

But these were largely the result of teething problems with the technology, he says: “I see instances like this as progression along the learning-curve. With experience, the weak spots in a plant will be identified and improved.”

That basically leaves habitat destruction as the main environmental issue associated with CSP.

Species diversity

While it is true that plants tend to occupy habitats with low levels of species diversity, it is equally the case that land given over to CSP cannot usually be shared with its original inhabitants, and the areas involved could potentially be quite significant.

To avoid possible conflicts between developers and pressure groups, Infante advocates a generally more rigorous approach to environmental surveys.

At BrightSource, for example, the tortoise population was underestimated because surveys were carried out in unusually dry weather, when the animals tend to bury themselves out of sight.

This might have been picked up if surveys had been carried on for longer, and Infante says checks should be sustained for at least a year to make sure all animal breeding and migrating patterns are accounted for.

At the same time, he believes, CSP developers should carry out environmental surveys on a range of sites before making a final land purchase decision, rather than buying a site and then cutting corners to get project approval.

He adds that it would be wise for developers to play it safe and stick to land that is of little or no scientific interest, of which there is plenty.

To respond to this article, please write to Jason Deign

Or write to the editor, Jennifer Muirhead