Khi Solar One construction works in August 2014. Image: Abengoa.

By Jason Deign

CSP construction safety is under the spotlight following the industry’s biggest tragedy to date.

At 1.30pm local time on Monday November 3, one of the cranes involved in the construction of Abengoa’s Khi Solar One power tower near Upington, South Africa, crashed to the ground, killing two workers and injuring seven.

The workers, who “all belonged to companies carrying out work for Abengoa,” were “immediately taken to the nearest hospitals,” said the Spanish CSP developer’s press office in a written statement for CSP Today.

“Of the seven wounded, six have already been discharged and one remains under observation and is progressing well,” says the statement. “Abengoa wishes to express its deepest sense of regret for the loss of the workers, along with its sympathy and support for the families"

“It also wishes to express its support for the wounded up until their complete recovery. As soon as it was known, the pertinent local authorities were quickly informed and the company has made itself completely available to help and collaborate in any way needed.”

Although Abengoa did not comment further on safety matters, it seems reasonable to assume the company will be reviewing health and safety protocols at Khi Solar One in the wake of the contractor fatalities.

Meanwhile the question for the industry is whether safety protocols need to be reviewed in general.

So far, the industry has maintained a remarkably good record on building site health and safety, despite recruiting vast numbers of workers for plant construction, including up to 2,650 at the world’s largest project, Ivanpah.

Serious accidents

According to published reports, there only appears to have been a single construction worker fatality until now: in 2011, during the construction of the Andasol 3 plant in Spain, a metal gate crushed a tractor driver. Serious accidents have also been mercifully rare.

In 2008, 64-year-old Sebastián Pérez was badly injured on the building site for Iberdrola’s Puertollano CSP plant. In 2010, six workers suffered burns in a molten salt spill at the La Dehesa plant. And in 2012 a worker at Abengoa’s Solaben II project sustained a head injury.

CSP operations and maintenance (O&M) has also been relatively incident-free to date. The main concern in O&M is about the fire hazard arising from the synthetic-oil heat transfer fluids used in many plants.

But despite incidents such as a Therminol heat-transfer fluid tank explosion at the Solar Energy Generating Systems II plant in Daggett, California, no deaths seem to have been reported.

That makes the Khi Solar One accident, the most serious on record for the industry so far, all the more tragic.

While mortality rates for CSP energy production are hard to come by, a rough calculation of annual output based on the 2013 global installed base of 3.5GW and a capacity factor of 33%, as stated for the Ivanpah plant, yields a current death rate of around 0.19 per terawatt-hour.

This compares to published figures of 280 for Chinese coal production, 36 for oil, 24 for biomass, 4 for natural gas, 1.4 for hydro, 0.44 for rooftop PV and 0.15 for wind.

Additionally, says Stephen Tordoff of Energy Canvas, a consultancy with renewable energy project experience in South Africa: “I would look at the mining sector and relate how the mining sector performs in health and safety.”

Worker safety

The comparison helps put the Khi Solar One accident in context, as dozens of miners have perished already in South Africa so far this year. Nevertheless, that should not be cause for the industry to let up its guard regarding worker safety.

Other renewable energy sectors have had to confront growing numbers of safety-related incidents in line with their industry growth.

The wind industry, to take one example, has worked hard to counter worker hazards, and in Spain now boasts an accident rate comparable to working in an office. One of the key developments there has been recognition of the importance of training for working at heights.

In most CSP plants, such training is not relevant. But as power towers such as Khi Solar One become more popular, perhaps this is sort of thing that should be incorporated into everyday safety training.

For now, though, it remains unclear whether such precautions could have saved lives at Upington.

As Luis Crespo, president of the European Solar Thermal Electricity Association, says regarding CSP: “When you are working at height with large masses, regrettably you have to expect these things.

“This was a problem with an item of civil engineering equipment, an accident such as one that could have happened on any building site.”