By Jason Deign
Abengoa, perhaps best known for massive solar thermal plant such as Solana and Mojave, is pitching standalone molten salt storage systems and solar generation-connected thermal storage as a replacement for gas peakers.
The multinational infrastructure developer is already marketing standalone storage projects in the US, Abengoa confirmed in an interview with Energy Storage Report in the run-up to Energy Storage USA 2015 next week.
“Given the experience we have with existing plants [Solana has six hours of molten salt storage], thermal standalone storage is already at commercialisation stage,” said Amparo Pazos Cousillas, director of sales and marketing for Abengoa Solar in the US.
“We are confident in the design and engineering.”
The company said it will continue to gain experience in managing large storage installations with projects currently under construction.
Thus, for example, in Chile Abengoa is building a 110MW solar tower thermal plant with 17.5 hours of molten salt storage that also features 100MW of PV arrays and batteries for round-the-clock generation.
In the US the company is focusing on what it calls ‘flexible renewable energy on demand’, which allows it to fully decouple the collection and delivery of solar energy by adding thermal energy storage.
Given the availability of cheap base-load generation, in the US the focus is not so much on round-the-clock power supply but more on covering peaking needs.
“We are technology agnostic,” said Pazos. “We try to design plants that offer the best match to each market.”
For US markets such as New York or PJM Interconnection, solar thermal plants are clearly out of the question. But Abengoa believes storage on its own could still be a cost-effective capacity option.
Long-term storage characteristics
Molten salt essentially has similar long-term storage characteristics to pumped hydro or compressed air energy stores, but is not subject to the same geographical constraints.
Molten salt also beats batteries on cost for large-scale, long-duration storage deployments needed for energy shifting.
Clearly, the efficiency of molten salt storage is greatest when combined with solar thermal power because the renewable technology delivers heat directly to the storage system, rather than electricity.
But Pazos says the energy to heat up the salt could equally come from excess renewable energy that is currently curtailed.
“Since there is excess at certain times, we could charge the system when the energy cost is zero or even negative, and sell it later on,” Pazos said.
Solar peakers for the US market
Where possible, though, Abengoa will continue to push for solar thermal-plus-storage projects, redefining them as ‘solar peakers’ for the US market. “That’s what we are betting on for the US market,” said Pazos.
While the response from potential customers has so far been positive, she said, Abengoa faces a challenge because the minimum economical size of its plants precludes the possibility of small-scale pilots much beloved by utilities nowadays.
As the Atacama 1 plant in Chile shows, Abengoa is not averse to using batteries. However, the company recognises that it faces strong competition in the battery market, whereas there are few competitors for molten salt.
Nevertheless, Pazos confirmed Abengoa is also currently bidding for battery projects in the US. “We don’t have any problem with it,” Pazos said. “We are just looking for a sustainable future by contributing with sustainable solutions.
“We are equally happy offering molten salt, batteries or flywheels. Our aim is to be an important storage player just as we are an important solar thermal leader.”