International technology and infrastructure group Abengoa, which has developed a portfolio of three concentrated solar power (CSP) projects in South Africa, believes blending CSP with solar photovoltaic (PV) technology is the logical next step for lowering CSP costs, while also producing dispatchable solar power.
XiNa, which means ‘bright light’ in the Khoisan language of Nama-Damara, is located close to Abengoa’s 100 MW Kaxu Solar One parabolic-trough power station, which has been operating since 2015. The group’s 50 MW Khi Solar One solar-tower plant, which is located near Upington, began producing in 2016.
Abengoa South Africa business development VP Dominic Goncalves tells Engineering News Online that the group remains optimistic about the future of CSP, despite criticism of the technology’s costs and recent delays to South Africa’s renewable-energy procurement programme.
However, building hybrid plants, which incorporate both solar technologies, could assist in reducing costs even further. Such an approach is already being pursued in Morocco, where low-cost PV plants will be used during the day, while the solar-thermal power produced using CSP is stored in tanks for release to the steam generators at night, or when there is insufficient solar radiation for PV generation during the day.
All three of Abengoa’s South African plants already include molten-salt storage capacity, with the R9.5-billion XiNa incorporating five-and-a-half hours of storage, enabling the plant to supply into the grid during the evening peak from 16:30 to 21:30.
In fact, XiNa’s power purchase agreement (PPA) with Eskom includes an incentive for peak-time production. For the period from April 2018 to March 2019, the standard-time tariff is set at R2 151.28/MWh, while the peak-time tariff is R5 808.47/MWh.
“Technically it’s now feasible to have solar thermal technology like XiNa being dispatchable almost 24 hours a day, although this will require an oversized configuration of the storage technology at an increased cost.”
However, the future of South Africa’s energy mix will depend primarily on the outcome of a review of the country’s Integrated Resource Plan (IRP) for electricity, which Energy Minister Jeff Radebe has confirmed is currently under way.
“The Department of Energy is at an advanced stage of finalising the review of IRP, which will provide further policy certainty on electricity generation infrastructure for the next 20 to 30 years,” Radebe said at the recent Japan–Africa Public Private Economic Forum, which took place in Johannesburg.
Despite a recent protracted delay in South Africa’s roll-out of renewable energy, Goncalves confirms that Abengoa is “more than willing” to participate in new projects, adding that the group has been encouraged by the recent revival of the Renewable Energy Independent Power Producer Procurement Programme and the signing of PPAs for 27 delayed projects.
Such an environment is not only necessary for attracting renewable-energy investment, but also the other possible public-private investment areas in which Abengoa is keen to participate, such as the proposed gas-to-power programme and possible desalination projects.
By: Terence Creamer
Creamer Media Editor