Saudi Arabia and Japanese SoftBank have signed a non-binding Memorandum of Understanding to build the world’s largest photo-voltaic (PV) solar project by 2030. The project will comprise a total investment of US$200Bn to create a generator capacity of 200GW, tripling Saudi Arabia’s current energy production.
This compares with the world’s largest current installed solar project, the Longyangxia Dam Solar Park in China with 0.85GW, around 200 times smaller than the proposed Saudi project. The project would also be about 100 times larger than the next biggest planned solar project, the Australian Bulli Creek farm, and more than double what the global photovoltaic industry supplied last year according to BNEF.
A fundamental characteristic of the Saudi project will be construction of ‘the largest utility-scale battery’ in two to three years that will supply ‘evening hour’ power to consumers, said SoftBank’s founder.
Roskill view: Beyond the large size of the project, not much attention has been paid to the details of the possible battery technology.
While some lithium-ion batteries will surely be deployed for power quality and bridging power purposes, bulk energy storage for longer energy supply duration will, however, use other technologies. It is important to highlight that, as of today, lithium-ion batteries applied to ‘utility-scale’ energy storage can only supply energy for periods ranging from seconds to several minutes (with of course some smaller-scale lithium-ion batteries being adapted as residential and commercial long-duration storage).
The key point of the Saudi deal is that the project intends to supply ‘evening power’, when the solar PV panels won’t be effective after sunset. This will require longer duration storage technologies able to supply large amounts of power for several hours. For this purpose, thermal storage systems such as molten salts are the best-suited technology today, given the fact that they can cycle without losing storage capacity for almost three decades. Molten salt systems, however, can only work with concentrated-solar-power plants (CSP) – those using computer-controlled mirrors to reflect the sun towards a tower – as opposed to the photovoltaic systems proposed in the Saudi Arabia and SoftBank deal.
Lithium-ion technology is developing fast, in terms of cost but also energy density and cycle life, with some research suggesting that LTO batteries (lithium–titanate or lithium titanium oxide) could withstand more than 30,000 cycles by 2030. By then, even solid-state batteries may be available, changing the economics and amortisation of thermal storage systems. Speculation over the batteries used for this solar project will likely continue in the coming years, until more details are disclosed by both parties.