Coupling photovoltaics and grid-scale energy storage : performance and sitability

The Fifth Assessment of the International Panel on Climate Change has called for a four fold increase in the use of low-carbon sources of electricity to help stabilize climate change by mid century. Many people look to solar power systems to help reduce carbon intensity, but cost and variability have been significant obstacles to their widespread deployment. However, the cost of photovoltaics has dropped significantly in recent years, and grid-scale energy storage technologies are available to allow for production of dispatchable electricity from photovoltaics. In particular, compressed-air energy storage is both low-cost and can be built in a wide variety of geologies as well as above ground. I show that coupling large-scale photovoltaic arrays and grid-scale storage allows for dispatchable electricity production at costs that are comparable to other low carbon electricity sources. I examine four load curves: base-load generation, on-peak generation, and averaged load curves for the Electric Reliability Council of Texas (ERCOT) and PJM Independent System Operators. I found that on-peak and ERCOT loads typically required the lowest amount of storage, up to 2000 MWh [subscript e] less than that for base-load generation. However, in some regions, and for some storage amounts, baseload output actually provided the lowest cost of electricity. I also show that such coupled systems could provide base-load electricity for ≤ 0.08/kWh [subscript e] on more than 40% of global land surface, with a capacity factor equivalent to that of the US nuclear fleet. Importantly, this is below the projected cost of electricity from new nuclear power systems. While cost is a major factor, also of importance is where systems of photovoltaics and grid-scale storage would provide the most benefit. Locations expected to provide energy at the lowest cost do not necessarily correspond to load and population centers, where the electricity is most needed. I use multi-criteria decision analysis techniques to perform a global study of the optimal locations for siting these coupled systems to maximize their social benefit. I found that the most ideal locations are generally located in Africa, Iraq, and southeast Asia, as these locations have both high irradiance levels as well as expanding populations and low grid connectivity.