Dave Elliott: Solar energy is on the rise. According to the International Renewable Energy Agency (IRENA) there is over 480 GW of grid-linked solar photovoltaic (PV) capacity worldwide — around 175 GW of it in China alone. With costs for PV solar falling dramatically — 76% since 2009 — more is planned. Indeed, the consultancy DNV-GL says that solar power could have a 40% share of total global electricity generation by 2050 while Shell projects solar supplying 32% of total global energy by 2070. Yet there are limits to PV solar deployment on land. Roof space in urban environments may not be sufficient to deliver enough power for a city. There could also be land-use constraints of solar farms in rural areas. In this case, looking at the use of floating PV arrays on reservoirs and lakes or even at sea could be attractive. LUT University in Finland has suggested that there could be 4.4 TW of floating PV on hydro plant reservoirs even if only 25% of the area of the reservoirs of the current 1.2 TW of current hydro plants was used. That could generate 6270 TWh — well over twice the output available from hydro (2500 TWh), which accounts for about 16% of global electricity at present. When available, the PV output could be fed direct to the grid and when not, hydro power could be used. LUT adds that if non-hydro reservoirs were also used, the PV output would then be over three times that of hydro globally. It’s a bold ambition and even if that is a wild overestimate, it certainly seems like a 10% power contribution is globally realistic for PV floated on various surfaces.
Physics World 4th Dec 2019 read more »