Page - 160 - in Clean Water Using Solar and Wind - Outside the Power Grid

160 Clean Water Using Solar and Wind: Outside the Power Grid land use, although the area between the towers can often still be utilised for agriculture or forest. Offshore wind will of course have an environmental impact as well, but the area seldom competes with other uses. Solar PV does not necessarily need to occupy fertile land. Small-scale PV and solar heating installations have minimal land impact, as they are actively integrated into buildings and structures they serve. The power and energy outputs from a given area are summarised in Table 13.1. It is obvious that solar PV is very competitive in regard to land use, even if the capacity factor is relatively low for the actual area. In the US the National Renewable Energy Laboratory (NREL) (www. solarindustrymag.com/online/issues/) has studied the land footprint of utility-scale solar generation. There is a wide range of total land use. The average total land use was estimated at 8.9 acres (around 36,000 m2) per MW, or around 28 MW/km2 (compare with Table 13.1). Table 13.1 Energy output from a given area for different renewable sources (Olsson, 2015). Hydropower Wind Solar PV Power density MW/km2 0.1–17 5–8 20–110 Capacity factor 0.6 0.3 0.2 Annual energy output GWh/km2 0.5–90 13–21 35–190 The wind power land use requirement depends on both the size of the turbines and the extent of the terrain. In a hilly area the wind turbines may be located along the ridgelines. Wind towers on flat terrain are often positioned more uniformly and may require a larger land area. The footprints for wind farms in the United States average around 333,000 m2 per MW or a power density of 3 MW/km2 (NREL, 2012b). The space between the wind turbines on a farm can be large. However, only a small fraction (3–5%) of the land required is disturbed by the wind energy structures. The rest of the land could be utilised for agriculture and transport links. Naturally, in remote areas there will seldom be large wind farms; instead there will be stand-alone wind turbines, with quite a small land footprint. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user