When you consider the water footprint of your lifestyle, remember too that all energy sources have an associated water footprint.
If there were ever to be such a thing as an ‘average’ South African household, it would consume 6,000 kWh of electricity per year, and in the process, ‘burn’ about 9,000 Ltrs of water. One car which averages 15,000km a year and consumes 8Ltrs/km of petrol or diesel, would therefore consume an additional average of 6,000 Ltrs of water annually through its fuel consumption alone.
South Africa is a comparatively water stressed country. Population growth, economic development, increased urbanisation and adverse effects of climate change will lead to increased stress – in some regions more than in others. Some of the key upland watersheds for the major river systems already show statistically significant drying trends as a result of changing climate.
The high water use in the energy sector puts a strain on the scarce water resources in the regions where coal mining and coal-fired power generation takes place, in addition to that water pollution caused by coal mining and the coal-ash deposits (as just one example) impact significantly on the quality of ground and river water.
Coal mining, coal-fired, hydro and concentrated solar power stations, coal-to-liquid (CTL)-technology, crude oil refineries, ethanol refineries and energy crop agriculture all have significant water footprints. Activities which involve coal and crude oil not only use up scarce water resources but also contaminate the downstream water bodies now and for many decades to come. Some interesting water facts:
- 1 kWh produced in South Africa by a coal-fired power station uses 1.54 Ltrs of fresh water – taking both water use in coal mining and energy generation into consideration.
- Dry cooling technology reduces the water consumption for electricity generation by up to 95%.
- Carbon Capture and Storage (CCS) will at a minimum, double industries such as Sasol and Eskom’s water use.
- 1 kWh produced by a hydroelectric power station consumes roughly 70 Ltrs of fresh water through evaporation off the reservoir surface area. Thus, any industry which requires the creation dams (which increase surface area and thus evaporation) must add evaporation to water consumption.
- 1 kWh produced in the Great Karoo by a Concentrated Solar Power Plant will use about 0.1 Ltrs of fresh water, when dry cooling technology is used.
- 1 kWh produced by a Solar PV or a Wind Power plant will use 0 (zero) Ltrs of fresh water.
- 1 Litre of petrol or diesel refined from crude oil uses 2.5 Litres of fresh water in the refining process.
- 1 Litre petrol or diesel produced by Sasol applying the Coal-To-Liquid-technology uses 7 Ltrs of fresh water (excluding water consumption for coal mining).
- 1 Litre of biofuel (ethanol) produced from maize or celluloses consumes between 2 and 10 Ltrs in the refinery only (not included is the significant water use for irrigation).
- Hydraulic fracturing (fracking) will use up to 20 million litres of fresh water in a single well. Hundreds of wells are proposed for The Great Karoo. Fracking pollutes ground water.
- Eskom’s water consumption is similar to the water use of the entire City of Cape Town! And so is Sasol’s.
Dry cooling technology and improved CTL-technology can significantly reduce water consumption for energy generation.
In addition to green house gas emission considerations, it is also important to consider the impacts of our lifestyle habits involving energy choices, on fresh water resources. Any effort spent on energy use reductions and a sharpened awareness in the choices we make will impact directly on our water footprint.