Environmentally-friendly power can be generated from many different renewable energy sources, not just concentrating solar power. Of these, wind, geothermal and biomass are the most developed, but rapid advances are also occurring in wave and tidal energy. All could be integrated into power and water supply solutions.

Given Australia's sunny climate, abundant land and need for water, concentrating solar power currently offers the best combination of cost effectiveness and small environmental footprint for combined power and water solutions. With a series of large concentrating solar power plants now under construction in California and Spain, prices are falling rapidly for the technology. Even so, renewable energy is becoming a highly-competitive, highly-innovative field As a result, there is scope for other environmentally-friendly power and water combinations solutions to be deveoped in the future.

Below is a look at some other renewable technologies that could be integrated into power and water projects.

Wind. This is an abundant, low-cost resource that exists in most parts of the world. What's more, wind farms are even being built offshore. Wind is, at present, the cheapest form of non-hydro renewable energy, a title it may eventually lose to geothermal. While it offers great promise for powering desalination, this may largely come through power purchases of renewable energy off the grid by desalination plant operators instead of generating wind energy onsite.

Hydroelectric. Hydro power is produced through the force of falling water. It accounts for a significant percentage of Australia's electricity generation capacity. It has advantage of being able to provide both base load and peaking capacity to the electricity network. However, large hydro resources are largely tapped out, and the potential for generating hydro power near seaside desalination plants is limited.

Biomass . This kind of energy is derived from burning plant and animal material, such as wood from forests, residues from agricultural and forestry processes, and industrial, human or animal wastes. It can be colocated next to desalination plants, but the difficulty lies in finding large biomass resources near coastal areas.

Biomass can be used directly for electricity generation, steam for industrial uses, heating, cooking or indirectly by converting it into a liquid or gaseous fuel (eg ethanol from sugar crops or biogas from animal waste). An example of biomass used for renewable energy generation in Australia is the use of sugar cane waste, or bagasse, for electricity production in sugar mills.

Waves. Wave energy results from energy transmitted from wind to the ocean surface. Ocean waves can travel long distances before reaching coastlines and releasing their energy. There are technologies under development to capture this energy for conversion into electricity. There are also small-scale trials in wave-powered desalination. This is a very promising technology for bundling with desalination.

Tide. Tidal energy results from harnessing the massive movements of the ocean. Now exploited on a small, experimental scale, it holds huge promise for nearly limitless, highly-reliable electricity. It also can be applied to desalination.