Wind Power
Wind, in a similar fashion to sun, happens at specific times of day (late afternoon, nighttime). Coastal locations often have good wind resources due to the temperature differences between land and sea. Wind turbines can range from 500 W rooftop turbines to 16 MW (16,000,000 W) offshore turbines. Wind turbines are more effective at large scale and when sited offshore in “cleaner” wind. Clean wind is wind that is less disrupted by the local environment. However, small scale wind turbines can still be a viable alternative to solar panels for small scale installations when installed outside the tropics.
Wind turbines are more efficient at capturing energy than solar panels. Wind turbines can convert 50% of wind energy to power, while solar panels only have an efficiency of around 20%. The efficiency of wind turbines exceeds that of coal power plants which normally have an efficiency of 35-40%. Natural gas power plants have similar efficiencies to coal power plants except for combined cycle plants which can reach power efficiencies of 60%. Some offshore wind turbines are approaching 59% efficiency (also known as the Betz limit) which is the maximum energy that can be extracted from wind.
Wind turbines take up less land area than the comparable capacity of solar panels (unless there is available unused roof space for the solar panels). Wind turbines can make use of unused vertical space and free up land area. Offshore wind turbines also have the lowest carbon footprint of all energy sources (including the manufacture of the turbine) at around 11 g CO2 per kWh. Solar panels have a carbon footprint of 41 g CO2 per kWh. Natural gas has a carbon footprint of 450 g per kWh and coal has a carbon footprint of 900 g per kWh. Although onshore wind turbines have a higher carbon footprint than offshore turbines due to their lower energy production, they still have a carbon footprint between 10 and 70 g per kWh.
Wind Powered Water Treatment
Wind has been used for centuries to pump groundwater to the surface. Windpumps were developed in Persia as early as the 9th century AD. These windpumps elevated water from wells and irrigated fields with surface water. Older generation windpumps were only able to capture about 30% of the energy in the wind. Modern windmills have improved efficiency ratings around 40%. A modern windmill with a 2.5 m diameter rotor can lift water from 60 m underground in 30 km winds. Besides pumping, wind is also essential to the optimal operation of aeration basins and evaporation ponds.
Modern water treatment systems increasingly rely on electrical power. For example Reverse Osmosis desalination requires electrical power to power pumps. These pumps generate the required pressure to push water across semi-permeable membranes. Other water treatment technologies like electrodeionisation, electrocoagulation and UV irradiation also require consistent electrical power.
Wind power can be a more consistent source of renewable energy than solar power over long time periods, blowing even on cloudy days and at nighttime. However, solar power is more predictable, is easier to forecast than wind power and can be less variable over short time periods. Given the variability of wind, it can be difficult to develop direct wind powered water treatment systems as consistent power is often required. There are two options:
- Wind turbines coupled directly to water treatment systems producing variable supplies or water quality.
- Wind turbines coupled to battery systems (or pumped hydroelectric power) to ensure consistent supply and water quality.
Each location will have optimal conditions for different sources of renewable energy power generation. A range of variables needed to be considered to choose between solar, hydroelectric and wind powered water treatment systems. Moerk Water are experts in designing and constructing renewable energy powered water treatment systems based on location specific information.
Contact Moerk Water today to discuss the best renewable energy system for your location.
