Crosstech Engineering has pioneered the use of water turbines to drive irrigation pumps directly. Individually designed turbines utilise the fall of the Canterbury Plains combined with the flow of a large irrigation race.
Typically, water is diverted out of a scheme irrigation race into an elevated intake canal and falls 3.5 – 7.2 meters through a crossflow turbine driving an irrigation pump via a speed up drive. A tailrace below the turbine returns the water to the main irrigation race. The smallest installation has a turbine mechanical power output of 30 kW, the largest 240 kW. Output depends on the resource available and the spray irrigation system demands.
These turbines eliminate pumping costs with minimal ongoing maintenance.
A typical capital cost of $150,000 for $35,000 annual saving (120 L/sec output) provides a 3 -5 year return on investment. Consequently, there are no concerns about electricity price increases into the future.
Environmental benefits include a reduction in electricity and/or diesel consumption, the harnessing of a local renewable energy resource with minimal environmental impact, multi purpose use of water rather than sole irrigation use, reduction in green house gas emissions and carbon credit production.
Ten installations have been completed since 2002 with one also generating electricity back in to the national grid. Further installations under way.