Much of New Zealand is powered by large scale hydroelectric power systems. The ‘Off The Grid’ solution is a smaller version of this called a micro-hydro. Based on the same principal as a hydroelectric dam they use gravity(fall) to pull water down a pipe until it has enough force to turn a turbine and generate power.
Micro-hydro is a proven technology with the Pelton and Turgo wheels being invented in 1870 and 1919 respectively. It works particularly well in conjunction with a solar array as it provides a constant amount of power 24 hours a day, 7 days a week, which helps to solve one of the drawbacks of a solar panel based system.
The micro-hydro system themselves require little maintenance beyond a bearing replacement every year. Time is more likely to be spent on the water supply with common problems being floods, air and debris blockages, or trees falling on the line. Each installation has it’s own challenges but as time goes on the problems are sorted out and the systems become more reliable.
The initial cost of the micro-hydro is quite low although the total cost of the system can be dependant on just where it is installed. Unless there is a large amount of fall you will need to factor in the purchase of a pipe to carry the water from upstream. A larger pipe will cause less friction generating more power. There are online calculators that give an idea of what is required for each situation.
Low Head Microhydro example
A low head microhydro with 20m of 400mm pipe with a 28mm fall and a 20l/sec flow might generate 125W.
The all-weather PowerSpout LH is one of the most reliable, cost-effective generators around.
400mm x 20m
High Head Microhydro example
A high head microhydro with 150m of 61mm pipe, a 30m fall, and a 20l/sec flow might generate 399W.
The small (18 inches wide), all-weather PowerSpout PLT is one of the most reliable, cost-effective generators.
61mm x 150m
Last updated on the 06-04-2020