Graham Cashion’s enthusiasm for harnessing the power of water for electricity was the driving force behind construction of a micro-hydro system in Branxholm Tasmania. The 7.5 kW generator converts 120psi of water pressure into 120kWhr of energy each day, supplying all the electricity needs for Tin Dragon Trail Cottages, eco-tourism retreat. Here I describe the system and its construction over three years: 2010 to 2013.
Graham’s Dream of Building a Micro-hydro System
Graham worked for the Hydro Electric Commission for five years, before National Service call-up in 1972. In 1968 the 18 year old Graham was snapped emerging out of the inspection bay of turbine No 3 at the Tarraleah Power Station (Tasmania)—the same year he received the top apprentice-of-the-year award. Over decades he continued dreaming about putting his experience into practice by building a micro-hydro system. In 2010, after establishing an eco-tourism retreat in North East Tasmania, he made his dream a reality.
The Construction Team Effort
Graham boasts that it took himself, a seventy year-old and a young boy, “ to achieve what the local Council couldn’t achieve—pipe clean creek water to Branxholm.” Standing near the micro hyrdo tail race are Ron (L), James (our son) and Graham. Ron says, “We done a bloody good job, too!”.
The dig up the final hill to the weir in 2010. Over the 3km route from the property to the creek, Graham was careful to avoid felling any large trees.
The deeply-buried 150mm galvanised steel pipe, air-bleed and inspection point are no longer visible. A rock cairn covers them. Graham is standing on the concrete spillway below the V-notch weir he constructed in 2010.
Graham completed the generator shed in 2013. Water feeds via the pipeline into the generator then dumps onto a concreted tail-race into the farm dam and into the nearby Ringarooma River. Visitors can see the generator, exciter and inverter through a large glass panel on the side of the shed. Graham loves talking to visitors about the micro-hydro and will gladly take them for an inspection of the pipeline and weir.
Micro-hydro Need Ongoing Maintenance
After connecting to the grid in 2013 we were excited to flick the switch and celebrated receipt of Renewable-Energy Credits and first power bill showing a credit! However, a micro-hydro is not without costs and problems. Here, James is helping Graham clean out the generator jets after a heavy rain event sent stones down the pipeline.
Air bubbles can trap in the pipeline. Graham routinely checks the air-bleeds along the line. Notice that the valve is hidden. Graham suspects past damage to the pipeline and weir have been the work of local Branxholm vandals.
At the V-notch weir, nearly 100m above the generator, water flows into 3km of buried pipe. Graham routinely monitors the flow. When water stops flowing over the weir Graham shuts off the micro-hydro intake to maintain environmental flow in the creek.
On the day we were photographing for this blog, Graham surprised a man with his dog fossicking for gem stones near our weir. In the past some fossickers have damaged our weir. One person with a metal detector dug up part of the pipeline! While they were chatting the fossicker’s dog made herself at home in the driver’s seat of our 4WD.
Christine and Graham are planning an alternate energy workshop on their property in September 2019. Interested in learning more about this system design or micro hydro in general? You can contact Tin Dragon Trail Cottages for more information or register your interest here.