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High Power

A farmhouse in Bhutan. Credit: Christopher J. Fynn (CC BY-SA 3.0)

A farmhouse in Bhutan. Credit: Christopher J. Fynn (CC BY-SA 3.0)

By Stephen Hughes

Micro-hydro power units could soon provide “SWAP’n’GO” batteries to villagers in remote regions in the Himalayas.

Bhutan is a tiny Himalayan kingdom nestling between India in the south and the Tibetan plateau in the north. Over the past few years I have led a team of scientists and engineers from Queensland University of Technology and the Royal University of Bhutan exploring the use of siphons to drain water from glacial lakes to reduce the risk of catastrophic flooding in the region (AS, October 2015, pp.34–36).

We are now also exploring the use of siphons to deliver hydroelectric power to remote villages. The advantage of combining a hydro unit with a siphon is that no extra plumbing is required to hook the generator to a reservoir.

We normally think of large-scale hydro plants such as the Snowy Mountains Scheme in NSW, but hydro can be implemented on a much smaller scale. Most sources of renewable energy can be implemented on such a “micro” scale, which is not true of fossil fuel power generation. We are unlikely to see a home coal-fired power station for sale in Bunnings, or a home nuclear power plant in Harvey Norman.

Hydro involves the conversion of energy from falling water into electrical energy. The amount of power delivered by any electrical circuit is equal to the product of voltage and current. Likewise, the amount of power produced by a hydro unit is the product of pressure and flow.

Hydro units can be set up in various configurations. If the water drop is only a few metres, a low-head system can be implemented with low pressure and high flow. If the water drop is tens of metres, a high-head system can be implemented with high-pressure and low-flow.

In Bhutan we experimented with high-head turbines. These turbines are smaller and lighter, and therefore easier to transport. Another advantage of high-head, low-flow is that a much smaller amount of water is required per unit time, and it’s possible to run multiple hydro units in parallel.

Despite the large-scale hydro projects that exist or are being built in Buhtan, about 5% of the population in the alpine regions close to the Tibetan border do not have access to electricity. Building transmission lines from the relatively low-lying hydro power stations to alpine regions would be prohibitively expensive. In the high-altitude regions of Bhutan there is so much water that a micro-hydro approach makes absolute sense as a cost-effective way of generating power.

We took five 10W/12V (DC) units to Bhutan sourced from a company in Hong Kong that cost AUD$8. While 5V and 80V units are also available, we chose 12V because 12V LED lights are readily available. A power rating of 10W doesn’t seem like much, but it’s enough for an LED light to illuminate a room in a house, and 12V to 5V (DC) car adaptors are readily available.

For our main experiment we inserted a 32 mm diameter polytube in a water tank supplied by a mountain stream at the top of the gardens, and ran it down to a square building called a chorten, which contained a prayer wheel.

Two micro-hydro units were connected to the pipe using a T-connector fashioned by the staff in the botanic gardens using a machete, metal disk and campfire (Fig. 1). The machete was used to cut sections of plastic pipe, and the campfire heated the disc enough to weld the two ends of cut tube together. We used a laser rangefinder to survey the terrain between the tank and hydro units.

The total vertical drop was about 20 metres. Although this comes under the category of a high-head siphon, we would have preferred a greater drop but this was the best we could do under the circumstances. In the alpine regions it would be easily possible to construct hydro power siphons with drops of 100 metres or greater. Water under pressure causes a small turbine in the unit to rotate, generating electrical power in a similar fashion to a larger turbine.

Staff from the botanic gardens attached two 12V LED lights to the chorten. We placed the micro-hydro units just inside the rear of the chorten so they were hidden from public view. The lights projected light onto the front of the chorten (Fig. 2).

This is probably the first time that micro-hydro units have been deployed in Bhutan. The hydro units seem fairly robust, since we received a report 6 months after deployment that they are still working.

In another location, north of the city of Paro, we trialled another micro-hydro siphon unit. The inlet of this siphon was inserted in a pool in a mountain stream, with the outlet on the edge of a river bank so the discharge water ran into the river. We demonstrated that the generator was able to power a 12V LED light and also charge a USB power bank. We connected the output of the generator to a car USB charger to convert the 12V output of the generator to the 5V required by USB devices.

The combination of micro-hydro units with USB batteries could be extremely useful in the alpine regions of Bhutan. A good analogy is how barbecue gas is distributed in Australia. Imagine the cost of providing this to every household in a city such as Brisbane, and compare this to the SWAP’n’GO system of exchanging gas cylinders.

Similarly, the cost of providing power lines to the most remote regions in Bhutan would be astronomical. However, the SWAP’n’GO model could be used to provide cheap electrical power to remote mountain villages.

The plan is to set up micro-hydro units in high altitude mountain streams, and charge a bank of portable batteries at the site. People would swap their depleted batteries with fully charged batteries. The electrical power generated by micro-hydro units would certainly be enough to supply the lighting for a village using LED lights. In these alpine regions, water is not a problem. Mountain streams are everywhere.

The next step of the project is to raise more money to go back to Bhutan to deploy more powerful micro-hydro units and rechargeable batteries in the high altitude regions to provide power to people living in these areas.

Stephen Hughes is a Visiting Fellow at Queensland University of Technology. To donate to the project visit