Coanda screens in the Himalayas

For more than 20 years, we have exported our Aquashear Coanda Screens to many corners of the planet, Nepal being one of them. Nestled amongst the mountainous areas of this country, our screens help powering vital infrastructure in some of the country’s remotest neighbourhoods, many of which are completely off-grid. To date, Dulas has exported over 70 screens to Nepal, through the Kadoorie Agricultural Aid Association, (KAAA).

Namche Bazar, Namche, Nepal

KAAA has been using Dulas’s Aquashear Coanda screens since 2010. There are over 70 screen units located around Nepal, mostly in smaller run-of-river projects in remote areas where there is little or no grid supply. Whilst these remote regions may not have grid supply or easy access to fossil fuels, they do have water falling from the mountain rivers and glaciers of the Himalayas, which has enormous potential to generate hydroelectricity.


Aquashear Coanda screen units installed in remote regions of Nepal.

KAAA is a charitable organisation that provides remote, off-grid villages in Nepal with hydroelectric systems as part of its work to support communities. These systems include our Aquashear Coanda screens, which are used to optimise system performance.

Use the interactive map below to explore some of these schemes for yourself.

Nepal locations where some of Dulas’s Coanda screens have been installed

Interactive map: click on a pin to find out more

Separating potential energy from potential threat

Nepal experiences intense rainfall, which can result in a very strong flow of river water, often carrying significant quantities of silt and larger debris. Silt is filtered out of the water by the Coanda screens thus protecting the hydro turbine from excessive wear, however large debris carried in the water can physically damage the Coanda screens. The KAAA team have engineered out these risks by channelling off water from the main river flow into a settling pool ahead of the Coanda screens. This allows large debris to remain in the water course and a significant proportion of silt to settle out in the pool before reaching the screens.

What does an Aquashear Coanda screen do?

Interactive graphic: click on the circles to find out more

Coanda screens are used to filter the flow of water within run-of-river hydroelectricity schemes by excluding debris from the hydro system. The benefits are twofold – the hydroelectric turbine is protected from excessive wear, and fish and other river fauna in the water course are kept well away from the hydro system. The screens are installed on the downstream side of a weir, where water flows over the curved acceleration plate and down onto the screen material. The Coanda name is derived from the physical effect which the screens take advantage of – the Coanda effect – where liquid adheres to the screen surface, pulling the water into the sump which feeds the hydroelectricity scheme. Specially designed apertures in the screen material allows water to pass through the screen and excludes the unwanted silt and debris from the system.

Shared aims

As an organisation, KAAA aims to empower poor communities, helping them to help themselves. In addition to installing hydroelectric schemes, they undertake projects such as cliff trackways, horticultural training, and solar lighting – all of which can make a big difference to communities. At Dulas, we share this desire to improve people’s lives, and it’s always great to hear that equipment that we have shipped out to a faraway place is having a very real and positive effect on the lives of people within these remote communities.

Pictured on the photo, from left: Dylan Roberts, Matt Palmer, Dr Narayan Gurung and Chris White.

Paying a visit to Dulas HQ

Dr. Narayan Gurung (pictured) is Technical Director at KAAA. He explained to us that several developers in Nepal had seen Dulas’s Aquashear Coanda screens in action and were very impressed by their filtering ability, as they had seen lower performing screens employed elsewhere, which had been far less effective. By contrast, the Dulas Aquashear Coanda screens have been described as ‘magical’.

We were delighted to show Dr Narayan Gurung around our hydro department in Machynlleth and he was also intrigued by our solar powered vaccine refrigerators, which are used within immunisation programmes in off-grid areas around the world. He could see how these could be used to provide obvious health benefits for remote communities in Nepal.

Dylan Roberts
Head of Operations & Maintenance

For further information, feel free to get in touch.

Renewables Tel: 01654 705 000

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