Dunk-E drops in: micro hydro for the people

When it comes to renewable energy, we write mainly about different kinds of solar panels and wind turbines, a little about geothermal and biofuel, and hardly written anything about micro hydro – simply because there isn’t much we find to write about.

There’s a story right now about 500 so-called “micro hydropower plants” in Romania that ruined a river, but these are plants, and hardly micro.[1] The micro hydro we want is the equivalent of the small wind turbine: family-sized, inexpensive, easy to install and maintain, and with minimal impact on the environment.

An Irish company named Ár-nuaTec now offers exactly this solution. They call it Dunk-E, a micro hydro device that can produce a high output of electricity from small, low speed rivers or streams.

Dunk-E is a simple and descriptive name for the installation process of the turbine – “Dunk” the turbine in a river or stream and make your own “E”lectricity. (Anthony Glynn, Ár-nuaTec)

Other micro hydro solutions can require major construction, deeper or faster rivers, and larger drops in elevation. Above all, the installation can be a lot more complex than the average customer wants. The Dunk-E appears to solve all these problems in one fell swoop. The machine reportedly takes about two hours to install, and it requires no dam construction, canal digging or other messing up of the landscape. The Dunk-E is designed for shallow streams, and the minimum depth required is a mere 10 cm (4 inches) (!).

Here’s a video of the Dunk-E in action. With the cover removed from the device, you can clearly see how the water is funneled towards the blades to create a Venturi effect and increase velocity:[2]

Dunk-E specifications

• Output: 100–3500 W
• Dimensions: 1400/340/1000 mm (55/13/39 inches – width/height/length)
• Rotational speed: 18–220 rpm
• Weight: 180 kg (400 lbs)

River Requirements

• Min. River flow: 0.4 m/s (16 inches)
• Min. River head: 0 m
• Min. River width: 1500 mm (59 inches)
• Min. River Depth: 100 mm (4 inches)
• Max. River Depth without adjustable legs: 500 mm (20 inches)

The adjustable legs note suggests that deeper streams can also be used. It will be interesting to learn what the drive system is, as well as more details about the installation process – expect a follow-up in the future.

The Dunk-E is suitable for small households and small to medium-sized companies – i.e. customers with small to medium-sized electric bills. If your energy requirements are high, multiple units can be linked in a series to increase the amount of electricity generated. Perfect.

The Dunk-E aims to make micro hydro more economically accessible as well. A typical micro hydro solution takes at least 12 years before a return can be seen on the investment. The Dunk-E takes less than 10 years. The cost of a 2.3kW device including installation starts at €9,350 (excluding VAT). A five year warranty covers the unit.

Ár-nuaTec is a mixture between Irish and English. Ár nua means Our new in Irish, and Tec is short for Technology.

We love the name. Ár-nuaTec is a fairly new company, and they’re still getting started with distribution. They report they are “currently deploying 8 units throughout Ireland and the U.K over the next 6 months, and have started a soft launch recently in Ireland.” We’ve also read they won the Business Category award in the 2014 David Manley Awards, and have received a €250,000 order for the Asian market.[3]

On the How Fast Is My River? section of Ár-nuaTec’s website, you can find instructions on how to gauge the speed of your river or stream. “All you need,” they write, “is a river, an empty bottle, a stop watch, a measuring tape and 15 minutes of time.”

This easy-going attitude completely sums up the Dunk-E for us. Micro hydro is suddenly a lot friendlier than it used to be.

See the Ár-nuaTec website for more information: arnuatec.com