Thermal water pump could aid farmers in developing nations

A water pump that uses thermal energy from the sun is to undergo field testing before potentially being used by farmers in the developing world for irrigating fields.

The device uses a non-inertive-feedback thermofluidic engine (NIFTE) that converts relatively small temperature differences between its heat source and heat sink into mechanical force.

It does this without any electrical supply or mechanical moving parts, instead using liquid pistons that move up and down in response to pressure variations, caused by boiling and condensation. Because of this it can hopefully be produced relatively cheaply, with a cost of £50 per pump being muted.

After 10 years of research and development at the Universities of Cambridge, Exeter and Oxford, and now commercial outfit Thermofluidics, the pump will be tested at a site near Tiverton, Devon in the coming months.

Dr Tom Smith, co-founder of the company and inventor of the pump said: ‘Essentially we want to take a technology that has been tested in a controlled environment in the lab into a hostile environment and kick it around the wheels, so to speak. Before we incur the high tooling costs that we’ll need to in order to produce units as cheaply as we hope to be able to, we need to make sure that we haven’t got some kind of fundamental flaw in the design.

‘There are fragility issues around solar collectors however they’re designed and we don’t know if there’ll be any long-term loss of working fluid or reaction with the water we’re pumping.’

Nevertheless, Smith is hopeful and investors, including the Carbon Trust, have contributed a total of £400,000 towards the £500,000 needed for the latest round of trials.

Despite having potential for use in the developing world, Smith is keen to point out that the commercial outfit has a number of different uses in mind.

‘It wasn’t really designed with the developing world in mind but rather with technology in mind. There’s a common misconception that necessity is the mother of all invention, but actually if you look in depth you’ll find that often the technology leads the application – so some new physical principal is played around with in the lab  and then people go out looking for application for it. That’s pretty much the case with us.’

Thermofluidics has recently received a grant from the California Energy Commission for a slightly different invention that can pump water from deep below the ground or a significant height above it.