Need something for powering that remote, off-grid shed? A clever new renewable power system could be just the answer. Emily Padfield went to have a look
The idea of a source of electricity that requires no fuel, can be set up in little more than an hour and is easily transportable is an attractive one. But is it feasible?
Cornish company Kraft Maus believes so. It’s a simple concept, says designer Jonah Kinross. “The 1kVA unit consists of four separate components: The control module which contains the electronics and safety components, a storage module containing gel batteries, a wind turbine and photovoltaic (PV) panels.”
The company is aiming the technology primarily at aid agencies and the military, but sees a niche for outlying areas where connecting to the grid would be unfeasible.
Called the Fuel-Free Portable Power System, the system uses DC power supplied from the wind turbine and solar panels to charge gel electrolyte batteries.
Power is then chanelled through the control module, which shows information like how much power is being discharged, what the net charge is and how much energy is left in the batteries. To enable the unit to continue charging constantly, there are two external dump valves to provide overcharge protection, explains Mr Kinross. “We’ve tried to make the system as simple as possible,” he explains. “It’s impossible to plug the wrong cables into the wrong connections. When the batteries are full, the module regulates a trickle charge to provide a continuous top-up.
“We’ve had a great deal of interest from the military. The cost of a gallon of fuel to run a generator adds up to $150 when you take into account logistics and security, so having a system like this which can be up and running in little over an hour and that can produce 240V power without fuel is clearly beneficial.”
The unit itself has a charge of up to three hours to enable power to be used to set it up, meaning that at no point is the system without power.
Kraft Maus will carry out the design, specification and installation of a system. “We assess the site for a month to establish what set-up would be most suitable using a light meter and anemometer. Depending on the results, this could mean that several PV panels are needed if it’s a particularly light area or if it’s windy a larger turbine could prove more efficient.”
“The 1kVA unit produces both 240V AC and 24V DC power, and it’s substantial enough to power an air compressor,” says Mr Kinross.
“In an aid agency situation, we see it being able to constantly provide light and power refrigeration equipment for medicine and telecommunication systems. But for farming it’s enough to run power tools, pumps and air compressors.” At the demonstration, the set-up consisted of a 300W turbine and two 500W PV panels, and was easily capable of powering a 750W drill and two 60W lights. Both 600W and 1kW wind turbines can also be connected according to wind availability.
It’s thought that the Kraft Maus system is the first in Europe to provide a truly portable and integrated renewable power source. “Because it uses both solar and wind power; if there’s no wind the photovoltaic panels still provide enough power to charge batteries and vice versa.”
Although the first units to be produced supply 1kVA continuous power, the company plans to produce 3kVA units that can be joined to supply up to 12kVA continuous power. These can, in turn, be connected to a back-up generator to protect against a sudden draw of power.
To prevent any damage to the electrics, there’s a simple short-circuit protection system and there’s a turbine stop switch and relay switch to prevent misuse.
Leaving the system outside shouldn’t be a problem, either, as it’s IP67/68 rated for protection against the elements.
The system costs about £9500 and includes the wind turbine, solar panels, control panel and battery module. “If you compare the system to one that uses a generator, fuel savings should mean a return on investment of about 18 months.”