Here’s another idea for disconnecting from the mains electricity grid – not cheap to buy, but cheap to run on a pint of diesel per hour. It’s the WhisperGen off-grid heat and DC power generator sold by Volpower NZ Ltd, Auckland, distributor of Volvo Penta marine and industrial engines. The company shot to notice last year when, after a five-year product trial, it won a $300 million contract to supply British electricity and gas giant Powergen with 80,000 domestic AC units over the next four years. These will be installed in British homes as replacements for conventional hot-water boilers, running on natural gas to generate AC power and hot water. But natural gas is running out and rising in price.
Powering the camping fridge-size generator in the WhisperGen is a small Stirling engine, the original invented in 1816 by Rev Robert Stirling (search the internet for how it works) and only now commercialised on a mass scale by these clever folk in NZ. Off-grid users are a key market for Whisper Tech; so are commercial and recreational vehicles, the oil and gas industry and pleasure boats. Models available are a commonly sold 12V diesel fired unit, 24V diesel fired and a 24V kerosene-fired unit available on request. The diesel should be automotive grade and consumption is 0.75L/hour at maximum output. Electricity output 19kWh of power per 24 hours; heat output 5.5kW (19,000Btu/hour) via sealed liquid circulation. Noise level is 55dBA at 1m – “very quiet”, says Volpower. In operation, the WhisperGen charges a battery bank whose output is stepped up via an inverter for powering 230V household appliances. You also get space heating (convection) and hot water, which means scope for under-floor heating. And it’s environment-friendly because of the burner design and continuous combustion, and 90% conversion of the fuel’s energy to electricity or heat. Factory warranty is 2000 running hours or 24 months from purchase date. Price in New Zealand dollars is $20,700+sales tax, including the installation kit for a basic unit. Installation takes three days; labour cost is extra. www.whispergen.com Tel. 09 274 4305
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