Frozen water heats homes

In the headlong pursuit of delivering cheaper energy that does the environment no harm, German company Lsocal has found that frozen water is doing the trick. Lots of frozen water in fact. It’s the latest breakthrough in a race for cheaper ways of providing household energy as unit prices threaten to rise to unaffordable levels.

What the vast majority of householders in the western world still do is switch on the boiler or its equivalent, loading expensive energy down from the central grid. Yet in a few years time, the days of using networked power may seem almost as primitive as cutting down trees for firewood as companies specialising in renewable energy devise innovative options that replace the first wave of renewable household power.

Lsocal’s solar ice tank works in a fusion of ice, earth, air, rain and the sun. During the summer, water that’s surplus to domestic needs is accumulated in a solar collector and piped into the ice tank. As the colder season approaches, the water is control-cooled to zero celsius and converted to ice. Since the tank is underground, the ice will hold its temperature for an extremely long time.

Here’s the surprising bit, at least for non-scientists. Crystallised water produces a lot of heat, quite enough energy to heat domestic water from zero to 80 celsius. Meanwhile, this energy sits in the ice tank, ready for action when the house’s solar power can no longer do the job as temperatures fall. At that point the ice tank mobilises itself under a fully-automated process and starts delivering energy. And when it gets warm again, the ice melts and cool water is now put to the job of preventing the house from getting too hot.

In Sweden, so-called ‘passive houses’ are becoming almost standard. Among various low-tech methods to reduce energy use, they have dark exteriors to attract the sun and some even harness the heat of their occupants.

Whatever systems are used, the German-developed PassivHaus technology would pull all systems together into an integrated platform that measures and manages them. All the components of the domestic energy infrastructure – heating, water, solar, batteries, thermostats and everything else – “talk” to each other on a screen. They discuss whether the owners are in or out, the state of the weather outside and how it relates to in-house needs, how to make sure there’s plenty of power at peak times and just enough at low-usage periods, even whether the car battery is charged up and ready to go. And PassivHaus can even be operated from a mobile phone.

Some technologies like the geothermal heat pump have been available for decades but are only now becoming more common as energy prices rise high enough to bring them in out of the cold. Increasingly common in America, the pump harnesses the steadier temperatures that are constant a few feet below the earth’s surface. Warmer in winter and colder in summer than outside temperatures, the space acts like a cave and the pumps essentially draw up the cave’s temperatures to keep houses warm or cool, as desired.

Although they may be several times more expensive than alternative technology, heat pumps typically pay for themselves in five to ten years.

ut sometimes we don’t need technology at all. As the US Environmental Protection Agency points out in its Green Building programme, 20 percent of ducted heat – mainly air-conditioning – simply vanishes through poorly sealed pipelines.