Electricity from the elements

2011-08-24 00:00

WHEN Andy Wood and his wife Belinda were building their home at Sakabula in Merrivale, they balked at the cost of ­electricity supply. “The cost of an Eskom­ line rental alone was prohibitive, ­before even starting to consume any power. So we decided to go ‘off grid’ and I started to investigate alternative energy. I did the sums, and it was clear that an alternative system would pay for itself in about six years. What we have ended up with is a combination system that is still ‘a work in progress’. Some of its elements still need fine-tuning, but what we have is adequate for our needs.”

The Woods have a combination of wind, solar and gas, with a generator as a back-up. Their wind turbine is a useful landmark as it is visible from quite some distance away. The generator is now seldom used, and Andy has to “switch it on just to maintain it,” he explained. They use gas for cooking and space heating, while the combination of solar and wind energy powers everything else: water heating, lighting, and appliances that include a TV, dishwasher, washing machine and two computers (as both Woods work from home). However, they do not have a tumble drier.

“We get more value from the sun than from the wind, which is a backup for cloudy weather when there isn’t enough sun to generate what we need. There’s a big difference between the generating capacities of the two systems. We have 10 solar panels, one roof-mounted water ­panel and three sets of electricity-producing free-standing ones. A wind turbine is quite an effort to erect and maintain as it has working parts that require maintenance. On a mild, breezy day the turbine generates about two amps, but when there’s a Berg wind blowing, it can get up to 45 amps and the turbine sounds like a motorbike, it makes so much noise. We need winds of about 12 km/h to generate wind power. It would be better to have more solar panels, but for the moment we can get by on what we have.”

Energy generated by the turbine or solar panels is stored in a bank of 24 two-volt batteries, and then converted by an inverter from 48 volts to 220 volts, and fed into the home’s distribution board. Andy is a quantity surveyor who runs his own consultancy, which helped equip him to ­research and work on the home’s ­energy-gathering system himself. He explained that he had learnt by experience, and was still “tweaking” aspects of the arrangement. “There is an under-floor heating system formed by 860 metres of piping ­installed in the concrete floor. The idea is to pump hot water through the pipes just to take the edge off the cold in winter, but the system is not working yet. It still needs refining.”

Commenting on what it is like to live in a home powered by alternative energy, Belinda said it had required a change of attitudes and habits. “Some people find it amusing when I have to turn on the gas stove to boil a kettle of water, but you get used to it. It has taught the children to be more aware of environmental issues generally — when you are plugged into the coal-powered grid you just take it for granted. We have had to become a lot more energy-conscious, and run only one big appliance at a time. For example, we could not run the dishwasher and washing ­machine at the same time — there just isn’t enough power for that. We had a children’s birthday party here and I used an urn for several hours, which meant that by the evening there wasn’t enough power left to run the system, so we were in darkness until morning.”

Andy’s experience with designing and installing the system for his home has led him to become an alternative-energy adviser in addition to running his quantity surveying practice. Working with the company that supplied his wind turbine, he designs, supplies and installs alternative­energy systems for the domestic ­market.

His advice to anyone considering alternative energy is: “Go for it. It’s well worth it, particularly in the long term when you consider the rate and scale of increases in electricity costs. It does require a capital outlay to ­begin with, but the technology will pay for itself, and in time could also generate income. The cost of alternative technology is coming down all the time, while the efficiency of the technology is increasing. It has been estimated that by 2050 all homes will be built with alternative energy.

“What the government needs to do is investigate and build the kind of system that other countries have, in which electricity metres can run in reverse. People who generate power can sell it back to the state and feed it into the national grid. That would serve as an incentive to install alternative energy, and would help supply what industry needs,” Wood said.

• Contact Andy Wood at Space Projects at 082 365 5037.

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