When we moved to our house a year ago, we felt that one easy way to improve the way we consume energy was to go cordless. We didn't have many power tools, so the idea was that whenever we bought one it would, if possible, be cordless. The idea was that by using stored energy, we could recharge during off-peak times. Here in Ontario, the power company has not started metering according to the time of use, but there have been murmurings that they would, and I believe they should. Reducing peak demand could be a significant component of the provincial government's current strategy to eliminate coal-fired power stations. Using cordless tools, we are also ready to recharge with electricity from solar panels, if we ever get enough cash to go that route.
The biggest cordless electric item we have bought is a lawnmower, and I am happy to report that it does the job reasonably well. It's quieter than gas mowers, and doesn't pollute the neighbourhood. It is not pollution-free, since the electricty we are using is not green, but my guess - and I could be wrong - is that even coal-fired power stations have lower emissions from generating the amount electricity we use to cut the grass than are produced by the millions of gas lawnmowers brought out every week. I am not in favour of coal-fired power, but at least cordless lawnmowers can reduce peak electricity demand and can make use of energy sources that are not derived from fossil fuels.
There was only one model to choose from in our area: the Yardworks 24 volt 19 inch mower. By my calculations, it does about 9,000 sq ft on one charge if I keep the grass cut regularly. Unfortunately we have around 10,000 sq ft of lawn, but our plan is to drastically reduce that, replacing some of it with productive areas (vegetables) and low-maintenance indigenous plants that don't require watering (another topic for another day).
Update on 4 June 2007: And now you can ride it!
Update on 28 Feb 2009: The Brio cordless electric is now available in South Africa.