Jane Powerson rechargeable batteries.
Much of our lives is powered by little cylindrical batteries: alarm clocks, radios, caller-display units on telephones and, of course, all those toys that whirr, ping, hoot and clack. Single-use batteries (or primary batteries, as they are known in the business) are an enormously inefficient way of delivering energy. They require 50 times more power to manufacture than they yield.
Once they've served their purpose, they must be disposed of. And while we can certainly earn green brownie points by recycling them, the route is a long and arduous one. All our household batteries are sent to Germany, where zinc (the main metal) is reclaimed and regurgitated into ingots, which are then used to make more batteries.
Rechargeable batteries are about four times the price of primary ones, but in the long run they're easier on the pocket (even when you add in the price of a charger) and are much kinder to the environment.
Most are now based on nickel metal hydride (NiMH). Nickel cadmium (NiCd) kinds are cheaper, but they store
less energy, contain more toxic chemicals and are more prone to "memory effect" (where a battery loses its capacity if it is habitually not fully spent before recharging).
When buying rechargeable batteries, go for the largest milli-ampere hour rating, denoted as "mAh". (An ampere is the amount of current produced when one volt bashes through the resistance put up by one ohm. Divide this by one thousand and you get a milli-ampere.)
The 1,300 mAh batteries may be a third of the price of 2,700 mAh batteries, but they deliver a third of the hours in energy, and need to be recharged more frequently, so their life span is much shorter than that of a battery with a heftier mAh. Most NiMH batteries are labelled as being good for "up to 1,000" charging cycles - but they will achieve that magic number only in laboratory conditions. Nonetheless, a battery that allows itself to be charged several hundred times is preferable to one that poops out after a single performance.
NiMH batteries usually take two or three charges to work up to their optimum efficiency, so don't be downhearted if they get tired after their first couple of outings. And remember, do unplug the charger when you're not using it.