Read on for the answer for the above question and two other

Yes and no. Offsetting can work but it is based on a series
of untestable assumptions. One of these is that offsetting activities, such as
planting trees or installing energy-efficient light bulbs, wouldn’t have
happened otherwise. Paul Hooper, from the Centre for Air Transport and the
Environment at Manchester Metropolitan
says we can’t prove that these activities wouldn’t have happened anyway.
Another problem is the large amount of variability in the schemes. Different
carbon calculators give out wildly different emissions figures for the same
flight, and the cost of offsetting a tonne of CO2 ranges from about
£2 to about £18 depending on how it is done. ‘It’s a minefield’, says Hooper.
His advice is to use the carbon calculator provided by the International Civil
Aviation Organisation
and then offset your flight with an UN-certified scheme. Better still, he says;
don’t fly in the first place. Should we all be taking more holidays locally?


What’s worse, the CO2
put out by a gas-fuelled car or the environmental effects of hybrid-car

According to the UK-based Environmental Transport Association (ETA), the
most efficient conventionally powered cars are slightly less detrimental to the
environment than hybrid models. However, it points out that the current crop of
hybrids won’t evolve without customers willing to invest in what is still
frontier technology. If you’re not quite sure, a hybrid car is basically a fuel
efficient car that has two motors – an electric motor and a petrol powered
motor. It also has a special system to capture braking energy to store in an
onboard battery. Why a hybrid? Why not a straight gas or electric powered car?
After all, one of the basic rules of science is the more complex the system – two
motors instead of one – the more often it will break down. This is the main
reason many boat owners prefer one motor instead of the “double trouble” of two
– despite the obvious safety advantages. This is a hard question and, in the
minds of some experts, not fully answered.


If I switch the light
on and off every time I enter and leave a room, does this use less energy than
leaving it on all evening?

Switching the light on and off does save energy, but there
is a catch. Every time you flip the switch, the bulb takes a jolt of
electricity, which shortens its life. Studies by the Electric Power Research
Institute (EPRI) in Palo Alto, California, found that turning low-energy
compact fluorescent bulbs on and off at frequent intervals can shorten their
lifespan by as much as 75%, which brings us to the same old problem of using
more energy to produce new bulbs than we would save by switching them on and
off often. The EPRI’s director of energy utilisation, Tom Reddoch, suggests
it’s best to leave energy-saving bulbs on if you will be out of the room for
less than 15 minutes.

The CAB Abstracts database
has over 20 000 records on environmental impact.

Source: New Scientist No. 2682, vol 200, Nov

1 Comment

  1. Robin Smith on 7th October 2009 at 11:58 am

    With these configurations, hybrid cars show a fuel mileage of 60-70 mpg as compared to 20-40 in regular cars. Hybrid cars are fuel efficient in the city.

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