The facts and fictions of how to be green

Published on Wednesday 12 November 2008 22:39

TRYING to be green raises so many questions it can be difficult to know where to start. Can those envelopes with windows be recycled or not? And should we bother recycling at all because most of it will end up being shipped to China, generating harmful emissions in the process?

These and other questions are addressed in New Scientist this week, and today The Scotsman attempts to offer some answers and dispel some myths.

Can exercise machines in gyms be used to generate electricity?

Yes. A gym in Oregon in the United States has already successfully used bikes to generate electricity. There is even a device, called a Pedal-A-Watt, that can be hooked up to a normal bike, allowing a cyclist at home to generate enough electricity to power a television. Or it can be stored in a battery to use later. An hour’s cycling could power a low-energy light bulb for eight hours.

Does cycling rather than getting a bus really help the environment? How about the carbon emissions created by the energy required to power my legs?

Cycling is much better for the environment, according to New Scientist. A 12km commute on a bus generates 164kg carbon per commuter per year. Somebody cycling that distance would burn about 50,000 calories a year – roughly the amount of energy in 22kg of brown bread.

A kilo of brown bread has a carbon footprint of about 1.1kg, so switching from public transport to a bike saves about 140kg of carbon emissions per year.

Doesn’t switching the light on and off when entering and leaving a room use more energy than just leaving it on?

No, switching the light on and off does save energy. However, it also shortens the life of the bulb, by as much 75 minutes for energy-saving varieties.

How clean do pizza boxes need to be to be recycled?

Pizza boxes are often not recyclable because grease contaminates the cardboard, making it useless to paper mills.

Is it worth recycling when lots of it gets shipped to China, which must have a high carbon footprint?

Yes. Shipping recyclables to China uses 10 per cent of the carbon saved by recycling.

Many container ships used for trade with Europe would head back to China empty if they did not carry waste.

If I offset my flights, can I fly as much as I want?

This is a tricky one. Although offsetting can work, schemes vary widely depending on the carbon calculator used. The cost of offsetting a tonne of carbon dioxide, according to New Scientist, ranges from 2 to 18.

What is the most fuel-efficient way to drive?

Smoothly. Experts suggest avoiding dramatic braking and acceleration and moving through the gears quickly, changing up before you hit 2,500 revs per minute. Driving at 55mph is up to 20 per cent more fuel-efficient than driving at 75mph. Underinflated tyres can increase fuel consumption by 6 per cent. Carrying an extra 25kg in the car decreases fuel efficiency by 1 per cent. And short trips should be avoided, because a cold engine uses twice as much fuel as a warm one.

Is a full commercial plane more fuel-efficient over long distances than a car?

Not if the car is also full. EasyJet calculates that each passenger accounts for 95.7 grams of carbon dioxide per kilometre, compared with 164g for someone travelling by car. However, according to New Scientist, a full car would produce just 41g of carbon dioxide per kilometre for each of its four passengers.

Can I save the planet by staying slim?

Apparently not. Although obese people may eat more and require more fuel to move them around in vehicles, potentially adding to climate change, slim people usually live longer. So they will emit tonnes of extra carbon dioxide as a result.

Can I put envelopes with windows in the paper recycling?

It depends on your local authority. For some paper mills they are too much of a contaminant, but others can cope with them. It partly depends on the grade of recovered paper being produced.

Check by using the postcode checker at recyclenow.com. Alternatively just remove the window before recycling.

Will washing my clothes at 30 degrees get them clean?

Research has suggested washing with biological detergent at 30C killed only 6 per cent of dust mites and left traces of allergens, such as pollen grains and dog skin cells.

However, a study by the Energy Saving Trust has shown that while only 2 per cent of UK households were washing at 30C in 2002, five years later that figure was up to 17 per cent.

How bad is barbecuing for the environment?

It has been calculated that in America on 4 July, when more than half of households have a barbecue, 225,000 tonnes of is released into the atmosphere.

This is equivalent to burning 2,300 acres of forest.

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