Light work

GREEN LIGHT
Bright ideas from Magazine readers

There must be a national effort to bring about a "green revolution", says the government. But what simple things can we all do to save the Earth?

GREEN LIGHT Green Light is a series of bright ideas from Magazine readers to help save the world

Everyone could help save the planet by making just a few changes in our household energy use. So the Magazine's inviting you to tell us how you think we could all be greener and more energy efficient at home, and that includes saving water - and we'll publish one a day.

Smart street lights

We're combining two of your ideas today. First this suggestion from Phil Laws, Durham:

"Fit sensors on street lighting so that they are only on when needed and have them set so that the light ahead of the direction of travel comes on to light your path."
Phil Laws, Durham

Why not make all streetlights which are out of town run on wind and solar energy. These lights are on all night, every night with very few people 'using' them. Simply a small 0.5m wind turbine and a small solar panel on top of the pole, and the light becomes 'self-sufficient'.
John Phee, Glasgow

Expert verdict

Malcolm Muir, editor of Highway Electrical News, is encouragingly positive about this suggestion.

"It's an outlandish idea but it sounds eminently sensible to me. Energy efficiency is a very topical issue for local authorities. With energy prices going up, local authorities, who are responsible for most street lighting are looking for way to cut their bills.

"The movement now is towards LED - away from the old sodium street lights, and they're already being used in streets and on housing estates." LED lighting would be more efficient than existing street lamps, he says.

"Coupled with this is the fact that a lot of councils are going over towards white light rather than orange. You get a much better light which all helps to tackle vandalism and street crime."

He's optimistic too that sensors on lights could work - a lot already have photo-electric cells which detect when the light has fallen below a certain level and when to switch on again.

There would however be something of a downside in losing street lights - research has shown that lights on main roads can cut accidents by up to 30%. Lack of lights could also make people much more fearful to walk in an area, even if they did turn on when people were near them.

In addition, if lights turned on when people were near them, they might actually think that they were more vulnerable to attack.

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How Green Light works

Send us your ideas - whether they are technology innovations, new or improved gadgets or simply tips on energy-saving behaviour - to the Magazine using the form below. If possible include drawings explaining how your gadget or idea might work. Send these to [e-mail], please making sure that the subject line is GREEN LIGHT.

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Your comments

Re: proximity sensors on street lights. Surely the electricity saved by turning the light off when there's nobody around is offset by the electricity required to actually operate the sensor? Kinda defeats the object, really...
Il buono gigante, Cardiff

Having street lights powered by wind turbines & solar panels is a great idea - provided of course that you're happy to have the streets in total darkness during any night when it might be very still.... 'cos there'll be nothing to power them then!
Adrian, Manchester, UK

If wind could be used to power street lighting, then the streets in my area would be extremely bright when it's blowing a gale!
LH, Tyne & Wear, UK

I have seen several speed signs that are solar/wind operated near stratford upon avon. perhaps this could be put in use all over the country and would save a lot of wasted energy
norma doyle, rugby, warwickshire, UK

I find it quite unnecessary to have motorways lit. To do so would lead to significant reductions in energy and financial costs. Motorways were never originally lit, so whose idea was it to do so? Have lighted motorways reduced accidents or just made driving easier for the motorist? If motorways were unlit drivers would take more care and fewer risks.
john breeze, Rainham, Kent

I had a similar idea a few years ago on this, not for urban areas but for motorway lighting. If you have ever stood on the side of a motorway you will know that the cars and lorries generate quite a bit of wind movement. If you have ever seen those advertising stands on garage forecourts that spin round in the wind. What you would do us fit these in about 2-3 meters up the pole, with a smal solar panel, put a baterry pack inside the pole, so that during the day the wind and solar energy can be stored as it trickle charges the battery, and so at night either the wind generator or battery powers the light. There are miles and miles of road lighting which could be replaced.
Graham Preedy, Basingstoke

Sirs, It's common schoolboy knowledge that wind can produce light albeit only momentarily.
ron leake, Christchurch, England

I suggest taking this idea further. Why not have road-side mini wind-turbines mounted on the central reservation of motorway? Fast moving traffic, especially vans and lorries, create a powerful wake that is felt as a wind. This wind could be used to power the road lights, and supply power to the grid during the day. It would even work on still days as there is always traffic. The turbines would be integrated with the central reservation barrier to avoid whirling blades and pedestrians mixing, and be designed to disconnect easily from the grid in the event of an impact during an accident.
Mike Wilson, London, UK

This is a great idea but using current technology would only be possible using LED derrived lamps for low power uses such as residential streets and sign lighting. Proximity sensors are of no real use on highway lighting as modern discharge lamps take 3 to 4 minutes to reach their optimum light output. The real hypocracy here is coucils moving away from low pressure sodium (yellow) street lamps to white metal halide units which are less than 50% as efficient - for example a 400 watt white lamp will emit the same light (approx) as a 160 watt yellow lamp.
Richard Groke, Beverley, East Yorkshire, UK

I think sensed street lighting would improve security, not reduce it, since burglars skulking about would trigger the lights and would know what part of the street they were in. I've often thought this would be a better form of industrial and shop security lighting. If you fit a security light outside your house you always use a people sensor. The only reason for business not to bother is cheapness of electricity. If there are streetlights on 24hrs/day in your area, you can get them fixed by emailing or calling your local authority. Just note the street names and send them a list. I did this some time ago and it worked. They don't care much because they don¿t pay per kWh, they just pay what the electricity company asks for, but if you contact them and ask them to get them fixed, then they will do it. If fitted with PV or a wind turbine, each streetlamp would need a rechargeable battery which, charged and discharged everyday, would only last a year.
Malcolm, Wirral, UK

The idea of movement sensors would not work with the vast majority of street lighting because the type of lamp used, commonly Low Pressure Sodium (SOX) which, being a High Intensity Discharge (HID) lamp requires an ignition and stablisation period of up to 20 minutes after switching on. You don't get full intensity straight away with HIDs, they have to warm-up. Also, it would probably be more efficient leaving it on, due to the large currents drawn from the electricity supply during striking (similar to florescent lighting.) Having thousands of HID's all over the UK randomly switching on and off when needed would also have dire consequences for the National Grid due to the quantity of spikes produced on the lines. This is why large rows of street lights turn on in sequence, not all at once! If LED lighting was employed however, this would enable the lamp to be switched on and off instantly, use less power and be much friendlier to the electricity supply. Trouble is 99% of st! reet lights are currently using discharge lamps.
Jim, Cornwall, England

Current sodium lights cannot be turned on and off at will, they have a cycle time. Once turned off, the vaporized sodium has to condense and settle to be re-ignited. If you turn it on before it does, it will light just partially depending on how much sodium it might still be around. LED lights have no such problem. Nevertheless, how are you going to turn on lights well in advance of people and vehicles, each moving at different speeds? A car needs lights turned well ahead of it if it is to see any obstacle partially out of its headlights, specially with other incoming vehicle with its headlights shining on your eyes. By the way, proximity sensors are usually motion detectors, which means that if you are standing still, waiting for the bus, the lights will turn off, as well as if you are under the bus stop shelter.
Daniel Barreiro, Barcelona, Spain

Nottingham University already has wind powered street light installed on campus! They seem to work well but I'm not sure if they are hooked up to the mains power for back up!
Jane, Nottingham, UK

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