Westminster City Council is doing its bit to save the planet by installing energy-saving street lamps in every thoroughfare in the borough, the BBC reports. The bold initiative follows a "successful trial" of the £1,000-a-pop Furyo Lanterns on Harrow Road which saved "on an average day", enough juice to light a house for two …
The numbers don't add up
I saw this on the BBC yesterday and couldn't believe how poor the maths was. Assuming the report is correct how can these idiots be allowed to keep their jobs?
Not the true ROI...
Although you should also consider what the cost of a regular street lamp is and their natural lifespan to get an idea of whether it is truly a 1450 year ROI. If the current lamps are going to be replaced as they fail, then it may be worthwhile.
BBC Science coverage just gets better...
Something's been lost in translation here...
The BBC also says "They were trialled in Harrow Road and saved, on an average day, enough energy to light a house for two days." Going on that, the saving per light would be around 1,500kWh a year.
(4,000kWh * 19% * 2)
That's a saving of between £60 and £150 per year (depending on what the council pays for electricity)
So the full 29,000 lights would save £1.74m-£4.35m a year, representing a payback of between 7 and 17 years, and reduce power consumption by around 5MW.
Good work, I say...
I wonder what the carbon footprint of manufacturing these fancy bulbs is?
Also, assuming that the existing lamps are sodium-based, they should be around 22-27% efficient. By contrast, flourescent lamps appear to be around 14% efficient.
So, fancy reflectors aside, what are the benefits of changing, considering what could be done woth £29m woth of investment in planting trees or, dare I say it, solar panels?
Another bit of eco-bullshit bandwagon-jumping from ignorant politicians, I fear...
Typical carbon footprint chasing
As usual, our government in its blind way chases the direct carbon footprint of a particular scenario, rather than investing money wisely.
So, great - the £20,000 aside, the street lamps might save ~17.6 tonnes of CO2 a year each (a respectable 510,400 tonnes per year for all 29,000 of the blighters, if they go ahead), but surely the £29m could have been better invested in cleaner energy, or even renewable sources themselves.
For example, off the coast of Cornwall they're trying to get funding for a 'Wave Hub' to kick-start a wave-power industry in the UK. (http://www.southwestrda.org.uk/news/release.asp?ReleaseID=1450). This starter system alone could put out up to 20MW, and according to the Carbon Trust, 'wave and tidal stream resources could provide up to 20 per cent of the UK's current electricity needs, given the right level of investment now from the public and private sector.'
" . . . how can these idiots be allowed to keep their jobs?"
They work for the council!
The maths may be wrong
Even after the quoted figures have been corrected as others have pointed out, the real question is whether the figures (in terms of what it costs to run or install the lights) actually reflect the true cost of running them, which cost should include the environmental cost. They probably don't, since the environmental cost is not completely known and is controversial where it is known.
That being the case it may well be rational for the council to try and do the real costing, allowing for (what they believe to be) the environmental and other costs, and decide to do something which looks, superficially, financially stupid.
On the other hand, they're a council. Stupidity is what councils excel at, so who knows.
And on the third hand: why don't they just not have so many lights on? If we could all get over being frightened of the dark, then may be we could live in a world which doesn't look like a giant piss-stain at night, where we could see the stars, and where we generally weren't quite so busy crapping all over the planet. Wouldn't that be a better solution?
If each light saves 1500Kwh that means that for 365 days a year, 12 hours a night the saving is 300watts while illuminated. Given that the average power used for a light is 48-65 watts (http://www.hillingdon.gov.uk/environment/street_lighting/index.php) I find this saving unlikely
it's worth pointing out that street lamps inthe UK haven't used timers since the early 80's - all UK street lamps use light sensors (that don't need to involve a single microchip!) - either they have managed to hang on to this 30 year old technology in Westminster or the beeb are just making stuff up again.
i can remember people going round adjusting each timeswitch in each lamp twice a year - something you don't see now - something which would take a crazy number of man-hours.
worth also pointing out that with those timeswitches the lights also used to go off after midnight... saving a hell of a lot of power!
(4,000kWh * 19% * 2) ?
I'm sorry, but you can't just pluck figures out of the air if you are criticising someone else's calculations. What are your sources for these dodgy figures?
Compare with this...
* An average house could be expected to light maybe an average of 4 rooms all evening (and morning through the winter)
* Say an average of 60W per room (some will be higher, some will be less, some will even use low-energy bulbs!)
* Assuming an average of 3 hours lighting required in the evenings and 1 in the morning throughout the year, so 4 hours per day.
So, using some "plucked from the air, but specified" figures:
Each house required ~ (4 * 60 * 4 * 365)Wh per year for lighting = 350.4KWh.
To reach your lower figure of £60 saving per year the council would have to be paying nearly as much as we are per unit! £60/(2 * 350.4) = 8.56p
@GettinSadda - you appear to be comparing one bulb with four bulbs. If your calculations involved comparing one street lamp with lighting every room in Windsor Castle then there's an even greater saving.
£1000 a pop? Gimmie a break! Sounds like the BOFH is doing the negotiation for the manufacturer. How about someone at the council grows a set of balls. Cut a deal where we say, ok, say we turn this into a national scheme rather than a limited local one. Say you sell us the bulbs at £50 a pop, multiply that by the number of street lights in the UK, and add to that the contract value of replacements, maintenance etc, the repeat business generated by other governments seeing the resulting savings and jumping on the band-wagon...
Or, alternatively, you continue to sell your £1000 a time bulbs on the open market and we give our massive contract to someone else, and good luck with that, by the way.
Yeah it's naive and over-simplistic, but it really shouldn't be.
Re: The maths .......
Well done Tim
I go with the no street light solution.
Go to rural France - No street lights - See the stars - No 'YUFFS' hanging about on the streets, wonder what the additional savings would be in reduced policing, property insurance and NHS costs?
Missing the point...
Except in the deepest darkest days of winter street lighting acts as useful night base loading for our now mainly slow transient coal and nuclear generation, the amount of which is only going to increase as the fast transient gas generation becomes more and more expensive to run. If the bulbs are more efficent at turning power to light then fine but it's a really crap way of trying to save any significant amount of energy
If people really want to save power its very simple - turn off the aircon that for some unknown reason is now appearing nigh on everywhere - its England ffs not Spain, do we actually really need it outside of plant rooms and hospitals?
Just to clarify
*The average house uses ~4000kWh of electricity a year, see: http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/hec.htm
*The 19% is approximate for the proportion of lighting as a total of household electricity use. Take a look at: http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/hec.htm
for a breakdown of the different types of consumption (on that page it accounts for ~23% of consumption as of 2005)
*Then x2 because the lamp saves enough electricity per day for two days of household use.
*The assumptions for electricity cost are based on the council paying between 4p and 10p a kWh. So, somewhere between the wholesale electricity price and current retail tariff.
Life Cycle Cost Needed
To make a fair judgment one needs to work out the life cycle cost of the two options:
1) x cheap bulbs + service costs + electricity + cost of co2 emission
2) y expensive bulbs + service costs + electricity + cost of co2 emission
The expensive bulbs cost more than the cheap ones but (afaik) last longer - therefore option two uses fewer bulbs, fewer worker hours replacing bulbs, less electricity and the externality in terms of CO2 is also lower.
So overall the calculations are a lot more complex and you cannot just rubbish the idea (or support it) without doing the above calculations...
As one other reader pointed out manufacturing costs must also be included. Disposal costs should also be considered (the older bulbs loose if there are more of them).
How many? how much?
The BBC report gives the total number of street lights as 15000, not 29000.
A saving of only £1.33 per light/year can't be right. I'm sure my energy saving bulbs at home are doing much better than that and aren't on for nearly as long.
One point missed:
The light emitted by low energy lamps drops over a period of time - in one recent article I read this was by as much as 50% in a single year.
Councils are obliged to maintain a certain level of illumination where lamps are installed (I forget the figures) - if these lamps dim over time, the councils will be spending more to replace them on a regular basis - and to fend off injury claims for trips / falls in dimly lit areas...
Standard low energy lamps also have a problem starting up in cold environments - and as we live in the UK...
Amazing electricity tariff?
I've had a thought: perhaps Westminster City Council pay so incredibly little for their electricity that the energy saved by each new street lamp over the course of a year only amounts to £1.33 worth of electricity at their prices.
Or maybe it's just that the person who came up with th £20k figure has got it very wrong.
A couple of points...
Sodium lights already use a tiny ammount of power - the exact reason that they are used! You often need to look at the design of the housing of the light as this is usually staggeringly inefficient (hence our orange skies at night)
Also - Light bubls cost a lot. Really, they really cost a lot, I used to work in lighting and some of our more sophisticated bulbs could top the one grand mark easily. You shouldn't think that commercially used bulbs are anything like your 60w bayonet fitting, or energy saving equivilant.
Re: BBC Science coverage just gets better...
>> (4,000kWh * 19% * 2)
You seem to be assuming a single bulb is enough to light the whole of Harrow Road. The article isn't clear if the combined saving of all the bulbs replaced on Harrow Road was enough to light two houses, or each bulb replaced saved enough to light two houses. It reads to me as though it is the former - however, as it doesn't tell you how many bulbs were replaced, this is next to useless. The more telling figure is that each the BBC reckon 15,000 bulbs will save £20,000 p.a. in total - £1.33 p.a. or 0.365p per day i.e. between 146 Wh and 36.5 Wh per day using for figures of 4-10p per unit.
Regardless of the maths, what I don't get about the article is why the author expects energy saving lights to pay for themselves. Regular street lights are an expense, not an investment, why should energy saving lights be any different. The article doesn't detail Westminster Council's plans for rolling out the the new lights, I see no reason to suspect that they will do anything other than replace old lights with energy saving lights as and when they need replacing (there is nothing in the article to indicate otherwise). Most importantly, the article fails to mention how the installation cost of the low energy lights compares to 'normal light' installation.
Heres a thought........
Now lets pretend for one minute it is the mid 1970's after a couple of very harsh winters when the media and 'scientists' were threatening global cooling. Money was wasted (about £2bn) trying to encourage us to look after the planet more etc etc.
Welcome back to the 21st century where the government 'scientists' are on the global warming bullshit road. This time however the billions they waste on trying to stop 'global warming' is going to come out of our pockets, yes you and me with green taxes, 'congestion' charges (make rail more effiecent and cheaper and this would not be a problem), putting the wrong rubbish in the wrong bin tax.....need I go on.
Wake up people we are running out of oil and coal and they are pinning the costs of new technology onto us. However the positive side of going greener is saving money, my bills have dropped. I have not done this to 'save the planet' but save my pocket.
I firmly agree (after 100s hours plodding through the web and looking at BOTH sides) that we produce far less CO2 than the media and government 'scientists' claim and that we are merely going through a cycle. Before you think I am talking a load of bollocks spend 5 hours looking through weather patterns over the last century. Compare that with sun activity and you will find that this 'warming period' is nothing to worry about. Lets face it we have just had the coldest and wettest last weekend in May for years.
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