Switching off your lights has a bigger impact than you might think, says new study

June 30, 2010
Switching off your lights has a bigger impact than you might think, says new study
Fossil fuel power stations respond to changes in electricity demand

(PhysOrg.com) -- Switching off lights, turning the television off at the mains and using cooler washing cycles could have a much bigger impact on reducing carbon dioxide emissions from power stations than previously thought, according to a new study published this month in the journal Energy Policy. The study shows that the figure used by government advisors to estimate the amount of carbon dioxide saved by reducing people's electricity consumption is up to 60 percent too low.

The that supply vary in their carbon dioxide emission rates, depending on the fuel they use: those that burn fossil fuels (coal, gas and oil) have higher emissions than those driven by nuclear power and wind. In general only the fossil fuel power stations are able to respond instantly to changes in .

Dr Adam Hawkes, the author of the new study from the Grantham Institute for Climate Change at Imperial College London, says the government should keep track of changing carbon emission rates from power stations to ensure that policy decisions for reducing emissions are based on robust scientific evidence. The new study suggests that excluding power stations with low carbon emission rates, such as wind and nuclear power stations, and focussing on those that deal with fluctuating demand would give a more accurate emission figure.

Scientists advising government on for the best ways to reduce electricity demand currently use an estimated figure for emission rates. The new study shows that, at 0.43 kilograms of carbon dioxide per kilowatt hour of electricity consumed, this figure is 60 percent lower than the actual rates observed between 2002 and 2009 (0.69 kilograms of carbon dioxide per kilowatt hour), meaning that policy studies are underestimating the impact of people reducing their electricity use.

Dr Adam Hawkes, author of the paper, and a Visiting Fellow at the Grantham Institute for Climate Change at Imperial College London, said: "One way governments are trying to mitigate the effects of climate change is to encourage people to reduce their energy consumption and change the types of technologies they use in their homes. However, the UK government currently informs its policy decisions based on an estimate that, according to my research, is lower than it should be.

"This means any reduction we make in our electricity use - for example, if everyone switched off lights that they weren't using, or turned off electric heating earlier in the year - could have a bigger impact on the amount of carbon dioxide emitted by power stations than previously thought. However, this also acts in reverse: a small increase in the amount of electricity we use could mean a larger increase in emissions than we previously thought, so we need to make sure we do everything we can to reduce our electricity use," added Dr Hawkes.

Dr Hawkes drew upon 60 million data points showing the amount of electricity produced in each half-hour period by each power station in Great Britain from the start of 2002 to the end of 2009. He also calculated the emissions of each different type of generator by examining government data showing their average annual fuel use. Finally, he took these two sets of data to calculate the emissions rate that should be attributed to a small change in electricity demand.

The results show that, for 2002-09, the carbon dioxide emission rate for estimating the effect of a small change in electricity demand is 0.69 kilograms of carbon dioxide per kilowatt hour of electricity consumed. This is 30 percent higher than the average emissions rate across all power stations, which is 0.51 kilograms of carbon dioxide per kilowatt hour, and 60 percent higher than the figure currently used by government advisors, which is 0.43 kilograms of carbon dioxide per kilowatt hour.

Professor Sir Brian Hoskins, Director of Imperial's Grantham Institute for , said: "This is a very important study that could help policy makers make more informed decisions to reduce our carbon emissions. The government needs a good understanding of the figures it uses to support policy analysis, because this has a big impact on which technologies we employ to reduce our energy use. With a more accurate picture of what is going on, we will be much better equipped to tackle our ."

Explore further: U.S. greenhouse emissions up 1.7 percent

More information: Paper: dx.doi.org/10.1016/j.enpol.2010.05.053

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1.3 / 5 (4) Jun 30, 2010
Amazing, but still not as effective as eliminating the top 1% of the worlds richest entities. They are the ones who consume the most resources and cause the most destruction. They command the processes that destabilize nations and damage ecosystems, and are now assimilating the remaining wealth of the world.

It's people like Al Gore and his wealthy backers who gobble it up, all the while telling the middle classes and the poor to sacrifice more and more of what little they have.

The masters at the top of the green mystery pyramid demand that we pay more and take less while they take more and give less.
1 / 5 (3) Jun 30, 2010
Listen, I could care less about meaningless metrics (such as the evil CO2 weight per KW). Give me % of my energy bill savings I'll get if I follow your "clever" methods. Oh, it is less than 1%? Oh, dear, I could save vastly more by switching from electric to gas drier, and to energy star appliances.
1.3 / 5 (7) Jun 30, 2010
CO2 is plant food, a good thing. It has had virtually no effect on temperature.

If you want to reduce CO2, switch to natural gas for heating and cooling. Using electricity is very inefficient because half of all electicity is lost in transmission. Heating, cooling, clothes drying, water heating, and cooking should all be done with natural gas - they now consume 45% of all US electricity, even though 52% of American homes already use natural gas for heating. Natural gas power costs 1/3 as much as electricity.
5 / 5 (5) Jun 30, 2010
Your information is inaccurate.

Whether humans contribute the most to climate change can be debated (though most respected scientists believe so), it is not debatable whether CO2 warms the planet. It has been demonstrated in Earth's geologic history, as well as on other planets.

You are accurate that switching to nat gas for heating will reduce CO2 emissions as long as most elect is generated by nat gas, coal, or oil. This is because the waste heat during elect production is essentially captured as useful heat when used for heating at the point of use. Cooling on nat gas is very unusual. If we are ever lucky enough to produce most energy with nuclear/wind/solar/hydro, this will no longer be true.

Again you are seriously misinformed to think half of elect is lost in transmission. Elect plants are around 40-50% efficient in converting heat to elect, but over 90% efficient in transmitting generated electricity from the plant to the home.
3 / 5 (2) Jul 01, 2010
heavy industry and commercial sector are the biggest culprits- they do not consider electrical efficiency at all or almost all forms of industrialization would be vastly different, home users are already a drop in the bucket, saving them a pittance just looks like effort.

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