Archive for the ‘energy efficiency’ Category

Qu: Can we make our rubbish into fuel?

Friday the 29th of August 2008

Qu: Would it be possible to put waste, i.e. bio-degradable rubbish and sewage into an air-tight container, let it produce methane gas, siphon it off to cook with and power gas-fired central heating, filter off the water, and be left with compost to put on gardens?

Yes – very possible, in fact it’s already being done. It’s called Anaerobic Digestion and the process is widely used to treat wastewater sludges and organic wastes. Anaerobic digestion can reduce the emission of harmful landfill gases into the atmosphere and is a renewable energy source because the process produces a methane and carbon dioxide rich biogas suitable for energy production. Also, as the question suggests, the nutrient-rich solids left after digestion can be used as fertiliser.

So why isn’t this process used everywhere? Anaerobic digesters require a high level of technical expertise to maintain as careful control of the digestion temperature, pH, quality of input and loading rates is crucial. Because of these complexities, despite being recognised by United Nations Development Programme as one of the most useful decentralised sources of energy supply and being less expensive to run than large powerplants, anaerobic digesters are not widely used in industry. (source)

Anaerobic Bioreactors, a type of landfill, can also transform decomposing material into an energy source. By removing oxygen and pumping lechtate (water which has collected waste products from the decomposing matter) and other liquids around the bioreactor the waste produces methane, which can be collected and used instead of fossil fuels. (source)

Perhaps the most exciting and accessible use of the anaerobic production of methane from plant waste is the ‘pyrolysis unit’ – invented for domestic use in India by Ravi Kumar. A family collects waste plants, dries then and puts them into the unit’s circular casing. This casing is sealed to stop oxygen combining with CO2. A small fire is started in the central void; this heats up the plants and causes them to emit gases through small holes in the casing. The gases ignite and burn for long enough to cook dinner (about an hour). Then, brilliantly, the remaining charcoal can be raked out and used as fertiliser – what’s more the soil’s subsequent ability to lock in carbon dioxide also increases. (James Bruges – What About China?- p19)

Hope that helps, 


Qu: Are energy-saving bulbs the brightest idea?

Friday the 1st of August 2008

energy saving lightbulb

Qu: What’s your stance on energy saving light bulbs? I’ve heard several reports that they contain mercury and can be dangerous.

The media had a field day at the end of last year with some serious scaremongering regarding the dangers of energy-saving bulbs (CFL’s).

It all began when The Daily Mail picked up on a report by the Environment agency calling for a public awareness campaign to explain that the packaging of energy-efficient lighting contains small amounts of potentially toxic mercury and should therefore be disposed of with care.

The Mail ran a typically hysterical piece headlined “An energy saving bulb has gone – evacuate the room now!”

The general thrust of the article being, ‘energy-saving light bulbs are so dangerous that everyone must leave the room for at least 15 minutes if one falls to the floor and breaks.’

This is, of course, an exaggeration of the facts. Toxicologist Dr. David Ray, from the University of Nottingham, told the BBC that 6-8mg of mercury is present in a typical low-energy bulb. A pretty small amount considering thermometers, which we happily stick in our mouths, contain about 3 grams of the stuff.

Dr. Ray concludes that a smashed bulb causes little danger – but warns that this increases proportionately to consistent exposure and greater numbers of smashed bulbs. DEFRA also played down the threat to health, saying; ‘No amount of mercury is good for you, but the very small amount contained in a single modern CFL is unlikely to cause any harm, even if the lamp should be broken,’

(It’s also worth noting that strip lighting has always contained mercury – yet no-one seems to be complaining about that!)

The Mail went on to finger energy-saving bulbs as a potential source of cancer following a report by British Association of Dermatologists (BAD).

In this next distortion of the facts they claim that the ‘new’ lights (they’ve actually been around for over 30 years) “can trigger migraines, as well as dizziness, loss of focus and discomfort.” However the article goes on to say that these symptoms would only affect people already suffering from certain conditions (like epilepsy and photosensitivity). Dr Colin Holden from B.A.D. explains that people suffering from photosensitive skin conditions should be allowed to continue to use daylight (tungsten) bulbs to prevent “photosensitive eruptions ranging from disabling eczema-like reactions, to light sensitivities that can lead to skin cancer.”

Fine, those with a medical condition would obviously be prescribed the old bulbs, but that shouldn’t stop everyone else switching to CFL’s.

The real concern, the one that started this debate in the first place, is the environmental impact of disposing of the energy-saving bulbs. The Environment Agency’s call for a public information campaign acknowledges a need for greater awareness before tungsten bulbs are completely phased out. Careful disposal of the energy-saving bulbs will prevent the mercury content being released into the atmosphere. Thankfully more and more places now provide the facilities for you to drop off your used bulbs to be disposed of safely, including council refuse tips and some bulb retailers (Ikea, DIY stores etc.) and this service will become more widespread as CLF bulbs become more popular.

Besides, it’s reported that, even if everyone just threw their CFL light bulbs into the main rubbish to go to landfill, the amount of mercury entering the environment would still be less than that which currently enters the environment as a result of the production of the electricity needed to power all the traditional lightbulbs. Besides, CFL bulbs last far longer than traditional ones so there will be far less of them to throw away (source). So, no excuses, off you pop to the shops to buy your new bulbs…


Question: Electricity: No flow no go?

Thursday the 22nd of May 2008

Q: “Does leaving electric switches on with nothing plugged in waste any electricity?”

empty plugAnother question about energy use in the home… The short answer is no; no electricity is being used because there is nothing completing the circuit in an empty socket – just as a lamp plugged in and switched off uses no energy.

It’s a different matter when switch is left on and there is an appliance on standby plugged into it. Research from the Energy Saving Trust found that 75% of people in the UK waste energy on a daily basis by leaving appliances on permanent standby and leaving chargeable appliances plugged in. Even leaving your phone charger plugged in, or any plug with an LED indicator, uses energy.

The same research tells us that one in seven people believe that turning appliances off uses more energy than leaving them on standby – wrong! If you’re one of them start turning things off – it’s always the best option.

As always I’d love to hear your comments, questions or alternative answers…


Question: What makes the ‘greenest’ tea?

Wednesday the 21st of May 2008

The ‘What About China?’ Blog has been asked it’s first climate change question: 

Q: ‘Which uses less energy (and is therefore greener) to boil the water for my cup of tea? Boiling the kettle (electric) for one cup, or putting the pre-filled cup in the microwave?’ from RG

electric kettle

Thanks RG; a classic brewers conundrum…

Various governmental advisory reports, like this one from Canada, indicate that the electric kettle is most energy efficient way to make your brew. An electric kettle converts about 80% of the electricity used into energy to heat the water, while the comparable figure for a microwave is about 55%.

Besides, have you ever tried a cuppa made from microwaved water? – Urgh! Tepid and weak; microwaved water doesn’t hold heat long enough to make a decent brew. Bear in mind that both options need electricity to start with; so, to get a true picture of how ‘green’ your tea is you need to go back a few steps. If the electricity powering your appliance has been produced by a fossil fuel fired power station it is a lot more costly in terms of energy than from renewable resources. Better still to install solar hot water and use the hot water heated free by the sun to start with and save time, cost and energy! 

Let me know if you have any alternative answers or comments, 


Standby for climate change….

Friday the 9th of May 2008


…and you could be standing for some time according to an article in the BBC’s Green Room. Ann Pettifor (Exc of Advocacy International) argues that it’s all very well to switch your appliances off, change your lightbulbs to EE and make sure you recycle but that’s all just a drop in the ocean considering the rate at which we’re heading towards runaway climate change.

In ‘What About China’ James Bruges uses this story to describe the same sentiment…

‘Father and daughter are watering the garden. Father is at the tap while the girl controls the hose. When they have finished the father says, “that’s enough now, stop all the holes in the spray head with matchsticks.” “Dad,” she replies, “are you mad? Turn the tap off!”‘

The father’s stupid approach is rather like present policies where we are urged to travel less and turn our heating down a few degrees. Meanwhile world leaders are encouraging the extraction of as much fossil fuel as possible. I don’t agree that our individual commitment is irrelevant – we each have a very real responsibility to examine our habits and change them for the greener – but I do think that just plugging away in a vacuum is a bit like sticking your head in the sand.

Once out of the ground fossil fuels will be burned. The key to emissions reduction is to stop extraction at source. Unfortunately it’s the politicians who control the government’s energy policies so it’s up to us to persuade them to change.

You can make a difference in the political arena. Use your vote. Urge your politicians to put a cap on the use of fossil fuels and join the transition movement where communities work together to find a post-carbon way of living. Click here to read ‘Operation Noah’s’ practical guide lobby your local MP.


Ask a climate change question…

National Downshifting Week

Wednesday the 30th of April 2008

Making a change for the greener doesn’t have to be a mammoth effort or cost you loads of money – how about making your life easier and saving money? National Downshifting Week (NDSW) runs for 7 days from the 19th of April – don’t worry if you missed it; when you see how simple it is to make your life easier and your environmental impact less you’ll be wanting to downshift all year long.

Tracy Smith, founder of NDSW, is passionate about “slowing down your pace, finding a better work/life balance, embracing living with less and leading a simpler, greener and happier life!” Sounds great doesn’t it?

So how do we go about it? The NDSW website is full of practical and fun ideas; now the sun’s out how about starting with your garden? Try turning one of you’re sunnier beds into a vegetable patch and what about starting a compost heap? You’ll be recycling your food waste and providing nutrients for your new plants. If you’re not green-fingered what about supporting your local growers by getting your produce from them. A trip to a farmers market is great fun and you can often pick up varieties you won’t find in the supermarkets.

Look out for Tracy Smith’s new ‘Book of Rubbish Ideas’ – it’s an interactive guide to reducing your household waste, it’s published by Alastair Sawday’s and will be available in September.


Ask a climate change question…

What about China?

Monday the 28th of April 2008

Welcome to the all about what about china Blog…

What about China? is the latest in Alastair Sawday’s Fragile Earth series, it answers all those awkward questions about climate change that you’re afraid to ask and lays to rest the speculations and misconceptions that are bandied around amongst even the most well meaning individuals.

The book is laid out in a series of questions with jargon-free answers provided by a panel of experts from The Soil Association, WasteWatch, Ecover, The Centre for Alternative Technology, James Bruges (author of the Little and Big Earth Book) and Alastair Sawdays.

Topics covered include climate, recycling, energy, travel and food and this blog is your chance to ask even more questions, discuss any issues raised in the book, keep abreast of relevant current related news articles and lots more…

I’m looking forward to hearing your questions and finding out the answers…

Ask a climate change question…