Einstein's fridge and the Aga cooker

I hadn't known that Einstein had invented a novel type of fridge in 1930, together with Hungarian physicist Leo Szilard. I was even more intrigued to read that engineers at Oxford are reviving their elegant design, because it has no moving parts and is ideal to run on solar power.

The physics fridge uses ammonia, butane and water, rather than freons, and exploits the fact that liquids boil at lower temperatures when the air pressure around them is lower.

The green Oxford physics fridge would be low maintenance and ideal for rural locations, but it's still at the prototype stage.

The news reminded me of another kitchen appliance invented by yet another Nobel physicist: the Aga cooker was the brainchild of Swedish physicist and inventor Gustaf Dalén in the early 1900s.

He set out to make an energy-efficient, multi-purpose cooker that could be used for baking, boiling, grilling and warming, and that would need little watching or attention. Aga, by the way, stands for Aktiebolaget Gas Accumulator

What's green, and earning money?

Expect to hear more about the Danish island of Samsø which, thanks to a massive community effort over the past decade, is now self-sufficient in renewable energy.

The 4,000 inhabitants spent €54 million (raised in local taxes and investment), to install nearly a dozen wind turbines on land, and the same again offshore, plus banks of solar panels, and some biomass generators.

The scheme has been so successful it is selling electricity to the mainland and generating an income for the locals -- albeit about €68 per household a year.

Shows what can be done. Looks pretty idyllic too -- we predict a boom in ecotourism there.

Irish firm makes CleanTech top 100

An interesting list of the 'companies of the future' has just been published by the Guardian and Library House. It spotlights 100 private firms around the world working to develop new clean, renewable and sustainable technologies.

Interesting to see Irish firm OpenHydro tipped among the 100 hottest to watch.

The Dublin company, one of only a few picked out in the marine power section, was selected for its innovative turbine design. This is already generating power off the Scottish Orkney Islands, and the four-year-old company plans to be the first in Britain or Ireland to produce tidal power for the National Grid.

The full 100 listing makes for interesting reading -- as might be expected, rather a lot of German companies listed, but also quite a lot of British firms (surely not a national bias there?!)

Do you count your carbon?

If you knew a product's carbon footprint, would it influence what you buy? Could carbon-labelling help reduce a country's greenhouse gas emissions?

Tesco and other British high street multiples are introducing carbon labelling on selected products, and the Japanese government recently announced something similar.

But, I'm not convinced that this carbon labelling will work.

First, counting carbon (and the other greenhouse gases) isn't easy: accurate calculations are difficult to come by, and specific to each context (change what you feed the chickens on a particular farm, and the carbon count for the supermarket chicken korma dinner changes dramatically). Then, there is the problem of what to include -- only carbon? Other greenhouse gases? And how do we take account of the 'virtual water' contained in products?

Food product labels are already littered with data (calories, 'nutritional' information, and 'may contain nuts' allergy warnings . . .) and at a time when shoppers are probably most interested in what something costs.

Printing calorie information on food products hasn't exactly stemmed the rise in obesity. And if we can't as a nation manage a lo-cal diet, what chance for a lo-CO2 one? Meanwhile, Tesco has just announced a big drive to introduce yet more cheap ranges of low-cost products. Guess we can say goodbye to the organic aisle.

Hotel towels and 'green wash'

Hotels worldwide have cottoned onto the benefits of not changing guest towels every day. Usually, there is a sign inviting us to join them in doing our bit to help the environment.

But are they really helping the environment? Or hoping to save money on their laundry bills?

I've been pondering this since reading about how hotels can make their 'towel reuse signs' more effective by wording them carefully. You can read about the study in the enjoyable and generally thought-provoking book Yes! 50 secrets from the science of persuasion.

Sure, less laundry is 'a good thing' -- it translates into less water wasted, less energy and detergents used, and less linen trucked around the place. But let's have a little honesty here.

I have yet to see a hotel announce that, thanks to guests reusing their towels, the company saved €xxx on its laundry bill last year, which it donated to a named environmental charity*, and with your help they'll save, or 'raise', even more this year.

Now, that's a wording that would really convince me not just to reuse my towels -- but even bring my own.

*With the receipt displayed proudly in the hotel lobby

Motoring tips from Ryanair?

It's not often we agree with Ryanair's environmental strategies. And no, we don't know about the safety implications of asking pilots to carry at most 300 kg of extra fuel (nothing about it on Ryanair's news page, so here's an Irish Times report).

But carrying extra fuel adds to the weight of any vehicle, so it makes fuel-efficiency and environmental sense to carry as little as possible. Which is why motorists should take Ryanair's recommendation on board.

Driving with a tank full of petrol means you get fewer kilometres per litre when your tank is full, it costs you money, and your car produces more pollution for every mile that you drive.

If the price of petrol dropped after, say, the first 25 litres, then it might make sense to bulk buy. But it doesn't. Instead, your fuel efficiency drops. Put another way: bulk buying is costing you money. Better to half-fill the tank instead.