Change Alley

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Posts Tagged ‘salt

Green Light For London Desalination

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Boris Johnson paddling a coracleLondon’s new Mayor, Boris Johnson, has dropped a legal challenge to Thames Water’s proposed £200 million desalination plant in Beckton, East London. The High Court challenge was initiated by his predecessor, Ken Livingstone, on the grounds that the project was inefficient and bad for the environment.

Mr Livingstone said cleaner, cheaper and less wasteful alternatives should be found to avoid the “energy-guzzling and carbon-intensive” way the plant was run. According to Times Online, Boris Johnson withdrew the case after Thames Water “promised to introduce a series of environmentally-friendly measures”.

The plant will use reverse osmosis to remove salt from river water. Osmosis occurs between two solutions of different concentrations or strengths. A very fine membrane separating the solutions allows liquid (but not the dissolved solids) to pass from the weak solution to the strong solution.

Over time, the concentration of the two liquids will balance out but pressurising the stronger solution can stop the flow. If the pressure on the stronger solution is increased further the osmotic process is reversed and the liquid passes from the stronger solution making it more concentrated. This reverse osmosis process can be used to remove water from a saline solution (i.e. brackish water) thus providing a desalination technology.

The first reverse osmosis water treatment plant was built in California and started working in 1965. The nice thing about this technology is that it’s highly scalable, suitable for large projects like Beckton, producing enough water for 400,000 homes, right down to small-scale devices like Red Button Design’s ROSS (‘Innovate or Die‘)

According to Thames Water’s FAQ page, the process will be timed to extract water during the three hours leading up to low tide, minimising the salt content to less than one-third that of seawater. This means that the plant will use approximately half the energy required to treat pure sea water, and around 15% of that used by the most energy-intensive thermal desalination plants.

The plant “will use around 6.3MW a year over a 25-year lifespan”. Hmmm, not sure what that means, someone doesn’t know the difference between a megawatt and a megawatt-hour it seems. More work needed, must try harder. Thames Water have “given a legally binding commitment that 100% of the plant’s energy needs will be met from renewable energy”. Options being considered are wind power, and used cooking fat and oil. Initially, however, the plant will be powered by biodiesel, which raises the old questions, where will the biodiesel come from, and what environmental damage will be caused in producing it? I bet it’ll have some palm oil in it.

Interesting how the word ‘sustainable’ doesn’t show up in Thames Water’s information on the plant, it’s all about ‘renewable’ energy, which is more difficult for the green lobby to take exception to. They’re learning.


Written by Pete Smith

May 13, 2008 at 10:12 am

Eat Food

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Channel 4’s food season ‘Big Food Fight’ is about to start its second week. I’ve deliberately avoided most of the programs so far, because I know a lot of this stuff already and frankly I just get upset by yet more gory details about factory farming. Great bloke though Hugh Fearlessly-Eatsitall seems to be, I don’t need to sit through his faithful reconstruction of an intensive chicken farm. Although anyone who has cooked and eaten both roadkill and human placenta paté deserves our respect.

Be that as it may, last Thursday I found myself watching ‘The Truth About Your Food’, a Dispatches documentary about the £5 billion UK market in premium foods and ready meals that claim to be healthy and nutritious. Three families were given different collections of ‘foods’ from which to assemble their regular diet: premium ‘healthy’ products, e.g. Sainsbury’s ‘Be Good To Yourself’ range; bargain basement equivalents; and I can’t honestly remember what the third, quite health-conscious, family had, it may have been business as usual. That must have made them the ‘control’, although that would imply a level of scientific rigour for the program that it didn’t really deserve.

Between domestic reaction shots (“Mmmm, this is…. quite nice”) and nutritionist talking heads, we learnt a few things.

  • Foods that claim to be good for you very often aren’t.
  • Premium-price healthy products are often no better for you than their cheaper cousins, and sometimes worse.
  • The various competing food labelling schemes are confusing and pretty much useless, since people who don’t have time to cook their own food tend not to have hours to spare to decypher the figures on the packet.
  • Breakfast cereals are full of salt and sugar.
  • Concentrated fruit juices are full of citric acid which is as bad for your teeth as fizzy drinks.

And so on. I know that by the end I was past caring what the ‘results’ of the ‘experiment’ were. Each family was shown piles of salt, sugar and fat equivalent to what they’d consumed while on their ‘diet’. The relative sizes don’t matter, they were all scarily large. The one thing I took away from the program was recurring nausea at the thought of yet another Tesco chicken tikka massala or Waitrose chicken filo parcel. Chicken seemed to crop up quite often as an ingredient. I wonder where it comes from. My mate Hugh could probably tell you.

A feeling gradually emerged from all this that what these people were being fed wasn’t really food at all, but what Michael Pollan would call “foodlike substances”. In his book ‘In Defence of Food: The Myth of Nutrition and the Pleasures of Eating’, he describes how our eating habits have been formed, manipulated and controlled by a “nutritional industrial complex”. We have moved away from traditional food cultures where what we eat and how we eat it was determined by family influence and local ingredients, to a complacent acceptance of interference in our diet by scientists, marketing and governments. While nutritional recommendations change regularly, the end result is still that “much of the nutritional advice we’ve received over the past fifty years has made us less healthy and much fatter”.

So, what to do? Pollan’s core message is that we should return to eating “real food”, and offers some recommendations on how to find it and get the most out of it. It’s a long list, here’s a few to give you a flavour:

  • Don’t eat anything that your great-grandmother wouldn’t recognise as food. Going back several generations enables us to avoid the confusion of lengthy ingredient lists, most of which have dubious nutritional value and are included more for the food industry’s benefit than for ours.
  • Avoid food products that make health claims on the package. Anything with a package is more likely to be a processed than a whole food. And the whole issue of packaging and its environmental impact is another kettle of worms altogether.
  • Cook – and, if you can, plant a garden. Creating your own food chain, “from fork to fork” as Monty Don used to say, enables us to reclaim control from industry and science.

Pollan goes so far as to say that “cooking from scratch and growing our own food qualify as subversive acts”. This puts him firmly in the same camp as relocalisation groups such as Path To Freedom. It doesn’t matter how much or how little food you can grow yourself. If you can just grow some salad on a window-sill, that’s one less nitrogen-filled plastic bag of imported salad bought. After all, as Lao-Tzu said, a journey of a thousand miles begins with a single step.

Extracts from Michael Pollan’s book ‘In Defence of Food’, including his full set of rules-of-thumb, are published on the Guardian’s web site.

Consuming passion’

‘How to get back to real food’