Turning waste to good use

Turning waste to good use

KHALEEJ TIMES 19 January 2008


USING body heat to power water heaters to heat buildings; trucks that run on chocolate and floors coated with cheese to say nothing of recycling human excrement. Bibi van der Zee looks at new ways of turning our waste to good use.


Body Heat

In Stockholm, they are going to capture the body heat generated by all the passengers at the central train station to heat water, which will be piped to the next-door office and used to heat the building.

It is an inspiration in terms of lateral thinking, but it was also done with such ease and lack of discussion and argument that it feels as if it should be contravening some obscure unitary development agreement, or some other typical obstacle to common sense. Karl Sundholm, of building managers Jernhusen AB, explains: “We were just sitting in a meeting, chatting and drinking coffee, and the idea popped up. Someone pointed out of the window to the railway station and said, ‘What about all that heat over there?’ We did a couple of drawings and that was it.”

They have finished the design stage, and are now finalising the details. Work is due to start in the autumn. The predicted cost is about GBP23,000, and they expect that it will reduce their heating bills by about 15%. “It’s not so complicated,” says Sundholm. “Just a couple of pipes and water pumps. Actually, I’m surprised no one thought of it before.”

Chocolate

Chocolate, of course, has always been one of the major forces for good in this world, so news that waste chocolate is being turned into a carbon-neutral fuel, thereby solving all our problems, should be no surprise to anyone.

Chocolate factories produce a lot of waste, equivalent to 5-10% of their total output, which usually goes into animal feed or straight to landfill. But now Ecotec, a UK bio-diesel firm, has worked out how to turn it into fuel. Biofuels from purpose-grown crops are looking increasingly problematic for the environment, whereas biofuels made from waste products are, quite simply, a good thing.

A little chocolate goes a long way, too, as Ecotec discovered when it recently powered a truck all the way across the Sahara. Alhough it took four tonnes of refined chocolate waste to power the trip, that is just a small percentage of annual chocolate waste.

Ecotec is also looking into other forms of food waste. As far as carbon neutral transport goes, nothing will ever beat your own feet, or a bicycle. But chocolate power has got to be better than any fossil fuel.

Human excrement

Fecophobia, an irrational fear of human excrement, is incredibly common in the modern world. In his cult 1995 book The Humanure Handbook, Joseph Jenkins (who gave the phobia its name) tried to get us to face up to this absurdity, pointing out that in the west we take for granted the idea that “you take your dump into a large bowl of drinking water, then flush it”. Why do we believe this to be the civilised thing to do, he asked. And what a waste. 

He went on. “Where does the flushed material go? What would happen if everyone in the world crapped in their drinking water supplies? Why doesn’t any other land mammal defecate deliberately in water? Why do we?”

Human excreta, or “night soil” as it is known is some cultures, is actually a potential goldmine, he said, calculating that if the entire world’s excreta had been turned into fertiliser for our crops in 2000, it would have been worth (using 1975 prices) $18.67bn. (It was reported this week that some farmers in Zimbabwe have started to use human excrement as fertiliser because of shortages of ammonium nitrate.) Moreover, when it is collected and sealed up so that it undergoes anaerobic digestion, it also produces biogas as a side product. Biogas can be used to fuel cooking stoves and heating systems. It can even be used to power cars.

The world is slowly coming round to Jenkins’ way of thinking. By 2010, China aims to have 50m households operating biogas systems, which harvest excreta and turn it into biogas and fertiliser. In Uganda, farmers are being taught how to make biogas using human excreta along with other organic waste, and in Sweden they already make an extra strong version, which includes biogas from rotting animal carcasses, and they even run trains on the stuff. There is no place for squeamishness in the brave new world.

Whey

You wouldn’t imagine that cheesemakers and floor contractors would have much in common, but some thoughtful food scientists have changed all that. A team at the University of Burlington in Vermont has developed a method of using whey, a waste product from cheese, as a floor covering. The whey protein is apparently a perfect binding agent, which means that it can replace the highly toxic solvents usually used in wood floor coverings.

Andrew Meyer, who runs Vermont Natural Coatings, the company that has been selling this floor covering for just under a year, has had good feedback from his customers. “I’ve had floor contractors, who have been using one particular product for many years, try this out, and they’ve said that when they finish the day now they don’t have the usual headache, or the usual agitation. There’s much less off- gassing with this product, you don’t have to move out if you want to varnish your floors.”

The farmers are happy, the environmental officers are happy, and the floors are gleaming. What more could you ask?

Road power

It is kind of a vicious circle, but at least Dutch company Road Energy Systems is deriving some benefit from heavy traffic. It has developed a road that has an asphalt layer (which is very effective at conducting heat) on top of a system of water-bearing pipes. The water absorbs heat generated by vehicles on the road surface and from the sun. It is then piped away and stored thermally until needed. It is then piped to buildings, where it is used to heat the air. There is already one system in operation that powers four office blocks in Scharwoude in the Netherlands, but whether it will be used more widely remains to be seen. --Guardian News Service