Waste heat is energy that is lost from a process. Could be the cooling tower of a power station or factory, or the exhaust of a big engine. Usually the problem is the temperature is on the low side and so the heat is not considered worth recovering.

So the heat that is rejected has been paid for in the process. The reject heat is considered valueless and sometimes even a problem to be got rid of.

But the Arab states recover this heat and use it to desalinate seawater. This is possible because MSF desalination processes can utilise low grade heat.

The Arabs call this "co-generation" - the production of both electricity and

fresh water from the same fuel. Maybe the water is not quite "free" but it is a long way ahead of what we are capable of - and the really sad thing is we don't even understand how far behind we are.

Waste Heat Desalination
In a similar way Alfa Laval freshwater generators can utilise the waste heat available from installations such as drilling rigs, offshore platforms and ships for fresh water production.

That is, the cost of the power to operate the desalinator is zero.

This photo shows a

medium sized vapour compression distiller that can produce up to 25,000 cubic metres of fresh water a day, or approximately the daily consumption of the city of Toowoomba (25 Megalitres a day).

Engine Powered Desalinator
Here's a small one - it stands about 2.5m high, a little bigger than a man - and it's output is 40m³/24hrs, or about 40,000 litres a day.

And it is powered by the cooling water from a medium size diesel motor!!!

Heat that was going to be thrown away.

Why the hell would we be considering building nuclear power stations to generate electricity so we can drive Reverse Osmosis desalinators?

And for those who can't accept that the Arabs might be light years ahead of us in water handling, this machine is manufactured in Sweden - a country famous for their design skills.