Archive for the ‘green’ Category

Green tech: Reusable washing enzymes

Friday, September 7th, 2007
Enzymes that catalyse the breakdown of proteins and carbohydrates have long been added to washing powders to help remove stains from clothes and crockery at low temperatures. But these enzymes dissolve and break down during a wash and may be attacked by other components of washing powder, such as alkaline cleaning agents, rendering them useless.

Since enzymes could, in theory, be used again, the way they are currently flushed down the drain after one use is very wasteful, says the German washing machine and dishwasher maker Bosch.

The company has come up with an alternative approach. It involves using enzymes during periods of a wash when the alkaline cleaning agents are not present and also preserves them for reuse. The trick, says the company, is to encapsulate the molecules in a polymer membrane that is permeable to washing liquids but impermeable to water. This allows them to carry out their job of catalysis without dissolving.

The polymer capsules are not added to the washing powder, but are instead held in a hollow container in separate part of the washing machine through which water is flushed during appropriate parts of the washing cycle. In this way a variety of enzymes for attacking different stains can used and reused wash after wash.

Read the full reusable enzymes patent application.

Justin Mullins, New Scientist contributor

Posted in environemnt, enzymes, green, laundry, washing | Comments Off

Green tech: Capturing CO2 from coal burning

Friday, September 7th, 2007
Reducing CO2 emissions from coal burning is an important priority, says Morris Argyle in the Department of Chemical and Petroleum Engineering at the University of Wyoming. He also suspects that removing CO2 from flue gases may be easier than previously thought.

Argyle says CO2 can be absorbed by fly ash, the residue left over after coal burning. In tests where carbon dioxide was bubbled through a fluidised bed of fly ash for 15 minutes, the ash absorbed up to 4% of the gas passing through.

His suggestion is that CO2 could be regularly sequestered from flue gases by passing exhaust fumes through such a fluidised bed of fly ash. The resulting waste could then be buried.

It looks like a very simple way to reduce emissions, especially since the ash has to be disposed of anyway. But how stable is the carbon dioxide once it is absorbed by fly ash? It would be no good burying the ash only to find the carbon dioxide leaking out over the next few years.

See the full CO2 capturing patent application

Justin Mullins, New Scientist contributor

Posted in CO2, carbon-dioxide, environemnt, green, pollution | Comments Off

Green tech: Faster biodiesel production

Tuesday, September 4th, 2007
Making biodiesel involves a reaction called transesterification in which the triglycerides and free fatty acids in oils from plants such as corn or linseed react with methanol to form methyl esters of 16-18 carbon atoms in length. Purified methyl esters can then be used in place of diesel fuel.

The problem is that transesterification is a slow process and currently the only way to speed it up is to cook chemicals in batch reactors at high temperatures and pressures. But having to produce fuel in batches also limits the rate at which biodiesel can be made.

Now Christian Fleisher and colleagues at Cornell University have developed a way of making biodiesel continuously, without the need to fill and empty batch reactors.

The trick is to produce the transesterification reaction as the necessary chemicals mix and flow through a pipe. The result is a system – known as a "plug flow" reactor – in which plant oil and methanol is added continuously at one end, while biodiesel flows out of the other.

Fleisher achieves this speed increase by using a catalyst, such as sodium hydroxide. So, instead of taking hours, the transesterification reaction then takes place in under three minutes. Fleisher has even set up a company called Biodiesel Technologies to commercialise the idea.

See the full continuous transesterification patent application.

Justin Mullins, New Scientist contributor

Posted in bio-diesel, biofuel, energy, environemnt, green, pollution | Comments Off