Thursday, October 17, 2013

Powerful land fill - it's a gas!

This is a guest post from Terry Casey

On what will almost certainly turn out to be the last hot sunny Sunday this year - especially comparing it with last weekend - we ventured down to Wat Tyler Country Park at Pitsea. It's quite a few years since we were last there and there have inevitably been a few changes.

The aging row of craft units - which were rarely open, anyway - seem to morphed into a state of total dereliction, so we didn't investigate any further but there is some interesting new signage and a brand new visitor centre - the Wat Tyler Centre - and a Green Centre, with explanations of the history of the site, which was originally an explosives factory - hence its remote location! More recently it became a dumping ground for vast amounts of excavated soil from the Olympic games construction sites - this has been used to re-contour the surrounding land.

However, this is only the latest example of the area being used as a dumping ground: the area to the east of the site being used for land reclamation and then waste dumping over the years - in other words, land fill. This is changing yet again and the area is being returned to nature and is expected to become part of the Country Park itself in 2016.

Mention of land fill inevitably brings to mind the production of methane, and the Pitsea site is no exception, but here it is being put to good use.

The land fill site is first prepared with an impervious base and then, as waste dumping takes place, each day's waste is covered with a layer of clay. As the site grows, it creates a large mound. When dumping stops, it is grassed over as the first stage of returning the land to nature.

Then bore holes are made from the top of the mound right through to the bottom and perforated tubes are inserted to collect the methane. As methane is heavier than air, slight suction is needed to bring it to the surface from it is then piped down to ground level at an adjacent site. The gas is then collected together and used to produce electricity.

This shows the basic principal:


More information on the process can be found here.

The Pitsea site has an installed capacity of 11.2MW which adds up to about 100,000MWh over the course of a year - if you want to compare this with your leccy bill, it is a hundred million units a year ...
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Editor: The thing about methane is that it is a much more powerful greenhouse gas than CO2. And I believe we have one or two landfill sites here in Redbridge. Something that perhaps, the Environment Services Committee should be looking at in view of the Council’s Carbon Reduction programme, maybe?

5 comments:

  1. all adds to the pitsea pong then?

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  2. Makes one wonder how much money Dedbridge might have lost by developing a so-called golf course at Fairlop Waters rather than exploiting the methane produced by the landfill of the 1960s.

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  3. our pet name for the area could have been the Fairlop fumes I like the idea a lot but not sure if the smell would be good for the area.....

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  4. Parts of Hackney Marshes landmass, among many other similar sites and places - were built up this same way. It was originally a true marsh, but was extensively drained from Medieval times, and rubble was dumped there from buildings damaged by air raids during World War II. Otherwise Hackney Marshes in particular would be 10ft lower in many places, the entire mass of football pitches, the biggest of its kind in Europe, lay on top of all this waste, - yet all the methane produced over the decades was just allowed to escape into the atmosphere and via the pipes that are deeply embedded into these "land fill's" and utter madness as to why it's "always" been that way!

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  5. oh! and as a kid when I used to go watch me dad play I always thought it was the sunday footballers that smelt that way especially after a heavy Saturday night.

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