Methane capture halves DCC's carbon footprint

Turning methane gas into electricity at the Green Island landfill has helped the Dunedin City Council slash its carbon footprint in half.

Figures released by the council yesterday showed its carbon emissions had been cut by an estimated 56% in two years, from 71,231 tonnes a year to about 31,000 tonnes a year.

Council finance and resources general manager Athol Stephens said in a statement the landfill's methane-capturing project was the ''major'' contributor to the result, alongside efforts to cut electricity and LPG use.

Under the landfill initiative, methane gas generated by the landfill's contents was captured and used to generate electricity, rather than being allowed to escape into the atmosphere. .

However, other initiatives were also being considered to further reduce the council's carbon footprint, he said.

That could include reducing the council's use of diesel fuel and cutting back on flights taken by council staff. Dunedin Mayor Dave Cull said reducing non-renewable energy use was the key to addressing climate change, and public bodies had a responsibility to lead the way.

The initiatives would also help ensure Dunedin moved towards achieving ''energy resilience'', he said.

The council was among the first in New Zealand to measure its carbon footprint and, in October, received independent verification - from carboNZero Holdings Ltd - its emissions had been measured correctly.

''This has provided an important line in the sand by which we can measure improvements in the future,'' Mr Stephens said.


Re: Carbon release?

MikeStk asks how this qualifies as a reduction of carbon released.

The answer is "Do the maths". It's quite straightforward really.

Every tonne of landfill gas used to generate electricity is one less tonne of LPG used to generate electricity.

In other words, if for every three tonnes of carbon released it amounts to 2 tonnes of LPG and 1 tonne of landfill gas. If that entire tonne of landfill gas is captured and used for co-generation, then you've now only got 2 tonnes of carbon being used to generate electricity. Thus, you have reduced your carbon footprint.

Mr Negative

Mr Negative strikes again. The story says the methodology used has been independently verified so obviously the council has accounted for any emmisions from burning methane and they have still cut their carbon emissions by 56%. [abridged]


Full of Chlorophyll

No problem. CO2 is essential for photosynthesis.

Carbon release?

When the DCC burns the captured methane what do they do with the resulting CO2?

I suspect they release it into the atmosphere - the amount of carbon being released is probably about the same, though of course CO2 is a much less dangerous greenhouse gas than methane, burning it is a good thing - still not better than releasing neither of them.

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