The problem with "clean" Hydro and what to do about it
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Manu Sharma
May 21, 2007, 2:32:09 AM5/21/07
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Today's Hindustan Times carries a front page report on the problem of methane emissions by India's hydro dams. Hydroelectricity, which accounts for 19% of world electricity and 63% of renewables, has long been considered a "non-polluting and environmentally benign" source of power but recent reports coming out of Brazil claim that Hydro could actually be as bad as coal when it comes to greenhouse gas (GHG) emissions thanks to methane.
The story cites the latest report released by Brazil which claims that methane emissions by India's dams are contributing as much as one-fifth of India's total GHG emissions. Hindustan Times asked all the key players in the picture for comments - R.K. Pachauri who heads the IPCC panel, Surya P. Sethi, India's energy advisor - who only last October ridiculed the notion that climate change requires changing India's policy measures and Patrick McCully who has been writing against big dams for years.
The inside pages of HT carry a full-page report on the growing climate change issue. It looks like Indian press is finally grasping the challenge posed by global warming and the government is getting lobbied into at least looking at the issue seriously rather than rejecting it outright as they have done in the past.
What Causes Methane Emissions in Hydro Dams?
The science behind the problem is pretty straightforward - all big hydro dams bring with the water a lot of vegetation to the reservoir - trees, shrubs, wooden logs etc. This gets accumulated at the bottom of the reservoir against the large wall of the dam where it rots. Since the bottom gets very little sunlight and no oxygen, the vegetation is broken down by bacteria and the accumulated carbon in it releases in the form of methane and CO2.
Methane emissions are a big problem because as a greenhouse gas, methane is 21 times as bad as CO2 in terms of trapping heat in the atmosphere. Though unlike CO2, its half life is much shorter - which means it stays in the atmosphere for far smaller duration than CO2. India's methane emissions from hydro dams are highest in the world because unlike China, Canada, Russia and US - countries that fall in the temperate region, many of India's Hydro dams are in the tropics.
How Combat to Methane Emissions in Hydro Dams?
The same Brazilian institute - National Space Research Institute (INPE) - that cited India's contribution to global greenhouse gas emissions has proposed a way to tackle this problem - capture and burn methane at the dams to produce power (note that natural gas or CNG is largely methane). Scientists at INPE estimate that some dams with a particular methane problem can increase their power output by as much as 50% through this method.
It is not clear though how environmentally sound the process is, because as you burn methane you emit CO2. However, INPE claims that the technique could lower emissions by the equivalent of a years total fossil fuel consumption in the UK. In a recent BBC report on the issue, the lead scientist at INPE said: "We cannot hide from this problem; you have to address it. In fact, it's better to recognise there is a problem today, and to use this methane that is there as a commodity, harvest it to produce energy."
- Manu
Green-India
The story cites the latest report released by Brazil which claims that methane emissions by India's dams are contributing as much as one-fifth of India's total GHG emissions. Hindustan Times asked all the key players in the picture for comments - R.K. Pachauri who heads the IPCC panel, Surya P. Sethi, India's energy advisor - who only last October ridiculed the notion that climate change requires changing India's policy measures and Patrick McCully who has been writing against big dams for years.
The inside pages of HT carry a full-page report on the growing climate change issue. It looks like Indian press is finally grasping the challenge posed by global warming and the government is getting lobbied into at least looking at the issue seriously rather than rejecting it outright as they have done in the past.
What Causes Methane Emissions in Hydro Dams?
The science behind the problem is pretty straightforward - all big hydro dams bring with the water a lot of vegetation to the reservoir - trees, shrubs, wooden logs etc. This gets accumulated at the bottom of the reservoir against the large wall of the dam where it rots. Since the bottom gets very little sunlight and no oxygen, the vegetation is broken down by bacteria and the accumulated carbon in it releases in the form of methane and CO2.
Methane emissions are a big problem because as a greenhouse gas, methane is 21 times as bad as CO2 in terms of trapping heat in the atmosphere. Though unlike CO2, its half life is much shorter - which means it stays in the atmosphere for far smaller duration than CO2. India's methane emissions from hydro dams are highest in the world because unlike China, Canada, Russia and US - countries that fall in the temperate region, many of India's Hydro dams are in the tropics.
How Combat to Methane Emissions in Hydro Dams?
The same Brazilian institute - National Space Research Institute (INPE) - that cited India's contribution to global greenhouse gas emissions has proposed a way to tackle this problem - capture and burn methane at the dams to produce power (note that natural gas or CNG is largely methane). Scientists at INPE estimate that some dams with a particular methane problem can increase their power output by as much as 50% through this method.
It is not clear though how environmentally sound the process is, because as you burn methane you emit CO2. However, INPE claims that the technique could lower emissions by the equivalent of a years total fossil fuel consumption in the UK. In a recent BBC report on the issue, the lead scientist at INPE said: "We cannot hide from this problem; you have to address it. In fact, it's better to recognise there is a problem today, and to use this methane that is there as a commodity, harvest it to produce energy."
- Manu
Green-India
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