Skip to content

The green, green gas of home

Updated Thursday 3rd April 2008

A biogas plant used in a home in Kerala, India, can teach the west some lessons about sustainability.

Some 50 metres from my hotel with its blue-tinted mirrored solar protection glass is a smart, two storied detached house surrounded by a garden with a lawn, trees, tomato plants and ornamental bushes. This is the sort of home that in the UK would easily cost upwards of £500,000. The gated driveway protects the garden from the cows that, as with anywhere in India, mingle with the traffic. However, unlike most cities and towns in India the tarmac street outside is free of litter - no plastic, no discarded food waste rotting in the sun.

I am in Kerala, a rich state in the southwestern edge of India. Kerala’s wealth is centuries old and based on the spice trade. Here black pepper, cardamom, tapioca, cashews, cloves, nutmeg, cayenne pepper, coffee, cocoa and tea are produced in abundance alongside bananas and coconuts. People here eat well and, unlike many parts of India, they have fish and meat in their diets.

Alongside this affluence Kerala is a “green” state. Road signs urge care for the environment, protection for wildlife and celebrate organic produce. There is legislation to restrict the use of plastic and everywhere bags made from hessian or coconut fibre are available. This is a state where “low tech” solutions are a matter of lifestyle choice and not necessity.

A prime example of this is the biogas plant in the garden of the house near the hotel. The unit costs a total (parts and labour) of around 6000 rupees (£75) and, by eliminating the need for bottled gas derived from fossil fuel, pays for itself in just over two years. Kitchen waste is fed in at one end along with waste “grey” water from washing food, clothes, etc.. Liquid fertiliser used for the garden is produced at the other end. A large reservoir floating over the digestion tank collects the methane produced as the organic material is “eaten’ by methane-producing bacteria.

A domestic biogas plant viewed from the waste entry point, showing the reservoir and gas pipe. Copyrighted image Icon Copyright: Bob Spicer
A domestic biogas plant viewed from the waste entry point, showing the reservoir and gas pipe

This reservoir is weighted down with a small concrete block to produce the pressure that drives the gas through a flexible hose to the kitchen. There is no unpleasant smell either in the garden or the kitchen. The methane, which is a greenhouse gas some 23 times more potent than carbon dioxide and which would otherwise vent to the atmosphere, burns with a pale blue smoke-free flame in a conventional stove and produces carbon dioxide and water vapour free of toxins.

Clearly everybody wins with this system. Organic waste is disposed of without littering the streets or requiring collection, and the garden is fertilised leading to more vigorous plant growth and carbon dioxide capture. The lack of rubbish leads to low rodent and other pest populations. There are no transport costs, carbon or otherwise, in delivering the gas or removing the waste, and above all the energy is free. No wonder that most houses in Kerala have such a system, a system encouraged by the State Government. Perhaps if we in the so-called developed world were to follow India in this instance we too would be financially and environmentally better off.


For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?

Other content you may like

Environment: Treading lightly on the Earth Copyrighted image Icon Copyright: Used with permission free course icon Level 1 icon

Nature & Environment 

Environment: Treading lightly on the Earth

This free course, Environment: Treading lightly on the Earth, focuses on the problem of greenhouse gas emissions, especially carbon dioxide, and explores what you can do to lighten those emissions to help reduce the rate of climate change.

Free course
15 hrs
Beware: cleaning in progress Copyrighted image Icon Copyright: The Open University video icon

Nature & Environment 

Beware: cleaning in progress

From COP15: With years of experience in the business sector, Mahua Acharya talks about how she helps to promote renewable energy, clean technologies and sustainable development.

5 mins
We fell in love with a catastrophe Copyrighted image Icon Copyright: Joe Smith audio icon

Nature & Environment 

We fell in love with a catastrophe

Joe Smith explains the need to move away from catastrophe narratives when discussing climate change, and looks for something more positive to inspire the public.

30 mins
Nature on the balance sheet Creative commons image Icon NASA Goddard under CC-BY under Creative-Commons license audio icon

Nature & Environment 

Nature on the balance sheet

Are we losing nature by not putting enough value on it? Monty Don asks Tony Juniper and Bill Adams in this extended interview from Shared Planet.

15 mins
Bird flu Copyrighted image Icon Copyright: Lisavan | article icon

Nature & Environment 

Bird flu

Amidst a snowfall and fears of bird flu Spring is beginning to make its presence felt.

Humans better at rapid change than we think Creative commons image Icon "León, 10 de abril de 2014" by Raúl Villalón, via Flickr under Creative Commons BY-NC-ND 4.0 license article icon

Nature & Environment 

Humans better at rapid change than we think

A new study provides evidence that humans are capable of radically altering the world around us, and offers hope in the face of climate change

Karen Mitchell: Marine campaigner Copyrighted image Icon Copyright: Karen Mitchell article icon

Nature & Environment 

Karen Mitchell: Marine campaigner

Karen Mitchell explains her role as Marine Campaigns Major Project Manager, with Natural England

Last Gasp Copyrighted image Icon Copyright: Production team article icon

Nature & Environment 

Last Gasp

Jonathon Porritt offers his opinion on the prospects for the environment

Do our clothes shopping habits require retail therapy? article icon

Nature & Environment 

Do our clothes shopping habits require retail therapy?

Many of us are culprits when it comes to buying more clothes than we can possibly wear, but what harm could it do? Guest author Natalie Dukes explains her research into female attitudes towards the notion of buying fewer garments for sustainability.