We must be thankful to carbon dioxide (CO₂) and other greenhouse gases, because, these gases help to stabilise temperature level suitable for life what is known as greenhouse effect. Millions of years, our ecosystem has managed to regulate concentrations of greenhouse gases through natural sources and sinks. Carbon (in the form of CO₂ and methane) is emitted by volcanoes and by rotting vegetation and other organic matter. But CO₂ is sequestered, or absorbed, by plants and other forms of life. Some of this carbon will be released back into the atmosphere by respiration but more carbon is sequestered. However, unsustainable development practices, such as, increased use of earth resources, especially, fossil fuel consumption and deforestation emitted excess CO₂, in time it would be partly absorbed by the increased growth of forests, and partly dissolved in the oceans, leading to enhanced greenhouse effect and associated climate change. The global emissions need to be reduced from current 55 billion tCO₂e to around 20 billion tCO₂e by 2050 to stabilize the atmospheric CO₂ concentration at around 450 ppm to avoid the catastrophic change in the climate as long-term target.

In 1992, most developed countries in the world agreed to the United Nations Framework Convention on Climate Change (UNFCCC), which is designed to impose limits on greenhouse gas emissions and thus minimise the adverse effects of climate change. The objective of the Framework Convention is to achieve "stabilisation of the greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner". Latter a legally binding target was accepted under Kyoto Protocol in 1997 where developed countries agreed to reduce their emission by 5.2% below 1990 level. The Kyoto protocol introduces three co-operative mechanisms for developed countries to fulfill the commitments besides domestic actions to reduce emission. These include ET (Emission Trading) and JI (Joint Implementation) between developed countries and Clean Development Mechanism (CDM) between developed and developing countries.

Under International Emissions Trading, countries are permitted to use a trading system to help meet their emissions targets. In principle, a country may allocate permits to individual companies for the emission of a certain quantity of greenhouse gases. Permits are only issued to companies to a level equal to or below the assigned amount to meet its Kyoto commitment. If a company is not meeting its target, it can buy permits from other company that is under their targets. Carbon credits are also issued for activities, such, afforestation and reforestation where carbon is absorbed and sequestered. But it requires strict assessments like, was the forest established after 1990, how quickly it is growing and how much carbon it is sequestering. Credits are issued to the individual or company sequestering the carbon, eg. growing the forests. These credits can be sold, in international carbon market, to a carbon emitter (who is unable to meet the emission target) such as, a power company, using them to 'offset' its excessive carbon emissions.

TNPL as leader in implementing sustainable and environment friendly technology projects has already registered two CDM projects with UNFCCC (United Nations Framework Convention on Climate Change), first under waste management sector (biogas), and second in renewable energy sector (Wind Farm) to mitigate climate change and three projects are under the validation stage.

The project activity involves installation of a closed anaerobic system that will produce and collect consistently high quality methane-rich biogas from bagasse wash wastewater (BWW) generated from bagasse yard and bagasse washing area in pulp mill. The BWW is diverted from TNPL's existing wastewater treatment system, open lagoon under anaerobic conditions into a closed anaerobic digester. The project activity also includes system for utilization of the collected biogas as a fuel in a lime kiln, which was earlier using furnace oil (fossil fuel). By extracting and capturing biogas, nearly 15,000 m³ per day, in a closed digester, the project reduces the methane emission that would have otherwise been emitted to the atmosphere from open lagoons. In addition, the use of the collected biogas as a fuel in the limekiln displaces nearly 10,000 lit. of furnace oil costing around RS 30 per Lit. and its associated GHG emissions. It is a first CDM project in pulp and paper industry in the world and waste management sector in our country.

The project activity viz "Methane Extraction and Fuel Conservation Project" project of Tamil Nadu Newsprint and Papers Limited ("TNPL"), Karur District, Tamil Nadu was registered with UNFCCC as a CDM project activity under article 12 of the Kyoto protocol on 14^th January 2005. The project will reduce around 400,000 Tonnes of CO₂ equivalent and equal number of CERs for the total ten year crediting period. After completion of total 3 verifications and certification process by another third party (Designated Operating Entity), CDM EB (CDM Executive Board) of UNFCCC issued 161,956 Certified Emission Reductions for the period August 2003 to December 2007. This means that the implementation of the project, reduced 161,956 Tonnes of CO₂ and it is estimated that another 80,000 tonnes of CO₂ emission were reduced in the year 2008 and 2009 and awaiting certification from CDM EB.

The above CDM project will generate electricity using 4 X 3.0 MW WEGs and 3 X 1.25 MW WEGs in the Devarkulam wind farm. The CDM project activity has been conceived for generating green energy from the renewable wind source and to sell the generated electricity to state electricity utility (Tamil Nadu State Electricity Board) utilizing the regional grid and will be supplied to the local consumers drawing electricity from the local grid. Since wind power is GHG emissions free, the wind power generated will save the anthropogenic greenhouse gas (GHG) emissions generated by the fossil fuel based thermal power stations comprising coal, diesel, furnace oil and gas. The project was registered on 24th May 2007 and reduced 68,367 tonnes of CO₂ emission and generated equal amount of carbon credits. In the current year this project is expected to reduce around 12,000 tonnes of CO₂ emission.

Apart from the above two registered projects, TNPL is in the process of developing three more CDM project viz. 1. Energy Efficiency Improvement in Chemical Recovery Boiler, the project is expected to reduce around 1,32,000 tonnes of CO₂ emission per annum 2. Biogas projects II, the project is expected to reduce 30,000 tonnes of CO₂ emission per annum, 3. Renewable energy project i.e. 13.75 wind farm Project, the project is expected to reduce 27,000 tonnes of CO₂ emission per annum. All the three projects got approved by the Designated National Entity i.e. Ministry of Environment and Forest, Government of India. If registered by CDM EB of UNFCCC, all the above three projects can reduce around 1, 87,000 MT of CO₂ emission and generate equal amount of Carbon credits per year.