City gas and the environment

1.Numerical targets of the gas industry indicated in the Keidanren's Voluntary Action Plan on the Environment

In the city gas production and supply stages, the CO₂ emissions intensity shall be decreased from 83.6 g-CO₂/m3 in fiscal 1990 to 10.0 g-CO₂/m3 in fiscal 2010. This means a decrease in CO₂ emissions of 1.328 million ton-CO₂ in fiscal 1990 to 450,000 ton-CO₂ in fiscal 2010.


1-1 Results of the Keidanren's Voluntary Action Plan

While Japan’s total production of city gas more than doubled between fiscal 1990 and fiscal 2008, increasing from 15.9 billion cubic meters to 35.7 billion cubic meters, CO₂emissions were significantly reduced from 1.328 million tons to 322,000 tons. Regarding CO₂ emissions intensity, 83.6 grams of CO₂were emitted in the production of one cubic meter of gas in 1990, but by 2008 this had been reduced to 9.0 grams per cubic meter, a reduction of 89 percent.

Fig. 1 Results of voluntary action plan

The CO₂ emissions and intensity have been compensated for giving due consideration to the contribution of CHP. This compensation involves considering the contribution of CHP in reducing the consumption of grid power by the use of the Marginal Emission Factor (MEF), that is, the emission factor for thermal power plants whose operation is thought to be responsive to demand fluctuations. This allows the evaluation of a certain amount of reduction in CO₂ emissions that is not considered by the conventional calculation method based on the average emission factor for all types. This additional reduction in CO₂ emissions is subtracted from the AEF-based estimation of the total CO₂ emissions.


1-2 Implemented measures

We are making efforts to reduce CO₂ emissions by converting gas sources to natural gas and by implementing energy conservation measures at gas production facilities.

(1) Improvement of city gas production efficiency by switching to the LNG gasification process

The city gas industry is switching its gas sources to natural gas with high gas production efficiency of over 99 percent from coal, which has a gas production efficiency of 70 to 80 percent, and oil, which has a gas production efficiency of 85 to 98 percent.

(2) Promotion of various energy conservation measures in city gas producing facilities

We are promoting a variety of energy conservation measures, including:

• Installation of highly efficient equipment
• Expanding the cryogenic use of LNG
• Power generation and efficient use of exhaust heat by cogeneration
• Improvements in plant operation