Environment Ministry endorsement has been withheld on plans to build three large coal-fired power plants in succession due to fears that such plants endanger Japan's commitments to cutting its greenhouse gas emissions. The Ministry of Economy, Trade and Industry is meanwhile reportedly considering a cap on the proportion of coal in power companies' generation of fossil fuel-based electricity. The government and the power industry should rethink their emphasis on coal as a cheap alternative to nuclear energy in view of the impact on the nation's efforts against climate change.

Japan stands out among major industrialized economies in its promotion of coal as a key source of electricity generation. As the power companies rely heavily on imported fuel to run their plants due to shutdowns of most nuclear power plants since 2011, they are keen on the greater use of coal because it is less expensive than natural gas. However, coal-fired plants emit more carbon dioxide than liquefied natural gas (LNG) per unit of power generation.

It's an energy source that many other countries are trying to rely less on in their effort to cut the output of global warming gases.

According to a tally by the environment group Kiko Network, there are currently plans to build 48 new coal-fired thermal power plants across Japan, with a combined output capacity of 23,500 megawatts. These include plans with participation by companies outside of the power industry in view of the April 2016 deregulation of electricity retail. An increasing number of the planned installations are small plants with an output capacity of less than 112.5 megawatts each — which does not require the national government's assessment of its environmental impact for the official permit for its construction.

The three plants for which Environment Minister Yoshio Mochizuki has since June effectively withheld approval "at this point" in his comments on the environmental assessment process are planned for Ube, Yamaguchi Prfecture, Taketoyo, Aichi Prefecture and Sodegaura, Chiba Prefecture. Though his comments do not immediately halt the process, Mochizuki said his ministry cannot approve their construction unless the power industry comes up with concrete plans to reduce carbon dioxide emissions.

Even since before the 2011 Fukushima crisis and the nationwide shutdown of nuclear power plants, carbon dioxide emissions by the power industry have been rising, accounting for more than 40 percent of the nation's total emissions today, compared with roughly 30 percent in 1990. A coal-fired plant is estimated to emit twice the amount of carbon dioxide that an LNG-fired plant does in producing the same amount of electricity.

Japan's pledge on its climate change efforts calls for reducing its greenhouse gas emissions in 2030 by 26 percent from its 2013 levels. But the Environment Ministry estimates that, if all of the coal-fired plants being planned are built, and then would be in operation for decades to come, Japan will likely miss its emissions reduction target by 60 million tons in 2030.

In response to the environment minister's call, the power companies said in July that they would make voluntary efforts to cut their carbon dioxide emission per 1 kwh of electricity sale in 2030 by 35 percent from 2013. However, the effectiveness of the plan is in doubt since it has no binding power on what each utility should do and offers no specific measures to achieve the target.

The Abe administration, which is pushing for the restart of nuclear reactors idled since 2011, has set a forecast for the nation's energy mix in 2030. While it's assumed that nuclear power will account for 20 to 22 percent of Japan's electricity supply 15 years from now, the projected share of coal-fired thermal power plants is put at 26 percent and that of natural gas-fired plants at 27 percent.

There is concern, however, that if the restarts of nuclear plants do not proceed as hoped by the government, the power industry will rely more on inexpensive coal as the preferred source of energy. Price competition between established power firms and new entrants to the market — which is hoped to intensify with the power retail deregulation — may also drive the industry more toward coal-fired plants.

Supporters of coal-fired plants argue that constructing new, more efficient plants to replace aging existing facilities would help reduce the nation's carbon emissions. Japan in fact promotes exports of its up-to-date coal plant technology on the grounds this will contribute to decreasing overall global emissions.

But while it may be inevitable for Japan to rely to a certain extent on coal-fired plants in coming years, the plans to build more coal plants and export the technology seem out of step with other countries, such as the United States, Britain and Canada, which have tightened controls on emissions from coal-fired plants and made creation of new domestic plants effectively difficult. Moves are also spreading to stop lending by public financial institutions to fund projects in developing countries to build new coal-fired plants.

METI is reported to be weighing a new rule, to be effective as early as in fiscal 2016, that would limit the power companies' reliance on coal to no more than half of their thermal power output —a level that is currently topped by the five regional power firms that serve Hokkaido, Hokuriku, Chugoku, Shikoku and Okinawa.

The ministry hopes the rule would promote the conversion to LNG-fired plants, which are more costly but emit less carbon dioxide, and shutdowns of aging and inefficient power plants. The government should also consider other policy options, such as introduction of tighter cap on emissions on the coal plants, to control the output of greenhouse gases from the power sector.