Increased renewable capacity in post-Fukushima disaster will see Japanese thermal power generation decline to 40 per cent below 2015 levels by 2030, the Institute for Energy Economics and Financial Analysis (IEEFA) said on Tuesday.

The IEEFA report — Japan: Greater Energy Security Through Renewables Electricity Transformation in a Post-Nuclear Economy — emphasises the potential for improving national energy security through renewables, most especially offshore wind and solar.

It also forecasts that many of the 45 coal-fired power stations currently in the pipeline will not get built.

"Japan is in a position now to adopt prudent policy decisions that can attract vast capital to renewable infrastructure in support of true national energy security in a way that can materially reduce its long-term reliance on imported fossil fuels and nuclear production," said an official statement quoting Tim Buckley, IEEFA's Director of Energy Finance Studies, Australasia.

The report said energy efficiency reduces demand for electricity.

"Fundamental to our assessment is the fact that increases in energy efficiency have driven down electricity demand in Japan over the past six years and will continue to do so," said the report.

"Energy efficiency in Japan supports the expansion of renewables. Falling demand, despite the probable strong uptake of electric vehicles, creates an ideal scenario for greater renewable energy investment."

The report documents how government policies adopted in the wake of the Fukushima disaster in 2011 have favoured replacement of nuclear baseload with fossil fuel baseload — a strategy that has proven costly and resulted in lost opportunities in the development of increasingly available renewable energy.

"At stake in Japan's energy transition are issues that transcend economics," the report states. 

"Japan's very energy security is at risk. Before Fukushima, Japan had enough nuclear fuel to ensure nuclear power played an important role in long-term domestic production of electricity."

The report noted that since Fukushima and the reactor shutdowns, Japan has become deeply reliant on fossil fuel imports that has contributed to a reversal in trade balance from 30 years of trade surplus to a deficit that reached $116 billion in 2014.

The report foresees that energy productivity gains will drive down electricity demand from 1,140 terawatt hours (TWh) in 2010 to 868TWh in 2030.

With population decline limiting economic growth and Japan's world-leading energy efficiency driving further energy productivity gains, electricity demand is set to decrease until at least 2030, as it has done for the past six years.

It says Japan can meet 35 per cent of its electricity needs with renewables by 2030.

Assuming a much-needed policy push to increase solar and offshore wind capacity, and factoring in the country's probable electricity demand reduction, Japan's total renewable energy share will double to a 35 per cent share of generation by 2030.