Japan has come up with a plan to strengthen its power grid by significantly expanding the use of renewable energy. It envisions total investments of around 50 billion dollars by 2050.

Japan is working toward a carbon-free society. It considers solar, wind and other renewables a major component of this. Building a cross-regional power transmission system is essential to the effective use of renewables.

The plan was drawn up by an industry body made up of large and small utilities, energy-related companies, and different levels of government. Its mandate is to coordinate power transmission across Japan's different regions.

The plan assumes renewable energy will account for around 50 percent of the country's total energy mix by 2050. It says a new transmission network is needed connecting Tokyo and the northern regions of Tohoku and Hokkaido, home to many solar and wind plants.

The plan also suggests power transmission lines connecting western and eastern Japan need to be improved.

It estimates a total of around 6 to 7 trillion yen, or about 50 billion dollars, should be invested in these projects by 2050.

The ministry of economy and industry says it will begin consultations with power companies and other entities to work out the specifics, and determine how to cover the costs.