Korea’s first nuclear reactor, Kori No. 1 in Busan, was shut down permanently Sunday, 40 years after it began operations.

It was the first step President Moon Jae-in took to move the country away from nuclear energy.

“We will abolish our nuclear-centered energy policy and move toward a nuclear-free era. We will completely scrap construction plans for new nuclear reactors that are currently underway,” Moon said in a ceremony to mark the shutdown of the reactor on Monday.

During his campaign, he pledged to close all nuclear and coal-fired power plants within 40 years. He promised to ban new reactors and expand renewable energy from the current 2 percent to 20 percent by 2030.

Last month, Moon ordered the closure of all fossil fuel power plants aged more than 30 years within his five-year term.

It is ideal in view of safety and environment to go from nuclear and fossil fuels to natural gas and renewables. But rushing the change may bring about power shortages and other side effects.

The government says it can meet demand by increasing power generation with liquefied natural gas, instead of nuclear fuel, but it is questionable if this can be done as efficiently as it is now with nuclear power.

Korea imports 98 percent of the energy it needs. It generates about 60 percent of its electricity from nuclear and coal plants.

Under Moon’s energy projection, the figure will go down to 43 percent in 2030. The share of liquefied natural gas will increase from 18.8 percent to 37 percent. Renewables will rise from 4.7 percent to 20 percent.

Late last year, coals accounted for 34.1 percent of the nation’s power generation, atomic fuels 28.8 percent and natural gas 21.5 percent.

The cost of electricity generated with nuclear fuel is 5.69 won (half a US cent) per kilowatt-hour, compared to 46.59 won for coal and 88.82 won for gas. If all nuclear and coal plants are taken offline as Moon pledged, electricity price increases will be inevitable.

Natural conditions are not so suitable for photovoltaic and wind power generation in Korea. Wind and solar energies are affected by nature and are intermittent.

More troubling than production cost is it is doubtful whether renewables could generate much of the electricity needed at industrial sites. Experts view renewable sources generating 10 percent of total electricity production by 2030 as unlikely without infrastructure to transport and store renewable energy.

If the Moon administration wants to curb carbon emissions and transition to green energy, it should first develop renewable energy.

If Shin Kori No. 5 and No. 6, two new reactors which are about 26 percent constructed, are scrapped, about 4 trillion won in sunk costs will be incurred.

The nuclear reactor Korea exported to the United Arab Emirates is the same model to the Shin Kori reactors. What will the Middle East country think of shutting them down? Exports of Korea’s accumulated nuclear reactor technology are worth considering.

Japan is operating nuclear plants, though its Fukushima plant was destroyed in a tsunami in 2011. Despite the trauma of the accident and frequent earthquakes, it decided to expand nuclear power generation to 20 percent by 2035. It had no other choice to tap nuclear energy to meet increasing power demand.

Switzerland banned new nuclear plants through a referendum last month. Germany decided not to add nuclear plants. But Switzerland generates 60 percent of power from hydroelectric stations. Germany imports electricity from France, which relies on nuclear power for three-quarters of its electricity generation.

Korea is different from these countries. It is not an oil-producing nation. It has no countries, either, from which it can import electricity.

Safety and environment are important, but economic feasibility should be considered as well. Public understanding is needed about the inevitable electricity rate hikes. An emergency situation such as an unexpected event limiting the gas trade should be taken into account.

The Moon government needs to review its energy policy from a long-term perspective and should make meticulous plans to prevent any possibility of power shortages due to going nuclear free.