Opponents of nuclear energy say the case for nuclear power underestimates its costs and unique risks, including the fact that no other energy source can produce the sudden devastation of a nuclear meltdown. And they say that nuclear proponents overstate the challenge that renewable energy faces in replacing fossil fuels.

But while investment in renewable sources is crucially important to meet new energy needs, nuclear power remains the cheapest and most readily scalable of the alternative energy sources. Difficult as it may be to reduce dependence on coal, nuclear power is probably the world’s best shot.

Take the Energy Information Agency’s estimate of the cost of generating power. The agency’s number-crunchers include everything from the initial investment to the cost of fuel and the expense to operate, maintain and decommission old plants. Its latest estimate, published earlier this year, suggests that power generated by a new-generation nuclear plant that entered service in 2018 would be $108.40 per megawatt-hour. (A megawatt-hour is enough to supply an hour’s worth of electricity to about 1,000 American homes.)

This is not cheap. Even if the government were to impose a carbon tax of $15 per metric ton of CO2, a coal-fired plant would generate power at $100.10 to $135.50 per MWh, depending on the technology. Plants using natural gas could produce electricity for as little as $65.60 per MWh, even after paying the carbon tax.

Still, nuclear power is likely to be cheaper than most power made with renewables. Land-based wind farms could generate power at a relatively low cost of $86.60 per MWh, but acceptable locations are growing increasingly scarce. Solar costs $144.30 per MWh, the agency estimates. A megawatt-hour of power fueled by an offshore wind farm costs a whopping $221.50.

Even these comparisons underestimate the challenges faced in developing wind and solar power on a large scale. They might be clean and plentiful sources, but they require expensive transmission lines from where the sun shines and the wind blows to where the power is needed. Moreover, the sun doesn’t shine at least half the time. The wind doesn’t always blow. And we don’t yet know how to store electricity generated on hot summer days to use on cold winter nights.

The sun has provided half of Germany’s power on some days. On others it has provided next to nothing. It’s not easy to build a power network, let alone an economy, on the basis of such an unreliable energy source.