THE DEMOCRATS’ takeover of Richmond promised to bring action on big problems Virginia Republicans had played down or ignored — such as climate change. Now, as the legislature approaches key deadlines, a group of lawmakers has teed up a major global warming bill: the Virginia Clean Economy Act.

Introduced in December, the legislation came under immediate attack from left-wing activists who questioned its reliance on market-based — that is, cost-effective — mechanisms to cut carbon pollution. In fact, the bill is not perfect, but for the opposite reasons these critics suggest. It should rely more, not less, on market mechanisms.

On the plus side, the bill commits the state to eliminating power plant greenhouse-gas emissions by 2050. It would demand that utilities invest in efficiency programs, which reduce emissions with relatively little effort.

The bill would embrace the Regional Greenhouse Gas Initiative (RGGI), a program among Northeastern and Mid-Atlantic states that caps their emissions by putting an effective price on releasing carbon dioxide into the atmosphere. This discourages dirty energy and encourages clean, automatically, without the government choosing among technologies or projects. Participating in RGGI would also raise state revenue, which the bill would drive into more efficiency programs for low-income people and into preparing the state for the effects of climate change. Hampton Roads is literally sinking into the ocean; adaptation money is badly needed.

Aside from some smaller details, those two planks — efficiency and a carbon price — should be enough. Policymakers could put a price on greenhouse-gas emissions, set it to rise steadily and then watch businesses and consumers wring carbon dioxide out of the economy in response to the price signal.

Unfortunately, the bill doesn’t stop there. It would command Virginia utilities to derive increasing amounts of electricity from renewable sources. The plan prescribes specific amounts for offshore wind, small-scale renewables projects such as rooftop solar, and other technologies. Yet if the state’s emissions are to be capped and eventually eliminated, the legislature does not need to specify how. Such central planning likely will raise costs to Virginia consumers with no additional environmental benefit.

Moreover, the renewables mandate discriminates against a carbon-free power source: nuclear. Though the plan would not penalize existing nuclear power plants, which provide about a third of the state’s electricity, it also would give utilities no credit under its renewables mandate for carbon-free electricity from any new reactors.

If the state can most cost-effectively achieve net-zero emissions by 2050 without installing a single rooftop solar panel or offshore wind turbine, fine. The environmental crisis would have been addressed, and Virginians would not have over-paid for it. If new nuclear plants prove too expensive to compete against renewables, also fine — but if innovative nuclear technologies end up bringing down costs, there is no reason state policy should disfavor them. State policy should encourage the fastest, cheapest transition.

Virginia should have a strong climate program. The Virginia Clean Economy Act provides a template to establish one. Remove some of the unnecessary provisions, and it would make the state a national leader on climate policy.

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