Election 2020: The 2020 US presidential election is a critical moment for politics, technology and policy-making. We cover everything from secure voting systems and disinformation campaigns to the future of jobs and plans to combat climate change.

Senator Bernie Sanders, the front-runner for the Democratic nomination in this year's presidential election, has put forth the most audacious climate plan among the contenders.

But there are doubts about the political and economic feasibility of his sweeping vision, as well as the wisdom of some of his particular technical proposals. Notably, the plan restricts tools that could help rapidly cut greenhouse-gas emissions, including nuclear power and technologies that can capture carbon dioxide.

Sanders wants to pump more than $16 trillion into a version of the Green New Deal that would eliminate emissions from the US power sector, as well as all ground transportation, within a decade.

To pull it off, he wants the government to play a much larger role in the electricity sector. His plan would direct new or expanded federal agencies to build nearly $2.5 trillion worth of wind, solar, geothermal, and energy storage projects.

The plan would also force major changes on the fossil-fuel sector, including ending federal subsidies, mountaintop-removal coal mining, and the import and export of fossil fuels. He’d also direct federal agencies to investigate whether companies broke the law in covering up their role in climate change, or owe damages for the destruction they cause.

In addition, Sanders wants to invest more than $2 trillion to help families and small businesses improve the energy efficiency of their homes, buildings, and operations; and more than $1 trillion to retrofit or construct bridges, roads, water systems, and coastal protections in ways that will stand up to harsher climate conditions.

He says the plan will create 20 million jobs, while offering wage guarantees, job training, and other assistance to displaced energy workers. His broader goals for the Green New Deal go beyond climate and clean energy as well, boosting funding for affordable housing and rural economic development, and enhancing protections for civil rights, environmental justice, and labor.

Sanders says he’d immediately put the US back into the Paris climate agreement. He'd also work with world leaders to redouble efforts to prevent 1.5 ˚C of warming, the original aspirational goal of the accord. (Current commitments under the agreement would allow temperatures to rise as much as 3 ˚C, his campaign says.) And he wants to spend $200 billion to help developing nations build clean energy and climate adaption projects.

Here are Sanders’s positions on other key energy issues.

Electricity: Sanders’s plan would require renewable energy sources like wind, solar, and geothermal to provide all the nation’s electricity by 2030. To ensure the reliability of the grid as it comes to depend heavily on naturally fluctuating sources, he wants to spend more than $500 billion on modern transmission and distribution systems. He has also proposed a $30 billion research and development effort to create cheaper and longer-lasting forms of energy storage.

Vehicles: To decarbonize ground transportation in the next decade, Sanders wants to spend more than $3.6 trillion to help households, businesses, cities, and schools replace their cars, buses, and trucks with electric vehicles.

He also plans to invest $100 billion in research funding to cut the costs of electric vehicles, and $150 billion on the much tougher task of cleaning up airplanes and ships. On top of all that, he wants to spend $900 billion to expand public transit and high-speed rail, and more than $85 billion to build out a national charging network for electric vehicles.

Other industries: The proposal calls for decarbonizing all sectors of the economy, including manufacturing, by 2050.

Carbon price: Sanders’s current plan doesn’t specifically mention a carbon tax, but it does say he would force the industry to “pay for their pollution by ... massively raising taxes on corporate polluters’ and investors’ fossil fuel income and wealth.”

Fracking: Sanders wants to immediately ban fracking, a drilling method widely used for natural-gas and oil extraction. In fact, he already introduced a bill earlier this month that would phase out the practice entirely by 2025.

Nuclear: Sanders’s plan would prevent any new nuclear plants from being built, including the safer, advanced designs that numerous startups and research groups are working to develop. But he goes further, promising to enact a moratorium on renewals for existing plants, which would force them to cease operations when licenses expire.

He shuns a few other technologies in his plan as well: “To get to our goal of 100 percent sustainable energy, we will not rely on any false solutions like nuclear, geoengineering, carbon capture and sequestration, or trash incinerators.”

Feasibility and risks: The scale and expense of Sanders’s proposals will make them extremely difficult to enact. That $16 trillion dwarfs the already bold spending plans of anyone else in the field. And business interests are going to fight back hard on any bans and regulations that would ravage their bottom lines.

Then there’s the question of practicality. Immediate prohibitions on the energy sources that fuel our vehicles, heat our homes, and power our businesses, before we’ve developed cleaner replacements, would almost certainly cause major economic disruptions.

Some climate and energy researchers also worry that banning fracking, and hence limiting supplies of natural gas, could end up extending the life of even dirtier coal plants. And such a prohibition will be very controversial among voters in key election states like Pennsylvania and Ohio, where natural gas is a huge part of the local economy. 

There’s a long-running debate in the climate community over whether the US should build more nuclear power facilities or not. But beginning to shut down existing plants, the nation’s largest source of carbon-free electricity, is clearly misguided if the goal is to eliminate emissions as rapidly as possible.

Avoiding the use of carbon capture technology will also complicate matters. For one thing, it may well be a critical component of cleaning up certain industries, like cement, steel, and fertilizer production. It could also be easier, faster, or cheaper to retrofit some portion of the country’s fossil-fuel plants with these systems, rather than rebuild the entire electricity sector.

Finally, most climate studies show the world will need to remove a massive amount of carbon dioxide from the atmosphere to avoid extremely dangerous levels of warming, and natural systems like trees, plants, and soil can probably achieve only part of it. We may also need direct-air-capture machines, which would seem to be excluded under Sanders’s language concerning carbon capture or geoengineering.

Sanders says that climate change is “the single greatest challenge facing our country.” Voters who agree, however, will need to carefully consider whether his technically restrictive proposals are the best way to confront it.