Instead of building giant concrete buildings filled with uranium, why not build smaller efficient buildings filled with people.

Nuclear power remains one of the most controversial and difficult issues for environmentalists. There are many reasons to want it to go away, from radiation to waste to danger from Fukushima-like disasters, but it has one over-arching virtue that seems more important all the time: it can produce vast amounts of power without carbon emissions from generation. That's why people like George Monbiot say "I don't understand why the nuclear question needs to divide the environment movement. Our underlying aim is the same: we all want to reduce human impacts on the biosphere."

Now Marc Gunther, who has been writing about environmental issues for years, puts his oar into these dangerous waters with a new article Nuclear power: A dilemma for climate change philanthropy. He's worried about the organizations that are anti-nuke, like the Sierra Club and Greenpeace and the philanthropists who support them. He quotes a book by Joshua S. Goldstein and Staffan A. Qvist, who argue that "the only way to rapidly decarbonize the world’s energy systems is with a rapid rollout of nuclear power and renewable energy."

Up until now, only one carbon-free energy source has proven able to scale up very quickly and — in the right conditions — affordably. That source is nuclear power.

Gunther notes that countries like Sweden and France, with big investments in nuclear power, have far lower emissions and the cheapest electricity in Europe. He also mentions the Province of Ontario, which has reduced CO2 emissions by 90 percent and eliminated coal.

This is why I believe that quote of the authors is misguided and wrong. I happen to live in that Province of Ontario, which has the most expensive electricity in Canada. (Although they are still less than what Americans pay in San Francisco, New York or even Detroit). Many here blame the last Liberal government for investing in renewables, but a big part of the problem is the huge "stranded debt" left over from building the nuclear plants in the first place, which we pay off with every bill.

Nuclear is expensive to build.

Nuclear power plants are hugely expensive to build and maintain; the Hinkley Point C plant in the UK is estimated to cost over 20 billion pounds. In Ontario, the Bruce Power plant is being refurbished right now with a cost of C$13 billion. Fixing Ontario's Darlington nuclear plants will cost C$12.8 billion. This is clean power, but it ain't what you would call affordable.

Nuclear is slow.

And then there is the question of scaling it up quickly. Reactors take a long time to build; the record is one in Argentina that took 33 years. According to Energy Matters that is an aberration.

At the other end of the scale, 18 reactors were completed in 3 years! 12 of those in Japan, 3 in the USA, 2 in Russia and 1 in Switzerland. These are a mixture of boiling water and pressurised water reactors. Clearly, it does not need to take forever to build new reactors given good supply chain, expertise and engineering protocols. The mean construction time of 441 reactors in use today was 7.5 years.

But that doesn't include the design and approval time, which might double it. Many blame the costs and time delays on regulation and over-design (who needs that big containment dome!) but good luck building a reactor today without one. There could be economies; Gunther quotes the author:

“Somebody’s got to innovate,” Goldstein says. “The goal is to make these less like building a complicated bridge and more like stamping Boeing jetliners as they come off an assembly line.”

Nuclear is complicated.

But it is more like a bridge than a plane. It is the same argument I use when people liken building prefab housing to building cars; planes can be the same everywhere in the world. A nuclear plant is going to need different foundations, different water supplies, has different neighbours and different earthquake zones. It is hard to make them all the same. Fundamentally, they are not, and the reactor is only a portion of the cost; the rest is just a big dumb building, with few economies of scale.

Nuclear power may be carbon free but building nuclear plants is carbon intensive.

Fukushima Dai-ichi nuclear plant under construction. Tomohiro Ohsumi / Getty Images

Then there is the embodied carbon of concrete and steel; a typical reactor might have 40,000 tons of steel and 200,000 tons of concrete. Production of that much concrete puts out about 180,000 tons of CO2, and making that much steel puts out 79,000 tons of CO2 which is a pretty big carbon burp for each power plant that these guys want to build.

Marc Gunther writes that "The Sierra Club, Greenpeace and 350.org built today’s climate movement, such as it is, and for that they deserve great credit. Yet they stand in the way of the only proven climate solution. “In a supreme irony,” Goldstein and Qvist write, “the very groups most actively opposing nuclear power are those most vocal about climate change.”

Nuclear is NOT the only proven climate solution.

Lawrence Livermore National Laboratory / Department of Energy

No, nuclear power is not the only proven climate solution. If you look at where the electricity is going, fully 75 percent is into buildings, with 25 percent into industry. If you look at where our biggest problems are, it is not with electricity generation; coal is down to 14 percent. Focus on where the power is going, not where it is coming from. The real and proven climate solution is to reduce demand, to fix those buildings, which would cost a whole lot less than replacing half the US electricity supply with nuclear power, and a whole lot less time.

We don't have time.

We continue to remind readers that the IPCC's line in the sand is that we have to cut carbon emissions by 45 percent by 2030 to limit temperature rise by 1.5°C. If we all agreed to build a fleet of new reactors starting tomorrow we wouldn't see the first of them online by 2030.

So instead of investing in giant concrete buildings filled with uranium that increase supply of electricity, why not instead invest in smaller, efficient wood buildings filled with people that reduce demand. And while we are busy building and fixing buildings, roll out more wind turbines and solar panels and especially, lots more batteries.

Living as I do in the Province of Ontario, I am thankful for the benefits of nuclear power that is carbon free. I am glad that they are continuing to fix the reactors that we have, even though it is expensive. This is probably good policy everywhere:

Fix the nukes we have instead of closing them, they are a sunk carbon cost. But we shouldn't be wasting time talking about new ones. We don't have it.