Thursday, February 28, 2019

The New, Safer Nuclear Reactors that Might Help Stop Climate Change

From sodium-cooled fission to advanced fusion, a fresh generation of projects hopes to rekindle trust in nuclear energy.

 (Credit: A photograph taken in 2016 shows the central confinement vessel of a prototype fusion reactor built by Tri Alpha Energy (now TAE Technologies). Julian Berman) Click to Enlarge.
It might not be the first source you go to for environmental news, but its annual energy review is highly regarded by climate watchers.  And its 2018 message was stark: despite the angst over global warming, coal was responsible for 38% of the world’s power in 2017—precisely the same level as when the first global climate treaty was signed 20 years ago.  Worse still, greenhouse-gas emissions rose by 2.7% last year, the largest increase in seven years.

Such stagnation has led many policymakers and environmental groups to conclude that we need more nuclear energy.  Even United Nations researchers, not enthusiastic in the past, now say every plan to keep the planet’s temperature rise under 1.5 °C will rely on a substantial jump in nuclear energy.

But we’re headed in the other direction.  Germany is scheduled to shut down all its nuclear plants by 2022; Italy voted by referendum to block any future projects back in 2011.  And even if nuclear had broad public support (which it doesn’t), it’s expensive:  several nuclear plants in the US closed recently because they can’t compete with cheap shale gas.

“If the current situation continues, more nuclear power plants will likely close and be replaced primarily by natural gas, causing emissions to rise,” argued the Union of Concerned Scientists—historically nuclear skeptics—in 2018.  If all those plants shut down, estimates suggest, carbon emissions would increase by 6%.

At this point, the critical debate is not whether to support existing systems, says Edwin Lyman, acting director of the UCS’s nuclear safety project.  “A more practical question is whether it is realistic that new nuclear plants can be deployed over the next several decades at the pace needed.”
For many, though, the great energy hope remains nuclear fusion.  Fusion reactors mimic the nuclear process inside the sun, smashing lighter atoms together to turn them into heavier ones and releasing vast amounts of energy along the way.  In the sun that process is powered by gravity.  On Earth, engineers aim to replicate fusion conditions with unfathomably high temperatures—on the order of 150 million °C—but they have found it hard to confine the plasma required to fuse atoms.

One solution is being built by ITER, previously known as the International Thermonuclear Experimental Reactor, under construction since 2010 in Cadarache, France.  Its magnetic confinement system has global support, but costs have exploded to $22 billion amid delays and political wrangling.  The first experiments, originally scheduled for 2018, have been pushed back to 2025.

Vancouver’s General Fusion uses a combination of physical pressure and magnetic fields to create plasma pulses that last millionths of a second.  This is a less complicated approach than ITER’s, making it far cheaper—but technical challenges remain, including making titanium components that can handle the workload.  Still, General Fusion expects its reactors to be deployable in 10 to 15 years.

California-based TAE Technologies, meanwhile, has spent 20 years developing a fusion reactor that converts energy directly into electricity.  The company, which has received $500 million from investors, predicted in January that it would be commercial within five years.

Read more at The New, Safer Nuclear Reactors that Might Help Stop Climate Change

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