Earlier this month, Australian scientists at CSIRO (Commonwealth Science and Industrial Research Organization) announced a milestone for solar energy. For the first time, solar concentration technology has been used to create so-called supercritical steam. The term refers to the fact that water above a certain pressure (3208 PSI) no longer exists in a separate phase state from steam. Compress water that much, and the fluid becomes steam. This improves power plant efficiency — a modern fossil fuel power plant with supercritical boilers is typically 3.5% more efficient than a subcritical design. Supercritical designs also produce less air pollution, though that’s not applicable when discussing solar power.

This is a significant step forward for solar, which is still markedly more expensive and less efficient than competing alternatives. Most discussions of solar plant efficiency focus on solar panel technology, but energy is lost at every stage. CSIRO is crowing over the achievement and rightly so; it’s a real advance for solar power and its long-term future.

Supercritical solar

Courtesy of CSIRO

Max output and storage costs cripple long-term solar prospects

These new trends in solar, however, aren’t without their critics. Writing for The Energy Collective, Alex Trembath points out that despite recent innovations, solar power faces critical challenges without clear economic solutions. In this case, he’s discussing another milestone — the Crescent Dunes Solar Energy Project, which is poised to begin commercial operation. Crescent Dunes is the first commercial-scale molten salt solar plant in the United States. During the day, the plant transfers heat energy to the molten salt tanks, which is then released to provide power during the night and early dawn.

The problem is, even assuming this capability is exploited to its fullest, the capacity factor of the Crescent Dunes plant is just 52% (i.e. it is only operating at max capacity 52% of the time). The new nuclear reactors being built at Vogtle using an advanced Generation III design (Westinghouse’s AP1000) have a capacity factor of 90%. Combine those two facts, and Crescent Dunes costs nearly 2x what the Vogte Nuclear plants do.


Image from The Energy Collective

These sorts of cost comparisons aren’t popular with vast swathes of the environmental movement, who prefer to pretend that the Earth doesn’t actually rotate when solar efficiency is under discussion. Unfortunately, decades of scare tactics from the anti-nuclear crowd have poisoned the discussion around advanced nuclear technologies. Trotting out arguments from the 1960s about plant safety and fuel rod longevity makes for great ad copy, but it doesn’t do much to move the ball forward on actually cutting greenhouse gas emissions. Currently, the overwhelming majority of low-carbon energy is produced by two sources — hydro power and nuclear power.

Low carbon energy

The great irony of the environmental movement is that its constant yammering about the dangers of nuclear power have ignored the fact that coal mining on massive scales contributes more background radiation and kills far more people than nuclear power ever has. More than 70,000 coal miners have died of Black Lung disease since the 1970s, and the rate has increased in recent years thanks to a decade of cozy relationships between business and regulators. That 70,000 figure doesn’t count the number of people who were affected by higher pollutant levels — that’s strictly the number of miners who died from a disease directly related to the act of coal mining.

Deaths per TW of electricity generated

Deaths per TW of electricity generated

A 2012 study found that coal and oil caused far more deaths than any type of power generation, with nuclear power causing fewer deaths than any other type.

Despite flaws, a critical new approach to energy infrastructure

I’m unhappy about the scareism and rampant fear mongering that surround nuclear power in the US, but I’m also a realist. Using solar power to create supercritical steam or molten salt technologies are both critical advances because solar power has an inarguable role to play in future power generation. Separately from that, the research into molten salt storage matters because it addresses the enormous disparity between our ability to generate electricity and the ability to store and tap that generated capacity on demand.

From lithium-ion to flow batteries, the drive to ramp renewable production has also stimulated research into better methods of energy storage and containment. While that work is often linked to renewable energy, the two don’t have to be synonomous. Currently in the US, peak summer demand is met by bringing older, less-efficient power plants online to meet the surge. These plants tend to have the highest operator costs and dump higher amounts of pollutants into the atmosphere. Better battery technology could offset this by providing power during peak periods in lieu of bringing new plants online.

This kind of approach would invert the solar model; plants would recharge batteries at night, then draw them down during the day. As the EPA’s tougher carbon standards are adopted, it could provide an economical approach to cutting greenhouse gas levels and adopting green technology — without necessarily chaining that technology to solar power. It’s not that solar is a bad option, per se, but its intrinsically limited availability hurts widespread adoption — it’s only expected to account for a fraction of our power consumption by 2050, whereas wind is projected to gain far more market share. Nuclear, which is really our only chance at reducing our reliance on coal and oil in the short term, isn’t projected to hardly grow at all.