This is a really frustrating bit of recursive scientific illiteracy.
The issue was kicked off by a post which you can find at “friedcranes.org” though due to the cumbersome layout of this page by the time you read this you may have to search a bit. Look for the October 7th editorial on “Tonapah [sic], Nevada.”
The authors of the editorial are concerned about concentrating solar stations that incorporate thermal storage by using molten salts. The idea behind the technology is that solar power doesn’t work so well when the sun goes down, so if you use the sun to heat something that stays hot for a while after sunset, you can use that stored heat to turn a turbine and generate power. It’s a very common idea, and one often touted by people claiming that centralized solar is better than PV — though Solar Done Right’s Bill Powers has shown persuasively that solar thermal storage is a really frigging expensive way of generating electricity. It’s probably a technology worth developing further, in that there will likely be a few ways in which CSP proves to be useful, as in powering desalination plants, where you could use the concentrated brine as your source of molten salt, or something like that. But as a way of making electricity in the desert, it’s more a talking point than an economically feasible technology.
The molten salts generally used in this kind of tech are nitrates of potassium and sodium, commonly referred to as saltpeter and Chilean saltpeter, respectively. They’re cheap and abundant, and there are certain health hazards involved with their use: ingesting too much of either in preserved meats is thought to increase your risk of colon cancer, for one. They can be irritating to sensitive tissues. They have been known to start wars. If you heat it up to somewhere around 350°C and then accidentally spill it into the environment, it can cause nasty fires. In fact, these salts give off oxygen when heated, so they’re really good at starting fires under certain circumstances. Mix them finely with something quite flammable and apply a small spark, and they allow that flammable substance to burn far faster than it would without the saltpeter there, which is pretty much what those Ninth Century Chinese chemists found out when they discovered gunpowder, which is a mixture of potassium nitrate, powdered charcoal, and sulfur.
It’s a misunderstanding of that last property that the folks at friedcranes.org are worried about, as they say in their editorial:
We have been copying the Tonapah [sic], Nevada media with our editorials for months about the infamous Crescent Dunes Bomb being proposed to be built by SolarReserve in their soon-to-be-eradicated town in Nevada.
Are they interested? Nah!
Not one reporter has had the gumption to take five seconds to Google “sodium nitrate” and “potassium nitrate” and learn to their everlasting dismay that these chemicals are the highly explosive saltpeter and Chilean saltpeter, respectively—exactly the benign “molten salts” for energy storage that SolarReserve enthusiastically drones on and on about in their unending press releases.
Not one reporter in Tonapah [sic] has bothered to observe from SolarReserve’s own documents that 12 million gallons of these highly explosive chemicals will be stored in two tanks adjacent to 12,000 gallons of diesel fuel at the Tonapah [sic] site.
Not one reporter in Tonapah [sic] is the least bit dismayed that SolarReserve claims that they will keep these explosives at temperatures from 500°F to 1050°F despite the fact that both chemicals start boiling at about 750°F—presumably to begin venting “harmlessly” into Tonapah’s pristine air.
Not one reporter in Tonapah [sic] has had the guts to report that the 91,000 tons (compare that amount to just 2-½ tons of explosive and diesel fuel used by Timothy McVeigh to destroy the Alfred P. Murrah building in Oklahoma City) of high explosive SolarReserve® is so cavalierly planning to plop next to town has the equivalent explosive force of three atomic bombs the size of those we dropped on Japan at the end of the Second World War, albeit without the accompanying radiation.
Not one reporter in Tonapah [sic] has had the temerity to criticize the slip-shod engineering foisted off on the citizens of their Nevada town, nor to at least warn their friends and neighbors that an incendiary bullet fired into those massive tanks from a mile or two away (outside their purported secure perimeter fence patrolled by an alert security guard) would be sufficient to trigger the tragic explosions.
There’s a small problem with the Friedcranes folks’ argument: neither potassium nitrate nor sodium nitrate is explosive. In order to be explosive, something needs to be flammable, and both salts are in fact non-flammable. If you had a vat of boiling saltpeter and a lit match, and you tossed the lit match into the vat, the match would explode, as it burned furiously in the extra oxygen the saltpeter would likely be giving off. But the saltpeter wouldn’t explode, nor catch fire, nor do anything, really, that a similar quantity of molten metal wouldn’t do.
This is obviously a finer point for people, like the friedcranes folks, for whom chemistry is an arcane art. So let me put it this way:
- Burning, whether slowly as in a banked campfire or quickly as in a gigantic explosion, takes place when a substance combines with oxygen and gives off heat.
- A substance is non-flammable when there is no place in its molecules for oxygen to latch onto easily.
- Sometimes this is because you’re not providing a high enough concentration of oxygen or heat to make the combining happen rapidly: pure iron, for instance, is flammable in an atmosphere of pure oxygen, but at normal O2 concentrations and heat it combines with the oxygen far more slowly, rusting away over years.
- Sometimes, as in the case of water, a substance is non-flammable because it already contains as much oxygen as it can hold.
- Saltpeter has enough extra oxygen in it that it’s aching to give it away: heat it up a little and the oxygen comes streaming out.
Clearer? Saltpeter does not burn. Therefore it does not explode. It is safest kept away from highly flammable materials, and thus I do hope the TonOpah solar developers have their diesel tanks a discreet distance from their molten salt tanks. But if they don’t, what would happen in the worst possible accident is that the diesel would explode. It’s not pretty when big diesel tanks explode. People can get badly hurt and die. It happens. And if you have an exploded diesel tank, you’ve probably got flash temperatures high enough to vaporize some of the saltpeter, and thus you have a mild hazmat issue for first responders to deal with. In fact, Wikipedia’s page on potassium nitrate has this handy guide to firefighting around the stuff:
Fire Fighting Measures
Fire : Not combustible itself but substance is a strong oxidizer and its heat of reaction with reducing agents or combustibles may accelerate burning.
Explosion : No danger of explosion. KNO3 is an oxidising agent, so will accelerate combustion of combustibles.
Fire Extinguishing Media : Dry chemical, carbon dioxide, Halon, water spray, or fog. If water is used, apply from as far a distance as possible. Water spray may be used to keep fire exposed containers cool. Do not allow water runoff to enter sewers or waterways.
Special Information : Wear full protective clothing and breathing equipment for high-intensity fire or potential explosion conditions. This oxidizing material can increase the flammability of adjacent combustible materials.
So: no exploding saltpeter — despite the stuff having its own pesky cautions in dealing with it at high temperatures, none of which should be taken lightly — and thus no need for alarmist talk of 40-mile “blast zones” from accumulating even “millions of gallons” of it onsite, as the map taken under Fair Use provisions from the September 29 Friedcranes.org editorial would lead you to believe. That map is meant to express alarm over a larger solar thermal storage proposal in Colorado, significantly larger than the Tonopah Crescent Dunes project.
As for devastation in “Tonapah” from a saltpeter-enhanced explosion on the Crescent Dunes site, said site is just under 15 miles from town. It’s possible that some folks could badly injure themselves after being startled by the blast from 12,000 gallons of diesel fuel combining with oxygen in a fraction of a second: spilling hot coffee on themselves or falling off ladders or something. A north-facing window or two might even break. And workers at the plant itself will be in significant danger. But odds are the town will still be there afterward.
So a couple of enviros get their science badly wrong. It happens far more frequently than I am comfortable with — you can google “chemtrails” for jaw-dropping examples of same. The friedcranes folks seem to be nice enough people, though clearly just a bit too non-discerning in their choice of trusted sources of information. But people in the green camp getting their science utterly wrong is nothing new. One of the first things I had to do after taking over the Earth Island Journal for the first time was apologize to every single subscribing healthcare professional for the previous guy’s reference to “tuberculosis viruses” in milk. Not to mention the few hours I put in trying to explain to him how half-lives actually worked. A lot of this stuff has become background noise for me due to overexposure, and in most cases I’d have left the people at Friedcranes.org alone. They seem like perfectly nice people otherwise and life is short.
But then I read this piece in the Pahrump Valley Times.
SolarReserve refuted concerns circulated over the Internet by a Colorado environmental group that evoked fears of a catastrophe from an explosion from the molten salts used in a future solar power plant at Crescent Dunes.
Emails from FriedCranes.org state sodium nitrate and potassium nitrate are highly explosive saltpeter, not benign molten salts as SolarReserve touts in its company press releases.
After repeating FriedCranes’ statements about “highly explosive” nitrate salts of potassium and sodium, the article continues:
At the suggestion of the environmental group, an online check by the Pahrump Valley Times found sodium nitrate is used as an ingredient in fertilizer and pyrotechnics. Potassium nitrate is used as a fertilizer and a main component in stump removal; it’s also an oxidizing component in gunpowder.
SolarReserve had a ready answer to the group’s argument: The project is “fully permitted and completely safe.”
SolarReserve spokesman Andi Plocek said the questions over molten salt were put to rest in the environmental impact statement. She said other solar projects use molten salt storage, though most don’t have the solar tower that will be constructed at Crescent Dunes.
And this got me angry.
I’m not going to blame the reporter for this crappy story, because I don’t know what he actually turned in. Editors can take a perfectly good story and ruin it. But the Pahrump Valley Times should be ashamed of itself.
It is an objective fact that neither potassium nitrate nor sodium nitrate is explosive. A responsible article should have said so. Instead, the article turned objective fact into a he-said, she-said View from Nowhere piece, to borrow a phrase from media observer Jay Rosen.
I recognize that this isn’t the first example of scientific fact that’s been subject to this treatment. Anthropogenic global warming and evolution by natural selection are scientific facts, and they get covered this way all the time. Same goes for the spurious alleged link between vaccination and autism, and a lot of other such needless controversies.
But as far as I know, no one is seriously proposing we reexamine saltpeter’s flammability. One side of this story just has it unquestionably wrong, it’s a trivial matter to find out that they have it wrong, and that fact should have been in the first or second sentence of the piece. Which should have been framed differently anyway. “Local High School Student With B+ Average In Chemistry Refutes Fears of Saltpeter Explosion” might have been a good headline.