Bright idea: Make H when the Sun shines, and H when it doesn't

Researchers in Cologne, Germany, have successfully demonstrated a solar reactor known as CONTISOL, which promises to be able make hydrogen day and night while running on little more than air and sunlight. Hydrogen is often touted as a zero carbon fuel and promises a future free of potentially nasty emissions. However, the …

[JimmyPage]

Molten salt ?

aren't there some solar reactors which use the heat to melt salt, and that releases heat over the night so you get 24/7 power ?

[Graham Dawson]

Re: Molten salt ?

No. They hit a small problem of the salt solidifying in the pipework overnight. The salt also crystallises on the exchanger and acts as an insulator. They're a non-starter, sadly.

[I ain't Spartacus]

Re: Molten salt ?

Have they tried adding vinegar?

[Lee D]

Re: Molten salt ?

They tried, but then all the chips disappeared.

[a pressbutton]

Re: Molten salt ?

ah

The problem would be resolved if they sited the plant deep in the country and used the services of over weight mendicant monks.

i.e. deep fat friars.

[kryptonaut]

Re: Molten salt ?

But it would have to be positioned well out of reach of the chip monks.

[Anonymous Coward]

Re: Molten salt ?

What about pepper? Some peppers can be extremely hot.

[vir]

Re: Molten salt ?

The paper does mention molten copper as a suitable thermal storage medium. Let's see here...

1MW for 12 hours...4.3E10J

Copper's heat of fusion is 13.3kJ/mol...3.3E6mol...207t of copper...a cube 285cm on a side

Obviously that's an ideal case; they don't say what the round-trip efficiency might be. Also, that much copper costs about $1.5M, but the fact that it's molten would probably deter potential thieves.

[Pascal Monett]

Re: "probably deter potential thieves"

Nope. It's called a challenge.

[nijam]

Re: Molten salt ?

> ...probably deter potential thieves.

Based on the numpties who nick cable, they probably would notice until they spilt molten copper all over the place.

[Andy Tunnah]

Re: Molten salt ?

God damnit that is a quality pun @a pressbutton

[a pressbutton]

Re: Molten salt ?

thanks.

though on reflection, it could have been improved but late night posting with a large glass of benedictine always leads to something.

[Anonymous Coward]

Re: Molten salt ?

Can't find any verification of this salt problem at the GemaSolar station near Seville. Wikipedia states(!) that it has run at full capacity for almost 270 days since it was commissioned, and in 2013 ran continuously for 864 hours.

In fact it looks as though the GemaSolar designers were fully aware of potential issues and designed them out.

As for being a non-starter, sadly - as of 2012, somewhere near 30 new plants using Salt are reported to be 'in the pipeline'.

[Dodgy Geezer]

Re: Molten salt ?

...As for being a non-starter, sadly - as of 2012, somewhere near 30 new plants using Salt are reported to be 'in the pipeline'....

It's a complete failure thermodynamically, and hence a non-starter from that point of view.

But as a method of getting hold of taxpayer's money it's a very effective green scam, and all those 'new plants in the pipeline' are currently making a lot of green enterpreneurs very rich. From that point of view, it's money for nothing.....

Oh, and you should not be surprised that the Wiki only tells you the things that environmentalists want to hear...

[Dodgy Geezer]

Re: Molten salt ?

...As for being a non-starter, sadly - as of 2012, somewhere near 30 new plants using Salt are reported to be 'in the pipeline'....

It's a complete failure thermodynamically, and hence a non-starter from that point of view.

But as a method of getting hold of taxpayer's money it's a very effective green scam, and all those 'new plants in the pipeline' are currently making a lot of green enterpreneurs very rich. From that point of view, it's money for nothing.....

Oh, and you shoudl not be surprised that the Wiki only tells you things that environmentalists want to hear.....

[Anonymous Coward]

Re: Molten salt ?

I'm confused as to how it can be a complete failure when the GemaSolar plant has now been running for just over 6 years producing 110GWh a year (or 80GWh depending on where you read). 36 days continuously at full power. A complete failure thermodynamically would appear to be stretching it a bit.

Granted the EU grants etc probably have made the developers wealthy, but they are in it for the long term and the upfront costs of the plant were astronomic (it's not cheap energy by any means).

If anyone is intersted the plant is about 40 miles east of Seville Airport and the top of the tower is visible from about 40 miles away as a brilliant light just above the horizon, almost as bright as the sun itself. Driving past it at night after a typical August day and the top of the tower is still glowing red.

Air Nostrum flights from Jerez De La Frontera to Madrid pass it. Sit on the right-hand side.

[Alan Brown]

Re: Molten salt ?

"They hit a small problem of the salt solidifying in the pipework overnight. The salt also crystallises on the exchanger and acts as an insulator."

Interestingly, "solar salts" are being promoted as the working fluids for use in the tertiary loops of thorium reactors.

Of course if you have a thorium MSR you don't need the rest of the solar gubbins and faff, so is the simpler salt still a solar salt?

[Glad Im Done with IT]

carbon monoxide as byproduct???

Is the article missing something or what do they expect to do with this highly toxic gas?

[Frederic Bloggs]

Re: carbon monoxide as byproduct???

Burn it when the sun doesn't shine?

[Anonymous Coward]

Re: carbon monoxide as byproduct???

So you burn the carbon monoxide and hydrogen at night to get carbon dioxide and water.

So to sum it all up methane and water are "heated" to give carbon monoxide and hydrogen that can be stored and burnt later with oxygen from the air.

At this point I'm wondering about saving the methane till night and burning it then ..........

I "guess" as you have put solar energy in you must get more energy from burning the carbon monoxide and hydrogen (close to what we used to call town gas) than burning methane (a.k.a natural gas) but I'm not convinced as natural gas has about double the calorific value of town gas.

[Richard Boyce]

Re: carbon monoxide as byproduct???

I "guess" as you have put solar energy in you must get more energy from burning the carbon monoxide and hydrogen

I think the solar energy is effectively used to split water and the water is reformed at the end, releasing that extra energy. Doing that without the involvement of methane would be more difficult.

[Anonymous Coward]

Re: carbon monoxide as byproduct???

> At this point I'm wondering about saving the methane till night and burning it then ..........

Or rather more obviously: make methane-powered cars rater than hydrogen-powered ones.

Or turn it into methanol.

Clearly if you're using methane as a starting point, then you have carbon in the cycle - and CO2 is going to be released somewhere along the line.

[Cynic_999]

Re: carbon monoxide as byproduct???

"

Is the article missing something or what do they expect to do with this highly toxic gas?

"

Probably the same as all cars used to do - release it into the atmosphere. It is short-lived and at sea-level pressures soon oxidises into carbon dioxide.

[Lennart Sorensen]

Re: carbon monoxide as byproduct???

So yet more stuff released we are trying to make less of.

This sounds like a far from clean method for making clean energy.

So far I have no hope at all for hydrogen as a fuel source because there simply is no good way to make it, store it, or transport it.

[vir]

Re: carbon monoxide as byproduct???

The H2-CO mixture is syngas and can be used as is. The combustion products are water and carbon dioxide. It's not spectacular from an energy density standpoint, but if it's cheap...

[Dodgy Geezer]

Re: carbon monoxide as byproduct???

Which is an important food for plants. More is better...

[wobbly1]

Re: carbon monoxide as byproduct???

CO2 for plant growth CO for asphyxiation.

[Gordon 11]

Re: carbon monoxide as byproduct???

CO2 for plant growth CO for asphyxiation.

CO2 will asphyxiate - CO is poisonous (it binds to haemoglobin tighter than O2 does).

[Gordon 11]

Re: carbon monoxide as byproduct???

Probably the same as all cars used to do - release it into the atmosphere. It is short-lived and at sea-level pressures soon oxidises into carbon dioxide.

So the hydrogen may be a "zero-carbon fuel" but it's production produces a greenhouse gas, which is seemingly ignored?

Or is the assumption that it's OK because it's removing methane (which is worse)?

[mr.K]

Re: carbon monoxide as byproduct???

First of all, I would argue that carbon monoxide isn't a highly toxic gas, but the Wikipedia does indeed say that. I guess it comes down to what qualifies as "highly".

Second, carbon monoxide isn't the byproduct, but the product and it is used as an example. In their report it says that the use are for endothermic gas reactions that requires heat and a catalyst. As an example where you want to produce carbon monoxide and hydrogen gas from water and methane. That require heat and you end up burning some of the methane to keep the process going. However, if you use the sun as the heat source you can save some of the methane. In addition due to it being an endothermic reaction there is more energy in the end product than the gas you feed into it.

What you most certainly will not do is to dump it into the atmosphere. You have after all gone through great lengths to produce it. You either use it as a energy carrier i.e. fuel, or as a component in further chemical reactions.

In addition I see some commentards claiming the use it as heat during the night, but no. Their proposal is to use air as a thermal storage to tap into at night.

[John Smith 19]

Is the article missing something or what do they expect to do with this highly toxic gas?

Burning CO gives CO2.

It's a cyclic process.

The process is a closed cycle.

[JeffyPoooh]

Re: Is the article missing something or what do they expect to do with this highly toxic gas?

JS19 claimed "...burning CO...is a cyclic process..."

If the CO originates from 'fossil fuel' methane (it would), and the end result CO2 is dumped in the atmosphere (likely), then the only cycle would be the too-slow 'fossil fuel closed loop' lasting hundreds of millions of years.

[DCFusor]

Hydrogen is a terrible

way to store energy anyway, despite initial high hopes. It's super dangerous (I work in a lab that uses it), explodes in any mixture with air, embrittles metals, is hard to store any quantity of in a small space as would be needed for cars.. and when burned, say in an IC engine, is no better than gasoline re thermodynamic efficiency. Fuel cells need catalysts that are in far too short supply to make enough cars to serve a single US state.

Truth hurts, but there it is. Batteries long ago became better than hydrogen systems, and are a lot safer.

Nature's way of storing hydrogen is hydrocarbons. Works really well, we use them because of that - too bad they also have carbon that's going to burn too and make pollution...but nothing else works for storing energy quite so well.

I'm a scientist and I eat my own dogfood, living off the grid since long before it was cost effective (solar was $6 a watt when I started). Hydrogen like my lab uses in fusion research, is pretty nasty stuff if you get a leak, and it's about the second leakiest substance on earth after helium. The tiniest leak in a hose gives you instant flame even in a non sparking environment room. If you're lucky, it's right away, and not an explosion after a little more leaks and mixes with air.

Guns are a lot safer, at least you have to pull a trigger.

[Charlie Clark]

Re: Hydrogen is a terrible

I was surprised with the CH₄ reduction idea anyway. I thought the best candidate was CO₂ + H₂O to CH₄ which requires less power and is easy to store. You can then go from this to H₂ via methanol in a fuel cell if you want but basically LPG is good enough.

There are two problems with this: it requires energy input which makes it uneconomic at the moment unless you take duty into consideration but doing this would make it an ideal candidate for fraud. Mind you, electric vehicles are currently already heavily subsidised when compare with petrol due to the lack of duty.

But I'm not a scientist and haven't looked at this in detail for many years, so please do correct me!

[Anonymous Coward]

Re: Hydrogen is a terrible

Your logic is absolutely right, but you need a source of fairly concentrated (possibly purified) CO2 so the atmosphere isn't really a suitable source. You could concentrate the atmospheric CO2, but when you factor in all the energy use and losses that's just bloody mad. If instead you're taking (say) a power station exhaust stack as your CO2 source, it doesn't look terribly renewable (even if it has merit).

I have been moving in the field of energy policy for some years, and I can summarise the current EU and government policy direction as "Do renewable stuff. Don't ask us how, we don't have a fucking clue."

[Anonymous Coward]

Re: policy direction "Do renewable stuff. Don't ask us how, we don't have a fucking clue."

This seems quite sensible - very few politicians would be qualified to design power plants. Do we really want them having input on what colour the pipes should be? :-)

[Dodgy Geezer]

Re: policy direction "Do renewable stuff. Don't ask us how, we don't have a fucking clue."

Doesn't seem sensible to me. It's my money the ignorant politicicians are shovelling into continuously failing projects - like CCS, wave power....

[David Nash]

Re: policy direction "Do renewable stuff. Don't ask us how, we don't have a fucking clue."

"This seems quite sensible...very few politicians would be qualified"

True, but also very few politicians would be qualified in the area of data encryption yet they still feel they can have a policy of "make a magic backdoor that only we can use...don't ask us how"

[nijam]

Re: Hydrogen is a terrible

> I can summarise the current EU and government policy direction as "Do renewable stuff. Don't ask us how, we don't have a fucking clue."

I suspect that's not quite correct; surely the policy is more likely to be "Do renewable stuff. Don't care if it's possible, just do it."

[Charlie Clark]

Re: Hydrogen is a terrible

you need a source of fairly concentrated (possibly purified) CO2

Should be possible to get this from industrial processes or even in a closed-loop situation with methane acting as the store. This can only ever make sense if you have consistently but not persistently have more energy coming in than you have demand for: the apocryphal windy, desert stations for example.

"Do renewable stuff. Don't ask us how, we don't have a fucking clue."

Possibly, but then that's how some of the best research gets started. If you look at how much money has been spunked on the various white elephants (how the fuck are we ever going to safely decommission all those nuclear power stations?) I don't mind a small amount getting thrown at this. But I do agree we need to start rolling the back the subsidies.

[Alan Brown]

Re: Hydrogen is a terrible

"how the fuck are we ever going to safely decommission all those nuclear power stations?"

More easily than all those coal ash ponds across the USA (the 2 largest environmental disasters in the USA so far this century have been coal ash pond dam breaks).

Highly radioactive stuff is easy to deal with - "Wait a while". Three Mile Island's melted-down reactor is being diassembled at the moment. Chemical poisons are the gift that keeps on giving.

The better question to ask is why we're still using nuclear power systems that involve radioactive material being plonked in the middle of a steam boiler (bomb) instead of using a safer heat transfer medium/moderator proven in the 1960s by the same guy who invented the steam boiler method for a submarine and realised that scaling it up to power station sizes was too dangerous to contemplate.

[JCitizen]

Re: Hydrogen is a terrible

That is why they call them "fool" cells.

[Anonymous Coward]

Re: Hydrogen is a terrible

These links below are just for the last month. I'm well aware of the embrittlement problem as we have to deal with the same problem, plus neutron embrittlement, in (Navy) nuclear reactors. Rather a lot of people playing in this end of materials science.

https://phys.org/news/2018-02-uncovers-mechanism-water-splitting-catalyst.html

https://phys.org/news/2018-01-potential-metal-nanoparticles-catalysts-fast.html

https://phys.org/news/2018-02-high-efficiency-low-cost-catalyst-electrolysis.html

https://phys.org/news/2018-02-infrared-lasers-reveal-unprecedented-surface.html

[Dodgy Geezer]

Re: Hydrogen is a terrible

...too bad they also have carbon that's going to burn too and make pollution......

What pollution? If you burn it right you only get CO2 - which everyone knows is a trace gas critical to plant life, and one we could do with lot greater concentration in the atmosphere. Pity humans can't really add very much compared to natural sources.

Anyone who thinks that CO2 causes global warming should look at the model predictions for this, then examine the actual observed temperatures. Satellite - not artificially-adjusted ground data...

[strum]

Re: Hydrogen is a terrible

>Anyone who thinks that CO2 causes global warming

...is someone who actually knows what they're talking about - not some diogy geezer on the internet.

It's extraordinary how desperate some people are that renewables can't possibly (be allowed to) work.

[annodomini2]

Re: Hydrogen is a terrible

In addition: all that energy wasted compressing and cooling (due to compression) to put it into a form compact enough to put it in a car.

[Bucky 2]

Arid Landscapes

The problem with arid landscapes is that they frequently have fragile ecosystems filled with at-risk species. They're not the barren wastelands that they seem to be at first glance, just waiting for the miracle of industrialization to make use of them.

This doesn't mean they're unavailable for solar farming altogether. But ignoring the issue is foolish at best.

[Cuddles]

Re: Arid Landscapes

"They're not the barren wastelands that they seem to be at first glance"

They will be once we're done with them.

[John Smith 19]

First propused by the ORL in the early 80's under the "SolChem" initiative.

The key difference between solar thermal and solar electric systems is that solar electric (PV) systems operate at or just above the band gap energy. Below that energy photons just heat the PV cell material. Above it just seems to result in higher kinetic electrons.

OTOH solar thermal can use all of the solar spectrum to drive the process, and the reaction products can either be stored or moved on and used elsewhere.

[Schultz]

"... when the Sun shines, and when it doesn't"

So in some 5 billion years, when the sun stops shining, this technology will really shine!

Oh, you mean _where_ the sun doesn't shine? Must have misread that part.

[Anonymous Coward]

Keep trying we'll find something in a while.

Salts in Molten Salt Solar thermal, especially sodium fluoride are nearly as dangerous sodium cyanide if they escape into the environment.

A gas company in Australia for domestic supply strips the hydrogen off natural gas and releases the carbon, uses hydrogen to create hot water and drive a piston creating electricity, Customer gets hot water, as part of the process and cheaper electricity.

But Hydrogen storage is not really an energy source, must be considered as a battery only.

didn't know it embrittles metals as {Hydrogen is a terrible - DCFusor } says.

I always thought Hydrogen would be great storage.

I like to test something as if it is Carbon Neutral and Fossil Fuel Negative.

Carbon Neutral doesn't create more than it absorbs and Fossil Fuel Negative, doesn't use more from the ground.

Got to consider the carbon cost of tooling up, plant build right thru to household or industrial adaption to usage methods and failings, there are plenty of hidden costs in there not often mentioned.

It is as a chain of ideas, that we must move along the chain a fair way before another really good idea emerges. Innovation is the providing a solution for an existing problem. Destructive/Distractive innovation only pushes a invention without a problem to solve or something less good for the market than what already exists.

Keep trying we'll find something in a while.

[Anonymous Coward]

Re: Keep trying we'll find something in a while.

> always thought Hydrogen would be great storage.

??? Probably you never tried storing it then.

Buy a helium balloon and see how many days it stays inflated (despite the foil coating). A tank of pure H₂ in your car would probably disperse within a fortnight.

[Charles 9]

Re: Keep trying we'll find something in a while.

The thing is, hydrogen and helium gases are the two tiniest things in the universe (H2 has a molecular weight of just 2, He has an atomic weight of 4 and has the advantage, being a noble gas, of being inert and existing naturally in atomic form). Basically, they have the ability to slip through nanoscopic gaps in otherwise-solid materials. That's why helium always escapes balloons (seen under a powerful microscope, balloon rubber and even mylar have these nanoscopic holes in their materials--most gases wouldn't fit but helium can). That was one of the roadblocks of putting helium into hard drives: developing a material that was really, REALLY gastight, even re: helium.

[Alan Brown]

Re: Keep trying we'll find something in a while.

"Buy a helium balloon and see how many days it stays inflated (despite the foil coating)."

Or do the same with a balloon full of hydrogen and observe what what happens to the rubber.

[John Smith 19]

"Salts in Molten Salt Solar thermal, especially sodium fluoride are nearly as dangerous"

Which is why SolChem (which was designed to use low cost readily available materials, because it was expected to deploy on a huge scale) used Sodium Chloride.

That's the stuff you sprinkle on your food.

It's true molten salt system must be kept water free, which means a "bake out" in commissioning, then running sealed (in fact in SolChem they planned to sub divide the mass into welded shut re-purposed aerosol cans)

[Dodgy Geezer]

Re: "Salts in Molten Salt Solar thermal, especially sodium fluoride are nearly as dangerous"

..."Salts in Molten Salt Solar thermal, especially sodium fluoride are nearly as dangerous"

Which is why SolChem (which was designed to use low cost readily available materials, because it was expected to deploy on a huge scale) used Sodium Chloride.

That's the stuff you sprinkle on your food....

Er... I think that the point the OP was trying to make was that MOLTEN corrosive materials are highly dangerous. And they are.

Chemically it may be what I put on my food, but even when I add salt to curry it doesn't get THAT hot....

[Alan Brown]

Re: "Salts in Molten Salt Solar thermal, especially sodium fluoride are nearly as dangerous"

"MOLTEN corrosive materials are highly dangerous. "

Molten salt isn't particularly corrosive. It's only when mixed with water that it becomes ionic and corrosive and that's not happening at 400C

[JeffyPoooh]

Making hydrogen at night merely saves a tank

Instead of setting aside roughly half the solar energy to be used later, they could just run the reactor roughly twice as hard during the day, and store the roughly doubled output of hydrogen in a tank.

In other words, they've replaced a big tank of stored hydrogen gas (or perhaps syngas) with a big tank of stored heat. What's easier to store for later? Gas or heat?

If there's some advantage to keeping the reactor continuously hot and running 24/7, or the size & peak output of the 24/7 reactor is thus smaller, then stored solar heat may be a very good thing.

But storing vast amounts of high temperature heat energy is non-trivial. Such a technology would have many more planet saving applications than this weird little niche.

[Anonymous Coward]

Re: Making hydrogen at night merely saves a tank

> Instead of setting aside roughly half the solar energy to be used later, they could just run the reactor roughly twice as hard during the day, and store the roughly doubled output of hydrogen in a tank.

> In other words, they've replaced a big tank of stored hydrogen gas (or perhaps syngas) with a big tank of stored heat. What's easier to store for later? Gas or heat?

It's an Economy 7 storage heater farm!

[Alan Brown]

Re: Making hydrogen at night merely saves a tank

"What's easier to store for later? Gas or heat?"

That depends what you're doing, but one of the bigger problems with solar thermal plants is that they've generally turned out to be prodigious consumers of natural gas to keep them warm/hot overnight, else they have a large startup lag in the morning.

The Nevada plant apparently uses 2/3 of the amount of gas that a purely gas-driven power station would consume, with a much higher capital and maintenance cost.

I don't know how the Spanish plant is managing to stay hot enough to keep its salts molten all night but the bigger problem is that even if it works as claimed, such plants simply can't scale to provide existing power demands, let alone replace carbon emissions in transportation and domestic heating, because the amount of suitable land isn't there (the Spanish plant consumes a lot of cooling water, which is ok due to its location. Most solar plants don't have readily available water sources)

[Missing Semicolon]

Boyle's Law

If you compress Hydrogen for storage, then release it slowly into your engine to use it, where does the energy that went into compressing the Hydrogen go?

[Francis Boyle]

Charles' law

Most of it is lost as heat at the point of compression.

[Charles 9]

Re: Charles' law

That's why a coolant compressor is always outside the housing; it needs someplace to vent.

It's also why releasing this stored gas causes a cooling effect (the key to most artificial refrigeration). When the gases expand, they absorb heat to return to their original state.

[rhydy]

Re: Boyle's Law

Genuinely good question, simple answer: the heat from compression results in hot compression apparatus, hot tank and hot tank contents. Then all that heat is dissipated ambiently and lost quite quickly (insulating the tank to keep them warm merely slows that loss). The reverse happens when you release the gas, it comes out very cold as it expands.

[Alan Brown]

Re: Boyle's Law

"where does the energy that went into compressing the Hydrogen go?"

That depends if you kept the heat or not.

You're right to point this out though, this is the fallacious part about most compressed-air storage systems. They dump the heat overboard and rely on being able to reabsorb it from the atmosphere later, except they never can recapture as much in a short period as was lost in that short period.

Some quick math on the "underground storage cavern" suggestions for compressed air storage driven by windmills show that they'd get hot enough to melt rocks (and the pipework).

[rhydy]

Methane is a fossil fuel. So if this about avoiding oil imports rather than combatting climate change then better to simply run your engine on Hydrogen like BMW did over a decade ago, than "green washing" natural gas (the other name for methane).

[ArrZarr]

Methane extracted from the ground is a fossil fuel.

Methane created artificially without the use of anything extracted from the ground is renewable.

[Alan Brown]

"Methane created artificially without the use of anything extracted from the ground is renewable."

Yes, but, how do you create it?

If you're going to use a Haber process to create hydrogen and then tack on carbon from the atmosphere to give yourself a stable gas, then why strip it again later?

And for the most part, if you're going to tack on atmospheric carbon to make a transportable fuel, why spend all that effort trying to temporarily sequester trace amounts of carbon only to burn it again, when nitrogen is a lot more readily available and ammonia is just as usable as a fuel?

The whole thing smells of greenwash.