How Clean is Hydrogen, Actually?
February 8, 2023 12:44 AM   Subscribe

How clean is hydrogen really - worse than methane? Robert Llewelyn from Fully Charged on a podcast with David Cebon from the Hydrogen Science Coalition about the "colours of hydrogen", the lobbying process in play at the moment and the relationship with the underlying science. Its an in-depth, but informative discussion, I found.
posted by rongorongo (58 comments total) 9 users marked this as a favorite
 
A must see interview if you have any interest in the future of energy production. It's not an outright dismissal of the technology, but a level headed outline of why it's just not feasible to produce emissions-free hydrogen on a vast scale.
posted by benoliver999 at 2:08 AM on February 8, 2023


Is there a summary? The video runs an hour and five minutes.
posted by gimonca at 3:18 AM on February 8, 2023 [4 favorites]


I like that Robert Llewelyn has been involved with fossil fuel alternatives for long enough to have driven every commercially available hydrogen fuel cell car and remembered the decade old promises of the imminent roll-out of carbon capture/storage technology that remain unfulfilled. There is a lot about hydrogen as a fuel which sounds compelling at first (You only get water vapour from your car exhaust - no pollutants - wow! We can just switch over our gas boilers to use hydrogen - how convenient!) but which doesn't bear scrutiny at all. In general - cases for hydrogen as a fuel seem limited to me. On the other hand, the case for using green hydrogen, rather than grey, to make fertiliser should be an urgent switch.

This page from the University of Delft - also called "How clean is hydrogen really" is quite a nice summary of the issues from if you wanted to read them that way. TLDR: The CO2 emissions for hydrogen production lie mid way between diesel and coal at present. Greener production methods exist - but they tend to require significantly more energy than just using the electricity directly. Hydrogen is also a massive pain to store or pipe.
posted by rongorongo at 3:22 AM on February 8, 2023 [7 favorites]


@gimonica, not an official summary but the main points seem to be
hydrogen doesn't have a lot of uses as a fuel and appears to be more about green washing natural gas. sell people the idea of green hydrogen and then instead sell people blue hydrogen, hydrogen created by using natural gas and co2 storage, which is bad emission wise because natural gas leaks

green hydrogen has a place, which is using it as a chemical, for fertilisers and stainless steel and should be generated at the point of use

hydrogen doesn't really have a place used as a land transport fuel, using electrolysis is 75% efficient, so 1 electricity gets you .75 hydrogen, and then using it as a vehicle fuel, you lose another 50%, so it's only 37% efficient before taking into consideration things like transporting the hydrogen to its point of use

it's really difficult to store/move, instead of one fuel truck tanker to supply your petrol for the day, you'd need 18 hydrogen trucks tankers instead, and if you just created hydrogen at the service station you'd need 3x the electricity for each hydrogen car vs electric car

speaking logistically for trucking in the UK, electric trucks will be fine, there's enough time in existing legislated work breaks to charge a truck, so charge vehicles where you can

hydrogen doesn't have a place for heating, using an electric heat pump is more efficient as it doesn't create heat, it moves it, so 1 electricity = 3 heat, where as the hydrogen path leads to 0.5 heat, so an electric heat pump is 6x better

shipping/air transport weren't particularly discussed except at the end to say its a difficult problem and maybe biofuels or just using fossil fuels might be better

thanks for sharing @rongorongo
posted by pav lova's pavlovian palaver at 4:42 AM on February 8, 2023 [12 favorites]


Is there a summary? The video runs an hour and five minutes.

I read the transcript and there doesn't seem to be anything new or interesting there. He raises a bunch of problems which have been discussed and debated for the past 20 years at least.

It costs a lot of electricity! Yes, but he didn't seem to acknowledge many parts of the world have or will soon have negative electricity pricing due to increasing use of solar and wind, this would be a decent way to basically "store" excess energy, rather than building expensive lithium ion batteries. Also he says it's inefficient, well, relative to what, gasoline is inefficient too. And efficiency doesn't matter when electricity prices are negative and that energy would be wasted anyway.

It's hard to transport hydrogen because of its small molecular mass! Well, yes, which is why some projects being worked on now are creating hydrogen then fusing it with carbon dioxide from the air to make methane or propane which can be channeled through existing infrastructure.

I worked with a team on Liquid Phase Injection engines. The car takes LPG and instead of a traditional carburetor which mixes vaporized propane with air then feeds it into the engine, you have an injection system that pumps liquid propane direct into the engine, a similar leap in technology to where gasoline engines suddenly gained huge efficiency and power increases going to direct injection.

LPI cars were amazing, significantly more powerful than their gasoline equivalent. Their power output was off the charts due to the supercooling effect as LPG boiled to gas in the engine, effectively increasing the fuel air density like a turbocharger and increasing the temperature gradient between the input / output of the engine. The initial prototypes snapped the driveshafts and we had to downrate the engine output to keep it manageable.

It burns extremely clean as well - you burn LPG indoors, inches away from your food, every single day. You'd never ever do that with gasoline or diesel.

And from a safety point of view, the LPG pressure vessel in your car is probably the strongest part of the car, you'll never rupture it. Fuel tanks are usually plastic with no structural strength (if you place one on the floor, it collapses, it only holds its shape because it's secured to the car's internal structure). Also if you have an accident? Instead of flammable liquid pooling around your car, if the regulator valve somehow breaks and the failsafe doesn't shut it off, it just vents into the atmosphere and escapes upwards.

I even liked the fueling system, with a screw on fuel filler that makes it impossible to spill any on your car or yourself.

Ultimately the technology became a dead end because of the price of natural gas. There was increasing demand from Europe as they switched to gas for power generation because it was cleaner than coal, and the big turning point was Fukushima, where all the nuclear power plants in Japan were shut down and generation switched over to gas, dramatically increasing demand. Prices have never been the same since.

Anyway, I have a pipe dream of carbon neutral LPG supply (maybe a methane dominant variant?) created from a factory that gets paid to suck up electricity during periods of negative pricing due to solar / wind overproduction, powering a fleet of cars that burn as clean as your gas stove in your home.

There's definitely still a place for EVs, but I think hydrogen fuel generation can coexist beside it as a way of soaking up excess power generation.

(not that your gas stove at home is entirely harmless, as we are finding out, but it's at least 10x better than the current fleet of diesel and gasoline cars on the road).
posted by xdvesper at 4:44 AM on February 8, 2023 [11 favorites]


... parking my LPI car in the garage and getting out and "not" smelling the whiff of petrol or diesel fumes was a revelation, similar to if one purchased an EV. And so was flooring the accelerator on it. And at the time it cost half as much to run as a regular petrol or diesel car because gas was cheap.

For a few glorious years it felt like a hint of the future, a bit of a taste of what EVs promised - cheaper cost to run, cleaner emissions, more power and acceleration.
posted by xdvesper at 4:55 AM on February 8, 2023


you burn LPG indoors, inches away from your food, every single day. You'd never ever do that with gasoline or diesel.

No I don't, with rare exceptions when there's no mains gas. There's a big difference between methane and propane.

There's no evidence that hydrogen generation capacity is cheaper per MW than battery storage, even ignoring the inefficiency of electrolysis and the conversion.

Where hydrogen has a future is in the many industrial processes where a reducing agent is needed, most notably fertiliser and steel production. For transport, yep, maybe for ships and airliners.
posted by ambrosen at 4:58 AM on February 8, 2023 [1 favorite]


You'd never ever do that with gasoline or diesel.

I’ve eaten many a meal cooked with Coleman fuel over the years, especially camping with my family as a child. But other than that minor quibble, that’s a great comment.
posted by TedW at 5:21 AM on February 8, 2023


I do burn propane for cooking, because I live in a place with no gas utility and a shitty electrical grid, and even with solar and battery backup, I know from experience that enough battery to last through many days of outage along with overcast weather would be prohibitive, plus the risk of damage to solar panels due to high winds.

A tank of propane seems like the only reasonable way to ensure I can cook food in the event of a natural disaster. I imagine this is true throughout much of the developing world, and it's be great if it could be produced more cleanly for uses where it makes sense.

(Not that solving the political problems necessary to improve the grid wouldn’t be more ideal.)
posted by mubba at 5:25 AM on February 8, 2023


Fair criticism, I used LPG propane and gas mains methane interchangeably there in the comment, I'm of the impression that their emissions profile is similar enough, in the context of being compared with petrol and diesel.

I grew up in a country with no gas mains, every kitchen had two LPG tanks in the back which we swapped out when one was empty, then when the "gas man" came around with his truck once a month or something, we'd swap an empty bottle for a new one and pay him some money. Now I live somewhere with gas mains but I've swapped to an all electric future.

I tend to agree we have no idea if hydrogen is even cheaper than batteries, but just trying to paint a somewhat more realistic picture of how it could work by reusing existing technology and infrastructure, which seems a surer bet than entirely reinventing everything. In any case it's a pressure relief valve of sorts, if we go full into battery building mode and dry up all the available sources of lithium and the battery prices shoot up, hydrogen generation exists as an alternative at some $ value of battery price parity.
posted by xdvesper at 5:43 AM on February 8, 2023 [1 favorite]




hydrogen doesn't really have a place used as a land transport fuel

I'd certainly agree w/r/t cars, but it seems like trains could make use of it. You don't have the same problems developing a huge infrastructure, and caring extra fuel is not as big a problem.
posted by CheeseDigestsAll at 5:58 AM on February 8, 2023


I wonder how much money the Hydrogen Science Coalition gets from Toyota, whose leadership has basically bet the company on vehicles that continue to burn fossil fuels in one form or another (including in the form of hydrogen).

It's just funny to see an advocacy group use phrases like "evidence-based", which mimics similar language Exxon used in NYTimes editorials to promote the continued extraction and use of oil, in spite of its own research into human-caused climate change.

For Many, Hydrogen Is the Fuel of the Future. New Research Raises Doubts.
Industry has been promoting hydrogen as a reliable, next-generation fuel to power cars, heat homes and generate electricity. It may, in fact, be worse for the climate than previously thought.

It’s hailed as the clean energy of the future. But hydrogen produces ‘substantial’ emissions, study shows.
New research casts doubt on the environmental credentials of ‘blue’ hydrogen produced using fossil fuels
posted by They sucked his brains out! at 6:09 AM on February 8, 2023 [4 favorites]


Also if you have an accident? Instead of flammable liquid pooling around your car, if the regulator valve somehow breaks and the failsafe doesn't shut it off, [LPG] just vents into the atmosphere and escapes upwards.

It’s not easy to rupture an LPG pressure vessel, but when a leak does happen LPG is heavier than air. It does not just escape upwards. It runs along the ground, settles and pools in low spots, and combusts or explodes when ignited.
posted by Songdog at 6:26 AM on February 8, 2023 [2 favorites]


Industry has been promoting hydrogen as a reliable, next-generation fuel to power cars, heat homes

The evidence concerning the use of hydrogen for home heating is almost entirely negative. Jan Rosenow found 32 articles for his literature review in Joule, published in Oct,2022. You should be able to access it via researchgate.

None of the 32 suggested there was an economically viable route to using hydrogen for home heating. There have been 4 subsequently published papers on the sam topic highlighted on twitter. Three of them back the central point that hydrogen is very unlikely to be able to viably heat homes. The other said it would be great to use hydrogen for home heating, but turned out to have been supported by a gas company.

Earlier this month, Weidner et al published "Planetary boundaries assessment of deep decarbonisation options for building heating in the European Union" in Energy Conversion & Management. The headline shows "A strong trade-off for hydrogen was identified, with blue hydrogen being cost-competitive but vastly unsustainable (when applied to heating) and green hydrogen being 2–3 times more expensive than electrification". Not Open Access unfortunately and not available on Researchgate as yet.
posted by biffa at 6:34 AM on February 8, 2023 [5 favorites]


Much of the discussion of hydrogen is scammy because it relies on "Blue" hydrogen. Blue Hydrogen, created by reforming hydrocarbons, relies on so-called carbon capture to be not gray/black hydrogen. And carbon capture is still a massive scam. Not just a financial one, but a thermodynamic one. And you can't get away with thermodynamic scams.
posted by bonehead at 6:36 AM on February 8, 2023 [7 favorites]


I had thought that hydrogen alone was a difficult fuel, but that there was some promise in synthesizing hydrogen derivatives (e.g., octane, hexane, various -anes and -enes). Is that not a thing?
posted by argybarg at 6:59 AM on February 8, 2023 [1 favorite]


when a leak does happen LPG is heavier than air. It does not just escape upwards. It runs along the ground, settles and pools in low spots, and combusts or explodes when ignited.

This is also true. As much as I put up with it, the risk is very real. Just yesterday a man near me was seriously burned, and gas explosions have killed people and destroyed houses multiple times in recent years.
posted by mubba at 7:00 AM on February 8, 2023


Using current tech, a 100 kg hydrogen tank holds about 5 kg of hydrogen. This is 33.6*5 = 168 kWh of energy.

Lithium ion is a bit above 260 wh/kg, so 26 kWh of energy per 100 kg of battery.

The hydrogen storage is 6.5x more efficient, watts-per-kg, than the LiIon energy storage.

As the biggest obstacle to elecrified transport is the battery cost and weight, not the fuel costs, this is a pretty big hydrogen advantage.

Converting water into H2 and O2 may be lossy, but faster fueling and less weight and cost dedicated to on-vehicle storage is a pretty powerful argument for H2. The energy costs for electric cars are extremely low -- making the energy costs 4x larger in exchange for lower capital costs and longer ranges seems like a great bargain.

The problem is that we don't *have* good commercial H2 cars while electrical cars are getting iteratively better. On the other hand, electrical transport trucks look economically suicidal due to battery weight problems; H2 transport trucks with 3x lighter energy storage (even assuming 50% loss compared to a battery) would make the math much better.

I've seen the numbers on battery-based 18 wheelers, and it doesn't work (as a replacement tech) without a massive technological improvement. But if you drop the weight of the batteries by 3x, suddenly the math says this is a viable replacement.
posted by NotAYakk at 7:03 AM on February 8, 2023 [1 favorite]


I can give you numbers on 44 ton trucks with batteries and safe working hours regulations. If you can drive at 90km/h for up to 4 hours 30 minutes before taking a 45 minute break, then you will need a range of 400 kilometres, which you can get from an 800kWh battery, say 1000kWh for margin for hills. You'll need to be able to recharge at about 1.2MW to get fully charged in the rest break, so truck stops will need pretty high capacity electricity supplies, but thankfully most of those are adjacent to major routes where it makes sense to run grid upgrades. Obviously you'll want the whole of this regulatory area to be on a highly integrated grid to make it easier to upgrade the grid connections.

This doesn't seem to be especially hard. I'll leave it as an exercise for the reader to determine what percentage of global road freight ton kilometres are already transported under these constraints. I'm confident it'll be one of the top 2 regulatory areas for road freight globally.
posted by ambrosen at 7:19 AM on February 8, 2023 [1 favorite]


I did not listen to TFV. I just scanned the thread.

The hydrogen proponents need to go away until they can come up with a good-faith answer to the objections about hydrogen embrittlement (and other problems deriving from the underlying cause, namely the tinyness of H2 molecules compared to the particles of literally any other substance that humans have to work with) and its implications for storage and transport.
posted by Aardvark Cheeselog at 7:31 AM on February 8, 2023


And carbon capture is still a massive scam. Not just a financial one, but a thermodynamic one. And you can't get away with thermodynamic scams.

I pretty much agree with you - but also refer you to Jo Scott’s The Global Thermostat - A Crazy Megaproject That Just Might Work . I think, in the end, his argument is that Carbon Capture is only going to help if it was done using the most cost efficient of a range of proposed techniques, if it were done using energy from geothermal sources, if we are OK about the risk of damage of storing the stored carbon dioxide on the sea bed and if we pump at least as much money into the exercise as we, as a global society ,have been into subsidising petrochemicals - and continue to do so over several decades. Also, on no account should the oil industry be let anywhere near the management of the exercise.
posted by rongorongo at 7:38 AM on February 8, 2023


You forgot about the environmental racism.

Most hydrogen proposals are in cancer alley and I-10, in African American areas without voting rights.

Also, most hydrogen proposals are also ammonia proposals--using methane to make hydrogen to make ammonia, be uase there s no infrastructure to Market hydrogen, the market is in ammonia.

The kids in Donaldsonville have asthma and Leukemia from the existing ammonia plants. If people get caught in the rain in cancer alley, the ammonia can eat the skin from their faces, according to Eve Miller, speaking to the Tulane environmental law clinic.

Same oil industry bullshit, new bottles.

If you look at the Louisiana BIF proposal, Louisiana pretty much admits there s no possibility for green hydrogen.
posted by eustatic at 7:44 AM on February 8, 2023 [3 favorites]


Also, on no account should the oil industry be let anywhere near the management of the exercise.
posted by rongorongo at 7:38 AM on


This is so far from the reality of who is benefitting from the 45Q tax credit... the mind boggles. Is no one looking at how many CCS projects are run by oil and plastics and methane companies? All of them?
posted by eustatic at 7:47 AM on February 8, 2023 [1 favorite]


I'd certainly agree w/r/t cars, but it seems like trains could make use of it. You don't have the same problems developing a huge infrastructure, and caring extra fuel is not as big a problem.

One the other hand trains are the easiest transport mode to electrify as seen by their continous electrification in many places basically since electric power was invented. Adding gantries to most mainlines in even the US would be cost effective (the prime movers are already electric) but rail companies are obsessed with operating ratio over capital investment. It would be crazy to build out hydrogen infrastructure for rail traffic instead of electrifying.
posted by Mitheral at 7:48 AM on February 8, 2023 [7 favorites]


At the end of "Clean Coal" Iverson wrote in 2015 how Carbon Capture was not financially viable, so it needed to

1) obtain massive govt support
2) maintain political hegemony over wind and solar, because wind and solar destroy the market for CCS

And, in 2022, we got the IRA bill from Joe Manchin.

1) increased the massive govt support for ccs
2) forced the leasing of 94 blocks of the ocean on behalf of Exxon. (In areas suitable for wind power)
3) Required offshore leasing for oil /ccs for any wind leasing to happen at all. They can maintain control of offshore leasing, effectively throttling their competition.

Oil companies are not dumb.
posted by eustatic at 7:53 AM on February 8, 2023 [1 favorite]


I'd certainly agree w/r/t cars, but it seems like trains could make use of it. You don't have the same problems developing a huge infrastructure, and caring extra fuel is not as big a problem.

Trains should all be electric going forward. The F=ma on the deceleration and the very large m of a train is just too much to ignore when you consider just how much energy could be recaptured. The fact that only 1% of the US rail infrastructure is electrified should be a national shame.

Short of a miracle in gravimetric density improvements, hydrogen will be vital for planes to continue flying.
posted by Your Childhood Pet Rock at 8:10 AM on February 8, 2023 [3 favorites]


synthesizing hydrogen derivatives (e.g., octane, hexane, various -anes and -enes)

Synthetic hydrocarbons are indeed a thing, commonly called renewable fuels (RF) or sustainable aviation fuels (SAF), which gives you a hint as to which industry thinks this could work for them. This is thermodynamically hard because CO2 needs a lot of energy to be unoxidised (that is reduced) and turned (back) into a hydrocarbon, but it's not impossible at all. It is similar to what plants do naturally. A solar or wind driven input makes a tonne of sense for the process. Done right this has a lot of promise, particularly for "surplus" power that isn't directly needed at time of generation.

RF/SAF can be made from a lot of source inputs and using a lot of methods, including biomass methane, atmospheric CO2, and "gaseous wastes" which I think are mostly the "waste" methane from typical drilling and refining processes. Unlike the CO2 capture, while this is thermodynamically expensive to do, it produces a net useful result that has an identifiable market using easily understandable and renewable energy sources. No handwaving. No need for scams. It is a hard set of chemical and engineering problems, but we know it can be done.

The fundamental idea here is to use a clean, renewable energy source to store that energy as a fuel that can be burnt in a jet turbine or ICE as a direct replacement for petroleum fuel. This fuel source replacement means existing infrastructure becomes closed loop and stops being a net-emitter of greenhouse gasses, not just carbon dioxide, but methane as well.
posted by bonehead at 8:42 AM on February 8, 2023 [4 favorites]


if we are OK about the risk of damage of storing the stored carbon dioxide on the sea bed

I've seen models for what methane bubble releases do in water, and I'm not at all confident that we can handle a potentially much more damaging release of an acid gas like carbon monoxide without major ecological impacts. Whether at sea or more likely in groundwater, being stored in an empty oil reservoir. Unless the CO2 is fully mineralized, that is, turned into solid carbonate rocks, I view this as an ecological timebomb. And so a scam.
posted by bonehead at 8:47 AM on February 8, 2023 [3 favorites]


Potential uses of hydrogen and practicalities of its use have basically been my professional life for the last few years so I have quite a lot of thoughts on this.

First, I agree with basically everyone else that it's not a good idea to use "blue" hydrogen widely except to displace existing industrial combustion of natural gas or hydrogen. That's because:

1) CH4 has a very high equivalent warming impact
2) Leakage from upstream varies (US shale or Russian production very high, UK continental shelf and Norwegian very low) but in the absence of natural gas and natural gas derived products leakage labelling, can vastly change the impact and have to reflect the worst case
3) The best theoretically available capture fractions from AMR (rather experimental) approaches are still not that great
4) The empirically best available capture fractions from installed SMR systems are much lower

That being said, a lot of criticism of the use of hydrogen as an energy carrier is coming from a place of deliberate or accidental ignorance of wider energy systems modelling.

Yes, it is extremely lossy to convert electricity to hydrogen, ram it underground, and then burn it in a turbine for a 1:20 weather driven electricity system event.

Yes, a heat pump with average efficiency / CoP of over 3 is going to consume energy much more efficiently than laboriously making hydrogen, moving it to a boiler, and then burning it.

Yes, the wells to wheels efficiency of BEV is and must be far superior to hydrogen.

However, just noting those things (or publishing papers making those obvious points) is not particularly helpful in the absence of systems thinking.


The hydrogen proponents need to go away until they can come up with a good-faith answer to the objections about hydrogen embrittlement (and other problems deriving from the underlying cause, namely the tinyness of H2 molecules compared to the particles of literally any other substance that humans have to work with) and its implications for storage and transport.

A lot of my work is on the practical consequences of hydrogen embrittlement on existing infrastructure. Embrittlement is an issue and actually very poorly understood. We don't even really understand the mechanism very well. What we do know is that low yield strength steels and plastic pipes have limited vulnerability to it. Countries like Germany which have historically used low yield strength but thick pipes are much better able to do this than the US which uses high yield strength steels and thinner pipes. Most estimates of the re-usability of existing transmission and distribution pipes for hydrogen is very poor and just applies the empirically derived standards for H2 pipelines to existing gas infrastructure and notes that it doesn't match and therefore would need replacement. I think that's very difficult to justify on the evidence, a lot of moderate yield strength gas pipeline is absolutely usable for hydrogen transport should that be required, even if you wouldn't build a hydrogen pipeline that way new-build.

This:

Is an excellent recent overview on what is known about the effect of hydrogen on pipeline steels.

I actually think the compression issues are much more of a downside for long distance transport than the materials issues.


Hydrogen for long term energy storage

The real case for hydrogen, outside the specialist uses as a feedstock, actually comes from electricity system modelling - this in turn drives a scenario where there's an awful lot more hydrogen going around than people currently think and that in turn drives a case for what would otherwise be ludicrous ideas like using it in heating.

The logic essentially works like this:

First, we come up with our most likely future electricity system. Electricity can be looked at it in two ways. Energy-world and power-world.

In energy-world, we think about electricity in terms of kWh which is a unit of energy. These can be priced on a "levelised" basis which includes the cost to build and to operate and to fuel the power plant over time, this is often expressed as LCOE. These units purport to be equal to one another.

In power-world, we think about kW, a unit of power. Specifically, we need a system that has enough kW of supply to match kW of demand at all times.

Batteries and other ways of storing and discharging energy are ways of bridging energy between times and therefore energy to power. The cheaper batteries are relative to generation, the more energy and power worlds converge. In the world of liquid fuels, storage is very cheap and we do not think about instantaneous output very much at all.

We may assume that our future system is based on variable output sources (wind and solar), these have a low cost per unit of energy and this cost may still have quite some declining to do. It's complicated to know whether the recent slowdown in solar module price decrease is due to short term supply chain issues or something else.

We then assume, quite reasonably, that we are smart about our demand and that we ramp it up when we have lots of renewable energy and down when we do not. There are limits to this, mostly relating to length of time - we can all shut our freezers off for an hour but not for 48 hours. Some sources of demand, such as charging EVs are nearly perfect in how much they can be varied. Some others, such as domestic lighting cannot be varied at all.

The variation in production from wind and solar has certain statistical properties which can be measured and studied. Adding both together creates fewer periods of very low output because they are not correlated. If the output from wind and solar over a wide geographic area is sufficiently low, for a sufficiently long period of time, we have a problem. Even if this event is very rare, we still have a problem because a power grid that fails completely but only once a year is not one that is compatible with how we currently operate our civilisation. (if we change that, we make this problem much easier to solve). In general, the statistical properties are such that the more surety you want, the more storage you need and the amount of storage goes up non-linearly. If you only need enough wind and solar to run the grid 40% of the time - that is very easy in most places you don't need any storage. Going from, say, 80% to 90% is very much harder and going from 90% to 99% is terrifically difficult.

That's because if you measure the number of consecutive hours of combined wind/solar output below a given threshold, the longer periods swiftly become rare but not unheard of.

Now, adding wind and solar generation is much cheaper than storage, so it's generally cheaper to "overbuild" such that the system is net over-supplied the vast majority of the time, this is an important point. If you have variable renewable production and the cost of generation is < storage, and the economic cost a black-out is high, then you always end up with a system that is optimised towards having way too much electricity most of the time to avoid the cases where you have too little even occasionally.

(to read more about, look up Marc Perez's work. I don't agree with everything he says but he makes the case for overbuilding very well).

So a battery for daily balancing gets used every day, but what do you do to bridge a 20 day period of nearly zero output on the wind and solar production side? Can you battery your way out of that?

Northern Europe, for example, is prone to periods of cold, overcast, and wind-still conditions from the Irish coast all the way to Urals. These can last 5 days (almost every year) 10 days (rare), 30 days (not unheard of) etc.

Anyway, the implication is that either:

a) You have loads of hydro that you only use as a back-up once every few decades
b) You store energy in expensive batteries and just leave it there for decades
c) You have loads of nuclear and just do away with all this complicated grid management malarky but then you lose the benefits of the cheap-per-unit-energy solar and wind
d) You have huge amounts of biogas that isn't feedstock limited and you store it for a rainy day (maybe but many places just don't have the feedstock to do this!)
e) You store energy in some other form

So if you put that together, you have a system that has deeply cheap and available electricity almost all the time and that is desperately short of it for very short periods. That, to me, justifies a form of energy storage which is very cheap per unit of energy storage, cheapish per unit of peak power, and that can be filled with nearly free electricity during most of the year (i.e. conversion efficiency doesn't matter). Hydrogen production would then be competing with other potential uses of this enormous flood of cheap but unreliable power such as direct air capture (speaking of the thermodynamically eyebrow raising) and not with conventional uses of electricity.

To me, any argument that it isn't efficient is sort of missing the point. Yes, of course it isn't efficient but there is a cost to be paid to move 1kWh produced on a windy afternoon to 1kWh consumed on a windless night. You can pay that cost using a battery and pay little in terms of round-trip efficiency but loads in terms of materials, or store it as underground hydrogen in which case you pay in (in)efficiency, electrolyser capex, and compression energy, but the cost per unit of storage is many orders of magnitude cheaper. Per unit of peak output energy, batteries are better but you cannot make a really cheap battery that takes 200 hours to discharge, there tends to be a narrow range of C rates available.


Transport

As a drop-in replacement for liquid fuels, batteries shouldn't work. The reason they do is that the much lower energy density of batteries are offset by four things:

First, you can recharge them almost everywhere! We already have electricity in our houses, our workplaces, stores, car parks, etc.
Second, the theoretical capability to drive hundreds of miles, refill within five minutes, and then drive hundreds more miles which liquid fueled personal cars have, is just that - theoretical. Nobody uses their car like that and so the fact that batteries make it hard to duplicate this "capability" is not relevant.
Third, the efficiency is a lot better.
Fourth, you dump a lot of complexity and O&M costs.

For trucks, yes this is a hard[er] problem to solve but ambrosen notes that working time regs already constrain how trucks can operate. Unless you use two-driver operation (basically nobody does this except for tiny niches due to the cost), you already need to programme in stops.

You need quite a cable for 1MW+ cables but nothing stops you from having multiple cables, cables on overhead gantries or even just heavy cables - truck charging is not constrained by the same handling constraints that mean that every adult must be able to handle the cable!

Finally, note that hydrogen fuel cell vehicles are actually battery electric vehicles with small batteries and fuel cells to top them up, so a lot of trends that benefit full electric trucks also benefit hydrogen-electric trucks and that cuts both ways.

On the other hand, that's a lot of expensive battery to carry around and hydrogen tank cost scales much more slowly than battery cost.

I genuinely doubt that we will see hydrogen powering ground transport in anything other than niche applications. In marine applications and aviation I would expect to see liquid fuels... which may require hydrogen to produce as an intermediate but there's just so much capital tied up in existing planes, ships, and their engines that re-engineering those to use a gaseous fuel doesn't seem realistic. If you think about the vast, vast quantities of human capital which has gone into the modern miracle which is the high-bypass passenger plane engine and the planes they serve, it just doesn't make sense to throw that away for hydrogen in gas or liquid (lol) form when you can use the hydrogen, carbon, and (lots of) energy to make drop-in liquid aviation fuels.


Heating

Yes, the case for using hydrogen in domestic heating is pretty weak of course, but... if you do postulate an energy scenario where despite attempts to arbitrage it away, we have ridiculously cheap electricity producing vast quantities of storeable hydrogen over the course of the year, and our electricity system is most desperately stressed by heating loads in the winter, then it doesn't seem so unreasonable to imagine that some would end up displacing expensive-at-the-peak-time electricity.

The evidence concerning the use of hydrogen for home heating is almost entirely negative. Jan Rosenow found 32 articles for his literature review in Joule, published in Oct,2022. You should be able to access it via researchgate.

I don't really like review papers but I hated this one more than most. Most of the cited papers are pretty poor anyway so no reason that a review paper would make anything better out of those ingredients. None of those papers makes any attempts to do a systems-analysis, they just look at the perspective of the resident assuming current electricity and hydrogen prices and price dynamics remain the same. If everyone has to pay for their electricity on a half-hourly basis, the lowest-cost point shifts away from heat pumps. That's especially true for older properties where it is highly likely that heat pumps will have to operate away from their optimal flow and return temperatures in order to maintain comfort on the coldest days - that doesn't affect the average CoP over the year so badly but it can mean concentrating electricity usage on a total-system level in some very congested and expensive time periods. If electricity price is strongly correlated with national and regional heating demand (and the more heat pumps you put on the system, the more it will be) then you can get into some very expensive input-electricity scenarios that just aren't captured here.
posted by atrazine at 9:11 AM on February 8, 2023 [18 favorites]


If you're already planning to hike up a huge activation energy mountain and synthesize a versatile, storable chemical fuel from base feedstocks like water or carbon dioxide, why not at least make a drop-in fuel replacement like an RF or a SAF, pure octane or nonane, for example, rather than make a hard to handle fuel like hydrogen? One requires absolutely no additional investment to continue using existing and well-understood infrastructure, the hydrogen option requires a lot of technology we don't know a lot about using, with potentially major issues like embrittlement and through-solid leakage.

It seems like a not-so-hard choice to me, but I'm just a hydrocarbon chemist.
posted by bonehead at 9:17 AM on February 8, 2023 [3 favorites]


bonehead,

Do synthetic pathways to the alkanes not use hydrogen as a feedstock?

I was under the impression that they were (via syngas and then Fischer Tropsch). If not, then no you wouldn't need it at all for aviation. The idea of using anything other than drop-in liquid fuel replacements for aviation is so crazy to me that I always feel like I must be missing something when people propose it.
posted by atrazine at 9:58 AM on February 8, 2023


Actually I think I misread your comment to be entirely about aviation when it isn't.

I mean, basically: yes. Any process that has the following characteristics:

-Needs lots of input energy
-Storable output

Can be used to soak up excess electricity. If the output is also readily convertible into electricity, then even better. Truly vast quantities of gas can be stored in depleted wells (i.e. one or two depleted UK gas fields would provide all the contingency store required) which is more compact in terms of land use than storing liquid fuels, especially for a 1:20 year scenario.

The reality is probably that a lot energy dense molecular storage of various kinds will find some kind of economic balance. Maybe it would be better to just build a few nonane tank farms instead of messing about with unproven behaviour of hydrogen in depleted gas wells.
posted by atrazine at 10:03 AM on February 8, 2023 [1 favorite]


atrazine, many of the exact processes are secrets or patents, but some at least work from water as a hydrogen source, doing catalyzed steam reforming. I'm sure there are routes that start with H2, but the literature and whitepapers I've seen generally starts with water.

I think it's a fair comment to say that, at least for now, the main market for RFs is the aviation sector, who largely see it as their only real way to bring their industry to net-zero carbon energy use. RFs will probably be too expensive to use in other sectors, like road or marine transportation. I know the marine commercial sectors would love an affordable renewable fuel like a synthetic diesel, but they're way too price sensitive for that to happen in the foreseeable future.
posted by bonehead at 10:11 AM on February 8, 2023 [1 favorite]


We should adopt sail and nuclear for water transport because nothing else makes sense. We'll never ship too much by sail of course, but we should halt most international shipping anyways.

We'll hopefully abandon frequent air travel entirely, but if not then maybe nuclear power aircraft. lol
posted by jeffburdges at 10:52 AM on February 8, 2023


I used to read news articles supplied by Google algorithms of what it thought I wanted to read. Because I used to look at articles about hydrogen it decided to send me lots of articles about hydrogen as storage and fuel.

There was a constant stream of articles listing 'hydrogen breakthroughs'. Suspiciously, they were usually articles from petroleum trade magazines.

I'm not convinced that hydrogen is useful as a fuel source for transportation or as a storage medium.

California has been paying 100s of millions of taxpayer dollars to push hydrogen as a fuel source for cars. After decades of this, there are only a few thousand cars and 55 stations in the state (there are 14 million cars, 10 thousand gas stations, 28 thousand level 2 chargers, and many thousand level 3 chargers).

Why? The cost of hydrogen is almost irrelevant--hydrogen is extremely expensive to handle. You have to compress it to 10,000 psi (about 700 bar) and set to below freezing temperature to deliver it to the car. This equipment is very expensive, often > $1 million a pump. And gas stations can barely keep a 40 psi tire pump working, so you can imagine the costs to keep this 10,000 psi and hydrogen freezing pump equipment working. Very high capex and very high opex. That's why hydrogen at the pump in LA is about $26/kg right now even though you can buy hydrogen on the market for < $4 kg. And it is only required to be 33% renewable. So you have people paying the equivalent of paying $20/gallon for gasoline, and 66% of it is still polluting in its creation. It makes absolutely no sense at all. The only reason it exists is because of lobbying to create the tax subsidies that are paying for it all.

What about for storage? California has a lot of solar and wind, so much that there is basically an excess at certain times of the day. So there's an enormous incentive for storage. It almost like printing money. Lots of investors are taking advantage of this and are building out energy storage facilities. One even built one that consists entirely of used EV batteries from Nissan and Tesla cars, and they are now making $1million a year. There are lots of approaches for energy storage, but despite atrazine's dismissal of batteries as expensive, that is what most of the investors are choosing to build their storage plants. Yes, there are hydrogen storage plants being planned, but I think these are also being driven by taxpayer money.
posted by eye of newt at 11:28 AM on February 8, 2023


We should adopt sail and nuclear for water transport because nothing else makes sense.

Experiments with sails are happening with companies like Maersk, but they're assistive rather than primary means of transport for cargo vessels. They are selling sail-assisted oil tankers right now.

I can't see nuclear ever being available to the merchant marine for a whole bunch of reasons: cost, ecological impacts and security concerns, but most importantly because of the social/political hurdles. Shippers live and die by insurance---I can't see anyone insuring a nuclear civilian cargo vessel.
posted by bonehead at 12:23 PM on February 8, 2023 [5 favorites]


Hydrogen may be useful for ships, trains, and planes, and for storing excess energy generated by wind and solar facilities.

It doesn't look likely to become a fuel of choice for cars (notwithstanding Toyota's efforts to make it one), or for home usage.
posted by Artifice_Eternity at 2:32 PM on February 8, 2023


Using hydrogen directly as fuel, or storing it for long periods as a fuel for backup generators (gas turbines?) still runs into the problem that storing hydrogen is like storing nothing else in human experience. It migrates into and rots practically any substance you can think of, and all @atrazine offers in response is "well, yeah, that's a big problem, and very poorly understood. But we're working on it!"

Reacting it with carbon to make alkanes and storing those in depleted wells? Can the refilled wells be sealed off to make them leak only at a tolerably low rate? That seems more plausible, though you'd want to be using carbon captured from atmospheric CO2, and as @bonehead admits the technology for just the alkane synthesis part of that is still trade-secret lab-scale. Once you have accomplished the small matter of engineering involved in turning that into an industrial plant that can run much of the time turning excess solar and wind into octane, there are some maybe somewhat larger problems involved with guaranteeing the proposed storage method. I suspect there's significant uncertainty with that.
posted by Aardvark Cheeselog at 4:53 PM on February 8, 2023 [3 favorites]


There's no problem with storing octane. This is just the chemical name for one of the major components in gasoline. That's what RFs are: gasoline and kerosene and perhaps diesel made from renewable feedstocks, not extracted from the ground. Sorry if that wasn't clear.
posted by bonehead at 7:40 PM on February 8, 2023 [1 favorite]


What about for storage? California has a lot of solar and wind, so much that there is basically an excess at certain times of the day. So there's an enormous incentive for storage. It almost like printing money. Lots of investors are taking advantage of this and are building out energy storage facilities. One even built one that consists entirely of used EV batteries from Nissan and Tesla cars, and they are now making $1million a year. There are lots of approaches for energy storage, but despite atrazine's dismissal of batteries as expensive, that is what most of the investors are choosing to build their storage plants. Yes, there are hydrogen storage plants being planned, but I think these are also being driven by taxpayer money.

Storage is really a range of markets which are best characterised by the frequency of use.

For intra-day energy movement, you want something that's got great round-trip efficiency most of all and you get to recover the capex over a lot of cycles. So if it costs $100 / kWh usable capacity and you charge / discharge the system every day (as you would in a solar dominated system) then over a ten year period you get 3650 cycles to cover that capital cost (I know that battery lifetime is more cycle bound than calendar age but with good management of charge state, rates, and accepting degradation of performance that becomes less of a factor).

I don't think anyone doubts that the intra-day role will be played by electrochemical batteries of some sort.

The issue is that if you pull out the frequencies over which energy demand net varies, you get the following:
-A really big diurnal component
-A substantial seasonal component, especially in temperate climates

If you now map variable renewable output onto this to get a net figure:
-The diurnal component is even stronger because of solar
-There is still a strong seasonal component, complex and varies by location with prevailing wind patterns
-You get this very nasty tail of rare-but-non-zero recurrence periods where demand is high and there is little sun and there is no wind

Batteries solve the diurnal pattern. Yes, they're expensive but alternatives to wind+solar+batteries are *also* expensive.

The regular seasonal in many places can be bridgeable through sufficient north-south interconnection, although in Europe you hit the Med before you get far enough South that net energy demand isn't higher in the winter.

It's the 1:10, 1:20 year recurrence of cold, windless, overcast that is not rare enough to ignore but rare enough that if you provision storage for it, that storage may sit around unused for a decade or more.

If you have lots of hydro then great, smoke 'em if you got 'em and your problem is essentially solved. (although see Norway this year for complications to that)

Otherwise it gets really hard to see how you solve the problem.

Yes, demand side response is great but most DSR opportunities are clustered at the daily / weekly time scale as well.

So it's not so much that hydrogen is a great storage technology as that it's one of a rogue's gallery of "maybe" technologies that might break through what would otherwise be a barrier to really deep decarbonisation.

Hydrogen storage in salt domes is a very well understood technology which is many decades old. What is new is geological storage in depleted gas fields and the behaviour of metallic pipes of certain types in hydrogen atmospheres.

If you have about 30% - 40% grid capacity as nuclear then you tend not to need storage for low frequency events like this (you still need daily storage) but that's a lot of nuclear to build.
posted by atrazine at 4:22 AM on February 9, 2023 [1 favorite]


Otherwise it gets really hard to see how you solve the problem.

I don't think solar and wind vary that much. See a one year trace of renewables in the Australian grid, at a weekly level.

At a large grid scale level (multiple states) there's always opportunities for hydro to fill in the gaps, both at the diurnal and seasonal level. Hydro even replaces lost solar in winter because there's increase precipitation, and solar replaces hydro in dry spells. With a large enough grid the geographic diversity should ensure total wind and solar never drops too low.

I've always thought the solution is to simply assume suboptimal generation and overbuild. For example, with solar panels, we know there are many more cloudy days in winter, impairing generation. So it's typical to match say 6.6kW of panels to a 5kW inverter, so you get that extra generation in winter without spending money on a larger inverter that only really gets utilized in summer when you don't need the extra power anyway.
posted by xdvesper at 5:43 AM on February 9, 2023 [1 favorite]


The first part of the solution is definitely to "over"build ("over" in quotes because it's actually optimal). The problem is what happens when the output drops so low that even a 2-3x overbuild doesn't generate enough electricity.

In a way, this is its own solution - if a 2-3x over build (that figure is from Perez's work on Texas, New England, and Californian solar + wind generation) is cost optimal because the cost of additional generation is much less than the cost of storage, you inevitably get a system that is "long" excess electricity almost all the time anyway. It also doesn't solve the problem of what happens when you're multiplying 2-3x by 5% or so of notional capacity which is that this is still a very small number and that going to 4x or 5x isn't enough to "overpower" a very low %.

Solar dominated grids vary by less than wind dominated grids - so Australia and South West US tend to have much more predictable outputs than NW Europe. The basic cycle is always diurnal with some cloud-cover and day-length overlay. Wind is more variable and there are periods where output over very wide areas (i.e. reasonable areas for grid interconnection) is less than 2% of nameplate capacity for days to weeks. Absent snow-cover, solar never drops that low for that long.

In European power forecasting, we refer to these periods as dunkelflaute and meteorologists refer to them as anticyclonic gloom. This paper looks at some shorter (few days long) periods of anticyclonic gloom. That paper uses a threshold of onshore, offshore wind, and solar all being below 10% of nameplate.

Every year has about 150 hours or so like this, what's a bit rarer is that they last longer than 24 hours but this does happen.

In February of 2010, for example, much of Europe was hit by a series of February storms that reduced renewable generation to almost nothing.

Below is a number of consecutive hours where output was less than the given % of nameplate capacity based on GB network data, I've also shown how many distinct 24 hour intervals exist in the dataset (2009 to 2023) where combined solar and wind production is at or less than the quoted %.

1% 35 hours / 3 such days
5% 148 hours (6 days) / 38 such days
10% 156 hours (6.5 days) / 138 such days


If we relax the constraint to 20% then we have the following event from May 2010.
20% 351 hours (14 days) / 336 such days

While I think we can anticipate the frequent days when total output is at 20% or less of max capacity just by building more, as we get deeper and deeper into rare events, the level of overbuilding gets a-physical and slightly ridiculous and it is better to come up with a way of storing energy from all those hours when we have lots of spare energy.
posted by atrazine at 7:49 AM on February 9, 2023 [2 favorites]


Are well-understood non-fossil, non-nuclear technologies like hydro/pumped storage/geothermal incapable of providing enough power to handle that kind of intermittency?
posted by Gerald Bostock at 8:57 AM on February 9, 2023


Atrazine: Its really interesting to see those calculations, in terms of quantifying how rare and long those low output times are. It reminds me of sailing: great most of the time but with moments of being in the doldrums - you need to either spark up the outboard or go and have a snooze.

Are well-understood non-fossil, non-nuclear technologies like hydro/pumped storage/geothermal incapable of providing enough power to handle that kind of intermittency?

One other, I find interesting, is the idea of sand batteries - use your excess renewable energy to heat sand (not fussy what kind) to a few hundred degrees - and harvest that heat hours or months later? The linked article is about Finnish company Polar Night whose foundation came from the question "“Is it possible to build an energy-self-sufficient and cost-effective hippie commune for engineers using only solar power?" - or less directly “If you want to make a dirt-cheap battery, you have to make it out of dirt.”
posted by rongorongo at 10:19 AM on February 9, 2023 [3 favorites]


@ bonehead
There's no problem with storing octane. This is just the chemical name for one of the major components in gasoline. That's what RFs are: gasoline and kerosene and perhaps diesel made from renewable feedstocks, not extracted from the ground. Sorry if that wasn't clear.
Hmmm I would have hoped that my casual references to "alkane synthesis" would have been a clue that no, there was no confusion on my part about what octane is. If that is the reason you did not respond to the substance of the comment, namely that storing megatons of octane for very long periods in pumped out gas wells is at best an unproven technology, not to say a highly speculative one. What's the annual expected loss of octane from one of those wells, and what is the climate impact of that?

This is the problem with hydrogen fuel. There are all kinds of really big problems with using it at any kind of scale, and the people who are advocating that just kind of glide past that objection with "yeah we know, we're working on that." Which just is not fucking good enough.
posted by Aardvark Cheeselog at 11:52 AM on February 9, 2023 [2 favorites]


Octane (or most of the other RFs under consideration) is fairly stable and isn't at all water soluble. Hydrocarbons have been kept sequestered for entire eras of the Earth's history in geological structures. Octanes are significantly abundant in crude oil.

The US already stores crude oil in caves/reservoirs for the National Strategic Reserve. The US strategic reserve is a bit greater than 100 Mm3, which it has maintained without major incidents for decades. There's no reason to think a synthetic fuel could not be managed in the same way.
posted by bonehead at 12:49 PM on February 9, 2023


Are well-understood non-fossil, non-nuclear technologies like hydro/pumped storage/geothermal incapable of providing enough power to handle that kind of intermittency?

Hydro is the absolute dream from an energy POV - it's not consequence free environmentally but it solves so many problems. Unfortunately a lot of the best sites are built up already.

There is a "spirited debate" among the hydro-experts which I'm not qualified to understand about just how much low-head pumped storage could be built. Some people say absolute loads, some say that's complete nonsense.

Sand batteries are very cool! At first it seems like that couldn't really work very well in practice but once you run the numbers it's really amazing what can be done with Our Friend the Sand Grain. The historical engineering challenge has been that low-grade heat is very inefficient at getting back into electricity but if your big swing demand is heat in the first place then you don't need to do that.

Up to now, we've been using cheap gas as our outboard and actually we can get to pretty low grid carbon intensities with just wind, solar, gas. The idea has been that we would phase down gas and replace with batteries and we could get down to some 80g/kWh style grids without too much trouble. It's just that you hit an exponential wall going much below 50 g/kWh that way since the gas is still a major GHG contributor (and those figures don't even include leakage) and the battery capacity starts going exponential as you get closer to zero.

This is the problem with hydrogen fuel. There are all kinds of really big problems with using it at any kind of scale, and the people who are advocating that just kind of glide past that objection with "yeah we know, we're working on that." Which just is not fucking good enough.

It seems to be accepted by everyone for the other final 20%-30% of decarbonising our civilisation. How do we decarbonise steel? Cement? Fertiliser? Marine transport? (aviation we could just cut back on massively if we had to). In every case the answer is - we don't know, there's a bunch of ideas and we don't know if the winning one is in that list. We don't actually know whether we can run a society that looks anything like ours now without using the atmosphere as a carbon sink for free.
posted by atrazine at 2:50 PM on February 9, 2023 [2 favorites]


How do we decarbonise steel? Cement?

There's been a few posts on the blue on using mass timber as a net-zero carbon alternative to steel and cement, even for skyscraper scale structures. As per some of the comments, it's more fire resistant than steel or cement - When exposed to high temperatures, steel loses strength and begins to deform and fail catastrophically (eg the WTC collapse). Cross laminated timber not only retains its structural strength at high temperatures, it also self protects against combustion - the surface chars to black carbon. Mass timber is much less conductive than steel, so transmission of heat through the structure is also prevented.

---

Metafilter Sep 2020 - Surrounded by giant slabs of cross-laminated timber

Metafilter Oct 2018 - Cities out of wood
posted by xdvesper at 3:37 PM on February 9, 2023 [1 favorite]


Short of a miracle in gravimetric density improvements, hydrogen will be vital for planes to continue flying.
If you could somehow put hydrogen in the wings without them icing over from the cold then absolutely the gravimetric density would be very attractive for aviation. I fear there may not be a good solution to the icing problem though.
posted by mscibing at 7:32 PM on February 9, 2023


The regular seasonal in many places can be bridgeable through sufficient north-south interconnection, although in Europe you hit the Med before you get far enough South that net energy demand isn't higher in the winter.

The Mediterranean isn't an insurmountable barrier. Currently an undersea interconnect between Egypt and Greece is being constructed (that bypasses Crete) and there are existing connections between Spain and Morocco. There are several other reasonable paths across like from Algeria via Sardinia and to Italy via Sicily from Tunisia and even directly between England and Morocco.

Seems crazy that solar power from Egypt might one day power the lights in Belgium but it is possible.
posted by Mitheral at 2:48 AM on February 10, 2023 [2 favorites]


Ars Technica: The rise of green hydrogen in Latin America
posted by bonehead at 11:29 AM on February 10, 2023


It isn't but I think geopolitics will make that very challenging given the real-time interdependence required from having a linked grid like that.
posted by atrazine at 9:19 AM on February 12, 2023


There's been a few posts on the blue on using mass timber as a net-zero carbon alternative to steel and cement, even for skyscraper scale structures.

I am pretty excited about the possibilities of mass timber. But it's not going to completely replace concrete. Building foundations will still need to be made of concrete, as will a lot of other structures.

And concrete is indeed a big contributor to carbon pollution. However, we can make concrete greener.

I don't have time to round up links now, but in recent years, various companies and researchers have shown that it's possible to: (1) use greener raw materials and energy sources for producing concrete; (2) capture and sequester the CO2 normally emitted during concrete production; and even (3) infuse the concrete itself with added CO2 -- which strengthens it and makes it a good carbon sink.
posted by Artifice_Eternity at 9:16 AM on February 13, 2023


For anybody who enjoyed the original Fully Charged podcast on hydroden in the FPP - there is now a follow up with Ketan Joshi - talking about the (various) cons in play with Carbon Offsetting.
posted by rongorongo at 3:30 AM on February 17, 2023 [1 favorite]








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