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Cheap, green hydrogen would be a breakthrough in clean energy

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Re: Cheap, green hydrogen would be a breakthrough in clean energy

#171

Post by raylad »

ggm wrote: post #147

The FF industry is leaping (has leapt, historically) on CCS as a getout clause and has sunk french metric tonnes of money into CCS. So far, its uneconomic except for the specific use of pumping gas into wells to make them more productive, which leads to more fugitive gas. No significant CCS experiment worldwide has achieved its goals as sequestration. The one in Western Australia releases so much CO2 it has to pay a…

I think you are probably right, but some references would really be helpful. Could you share any that you have handy?

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#172

Post by ncmncm »

UnchartedSystem wrote: post #137
ncmncm wrote: post #110

Earlier quoted context omitted.

Guess you mean dimethoxyethane, or "glyme". To "extract bitumen" appears to mean mine tar sands for hydrocarbons. I expect demand for mined oil to decline to the point where only the absolute cheapest producers of it will be able to stay in business. Extracting from tar sand will be right out.

I mean dimethyl ether: DME. Unfortunately, I really doubt we are nearing a collapse in demand for oil. This technology seeks to convert the transportation industry to safe, cheap, and green hydrogen power, but bitumen derived products are used as an industrial feedstock for countless products that make modern society. This technology can reduce the CO2 emissions of extracting and distributing bitumen by 85% - >100%,…

Both are called DME. Only one is described on its WP page as principally a solvent. So, you probably should be more specific when describing your process, to avoid misapprehensions.

When we have no need or desire to oxidize mined hydrocarbons for heat, our remaining demand for mined hydrocarbons (e.g. to make into plastic) will surely be less than today. Then, the most easily obtained natural hydrocarbons will be the ones we mine, because we are not wasting them by oxidizing them to CO2, water, and heat.

Unless there is no bitumen dissolved in that readily obtained oil?

It is just possible that hydrocarbons made from gathered and cracked CO2 will end up cheaper than fractions of extracted oil. But I have doubts.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#173

Post by ncmncm »

tambourine_man wrote: post #154
ncmncm wrote: post #105

Earlier quoted context omitted.

Handling LH2 is really not so different from handling LNG, which we do in the millions of tons.

It’s very, very different: −160 °C vs -250 °C and liquid density of 450 vs 70 kg/m3

Both are easily carried in a Dewar flask. LH2 takes up more room, but that is just a matter of how big the ship carrying your flasks is, and how many of them. The number of kg in a flask of some volume is much less, but you also need to oxidize many fewer kg to get the kWh you paid for. The ratio is not 1, but is much less than 450/70.

There is nothing special about the size and laden mass of the LNG vessels we use. It was chosen by immediate convenience. Details of vessels for LH2 will be chosen the same way.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#174

Post by ncmncm »

ClumsyPilot wrote: post #120
ncmncm wrote: post #102

Earlier quoted context omitted.

When electricity op-ex is free, as from panels, electrolysis is too.

Thats like fantasy ecobomics - you have to consider electricity at market price for the comparison to be meaningfull. Electricity is currently much more expensive than it was last year. Aluminium refineries use OP-ex heavy, so the day your dream of cheap electricity materialises, aluminium will become nearly free

Yes, as energy production prices fall, prices for commodities that depend on it will, too. Aluminum is today "nearly free" by standards of a century ago. We will still need to mine bauxite or collect recycled cans, and handle ingots.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#175

Post by ncmncm »

tuatoru wrote: post #152
ncmncm wrote: post #99

Earlier quoted context omitted.

Hydrogen embrittlement is always hyped to the sky. It is not a serious problem unless you are trying to keep warm, gaseous hydrogen under high pressure. So, don't. Furthermore, aluminum is quite resistant to embrittlement. Of possibly greater moment is that it leaks, and has ~200x GHG over CO2 (including secondary effects). Leaks are not dangerous in the open, or in confined places with positive airflow, but punishme…

> Of possibly greater moment is that it leaks It leaks very readily, it ignites very readily, it burns with a wide range of air:fuel proportions, it burns with a high flame speed, and it burns hot. Hydrogen is ... not a good choice for something to reticulate widely around the world. Edit: That's leaving aside its low energy density. You need three times the volume of hydrogen as natural gas for the same quantity of…

Yet, millions of tons of hydrogen are today produced, transported and used.

There is nothing special about the volumetric energy density of NG. H2 has to move faster, if carried in the same pipe for the same use. Its lower viscosity means it can.

Municipal gas networks used to carry "lamp gas", a mix of CO and H2, in cast-iron pipes.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#176

Post by beambot »

jhallenworld wrote: post #168

I'm interested if you could have a hydrogen stove, or hydrogen space heater- just as diesel, kerosene, propane, methane, electricity, alcohol, wood, and coal are all viable. What practical problems would arise? For example, gasoline camping stoves exist, but are too dangerous for indoor use. If hydrogen is widely available, surely someone will want to do this.. This is what the flame looks like: https://www.youtube.c…

For heating, you are probably better off converting to electricity (burning or fuel cell) and driving a high-COP heat pump. Good heat pumps are ~250-300% "efficient" at "converting" electricity to heat.

(Efficiency isn't in the Carnot sense, and heat pumps move heat rather than generating heat... Semantics, but point stands.)

For example: I recall reading that it is more efficient (ie BTUs generated) to use natural gas peaker plants generating electricity to drive a heat pump than to run a furnace. (Except at very low temps where COP drops quickly.)

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#177

Post by ncmncm »

Jistern wrote: post #100
ncmncm wrote: post #97

Earlier quoted context omitted.

Ammonia will not be used in urban vehicles. It will be used in farm equipment, and in place of bunker oil in ships, and burned in combined-cycle turbines in times when wind and sun are not providing, and other, cheaper storage has been used up.

Ammonia seems too dangerous. With cheap electricity from solar and wind, cheap hydrogen seems like a better answer. Sure, it's not a perfect answer, but it seems better because it seems much safer. As recently as approximately 200 years ago steel was very expensive, as was aluminum. Now both of those materials are cheap and used in a plethora of applications. Cheap electricity will similarly enable us to cost-effecti…

A safety argument does not favor consumer-level use of hydrogen. Nor, of ammonia.

But synthetic liquified hydrogen, produced at airports from power delivered on transmission lines at times when power is cheapest, and banked, will certainly come to drive aircraft where cost matters.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#179

Post by Gibbon1 »

photochemsyn wrote: post #125

Using hydrogen made from electrolysis of water (using solar/wind inputs) as a fuel for electricity generation is basically a futile cycle, and the only advantage would be temporal storage. For short term storage (hours/days) batteries are far more efficient. For long term storage, hydrogen is a bad idea other than as feedstock for production of longer-chain hydrocarbons (Fischer-Tropsch synthesis) or methane (Sabatie…

> is for steel production by the H2-DRI-EAF method

You can electrowin iron at about 80-90% efficiency.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#180

Post by rini17 »

ncmncm wrote: post #69
Barraketh wrote: post #52

Ammonia has been mentioned a few times in this thread, but I will expand a bit, because I believe it is the most promising hydrogen-based approach. Essentially, the idea is to use ammonia directly as fuel. There is an ARPA-E funded project (that I'm currently failing to find) that cracks ammonia into hydrogen and nitrogen using heat. They claim that they can create a mixture of H2 and ammonia that will burn at any re…

Diverting money from building out renewables to building nukes, for whatever purpose, brings climate catastrophe nearer. If ever there was a process forgiving of intermittently available energy, it is chemical synthesis. The same money spent on wind and solar would produce a lot more ammonia. Conversion losses don't matter much when marginal cost of generation is near zero, as we get with renewables, but very much no…

Technically it may be forgiving, but not economically. Imagine electrolyzer or ammonia plant that uses only 20% of full capacity on average because of using only peak electricity surplus. The rest 80% is basically wasted. Classical plant with higher capacity factor might still be more profitable even if it uses more expensive electricity.
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