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Hydrogen Dreams or are they ?

Helios
There is no doubt that Hydrogen grabs most headlines in clean energy promotion , seems all so simple the fuel cell can work with H2 gas and air and produce a decent amount of electrical energy .Things start getting a bit different for trying to move heavy loads or where large amounts of power are needed as what is termed the energy density starts to become important , Diesel has a very high energy density and liquid fuels in general give battery/fuel cells a good run for the money in power terms. 

Things are changing , but fuel cells remain at around 60% efficient and bit more for the very hot solid oxide ones.

There is also the development of Hydrogen to be blended in natural gas mixtures for use in Gas turbines at around 20% by volume which has been successful and now the 100% hydrogen gas turbine is being developed , given gas turbines have recently broken the barrier for heat engines with 64% efficiency ,then this could well replace the fuel cell.

The main problem with hydrogen and particularly liquid hydrogen is the energy used to get it to liquid , 95% of all the worlds hydrogen used in mainly ammonia production comes from the steam reforming/gas shift reaction of natural gas which creates CO2 , 1000kg of liquid Hydrogen produced by this method produces 9-12 tonnes of CO2 (CO2 is quite heavy) , efficiency of energy in ammonia plants has improved but 1000kg of Ammonia uses 27,000,000 KJ , But here's the strange thing there is actually more Hydrogen in 1000m3 of Ammonia than in 1000m3  of liquid Hydrogen (146 kg of H2 in 1000m3 of Ammonia vs 71kg of H2 in 1000m3 of H2) . To keep it liquid great pressures are required for Hydrogen as well as vessels needing low thermal loss properties . A typical H2 fuel tank will need to be able to handle 350 bar which isn't far off the sorts of pressures found at the sea bed where the Titanic now rests , in old money that's 5000 lbs per sq inch.

according to IEA stats

1.4 GT of CO2 comes from the chemical industry

2.3 GT of CO2 comes from cement making (where calcium carbonate is heated/sintered driving off the CO2)

2.1 GT of CO2 from steel making

However the IEA stats don't really delve into the CO2 of steam reforming of natural gas , if we add the CO2 from oil the unit of the Barrel (around 40 us gallons 159 litrs ) produces a minimum of 317kg of CO2 and we use 95,000,000  Barrels a day.

1 Giga Tonne of CO2 is around 505,000,000m3 of CO2 , coal fired power stations put out around 10GT of CO2 globally


So back to Hydrogen , how much Hydrogen is made annually … mmm this is a tricky figure to get hold of and hoping this is correct I found 164,000,000,000 KG of H2 are produced every year mostly (95%) by steam reforming of natural gas so I get that to (9-12 tonnes of CO2 per tonne of Hydrogen) to 261 to 348 million tonnes of CO2 for making the so called clean fuel Hydrogen (or 131-175 million M3 of CO2) 


Flares , no not my fashion statement from the 1970s but the flaring of CH4 from gas and oil wells as part of the extraction process world bank report today has 150,000,000,000 m3 of natural gas flared off annually , enough to meet the gas requirements of sub Saharan Africa , which is kinda wasteful even if pretty in the night sky.


If we move to electrolysis of water current PEM technology claims to convert 75% of the electrical input , the hot alkaline variant 85% , but 1kg of Hydrogen needing 60kwh of electrical energy to make , soo 1000kg of H2 would require 60,000 kwh , so 164,000,000 tonnes of hydrogen for Ammonia I get to 9,840,000,000,000 KWh and this produces CO2 unless from a renewable source . (unsure if figure quoted is inclusive of 25% electrical loss or not if so 1kg of H2 would be 80kwh and not 60kwh)


Its getting complicated which direction to take , more electricity to make green hydrogen , more electricity to power the electric car  , hows the world going to do this ???

Well perhaps a start is for Hydrogen from water electrolysis to make Hydrogen for Ammonia then at least that's the 261-348 million tonnes of CO2 from ammonia taken care of. 

mmm 2,300,000,000 tonnes CO2 from cement making , I mean wow gee if we could only do something with that ?
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    Here is a little bit more information on the hydrogen powered trucks from The Engineer:

    https://www.theengineer.co.uk/hyundai-xcient-fuel-cell-heavy-duty-truck-switzerland/


    They are 190kw rated and carry 32kg of hydrogen. As stated in the previous article this experiment is possible in Switzerland due to the high road tax on commercial vehicles which is waived for 'zero emisions'. They will certainly have to cope with many hills. Is a tank of hydrogen any worse than diesel or other compressed gas when you are in the middle of a long alpine tunnel?

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    I think for CNG and LNG CO2 emissions are about 25% that of diesel , but crucially no particulates at pm 2.5 , NOX I think is reduced by 80% .. Dont know what sort of HGV unit they have but guessing similar to Uk type for turning circle , 190 kw I dont think works for the heavy loads so at a guess they are de rated for maybe 20000-30000kg 

    a 450hp diesel would be 335kw , and a 32kg tank may well suite swiss journey patterns which may not be long 300 mile jobs . A 32kg tank i think is around 440 litre for hydrogen , and it gives a range to fill up of 224km , as for the tunnel question hydrogen may be cleaner , but its if water produced and icey conditions can be dealt with and given altitude of some passes , the hydrogen (which will be at very high pressure) will need engineering , which knowing the swiss should be pretty good .
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    The frrst double decker hydrogen bus has gone into service , and reports of hydrogen train test being succesful has also rolled in (although strangely test seemed to involve an empty train) and some countries are going big into Hydrogen , best of luck to them my personal view is that it will have problems as a transport fuel , but hey what do I know ?

    Could it change ?? well some aspects of fuel cell physics will not , but if the hydrogen fuel cell becomes more efficient ?? may be in transport but even then it might be selective , I think a sub 200 mile range 2kg of hydrogen tank small call or even 2 or 3 wheel vehicle will work in many situations , how much per kg of hydrogen is an interesting possible decider , but my thoughts for now are electric will win as personal transport (again as a sub 200 mile vehicle) ,out IF, and its a very big IF , we get an easily recyclable battery unit and I still dont rule out some other forms of electrical storage other than Li On , that are less problematic at the point of re cycling .Both hydrogen and electric vehicles have increased wieght so will get more tyre wear , and tyres use a lot of fossil fuel (noting new rubber plantations will be needed for true eco credentials) , also the wieght will affect insurance costs , so people will pay more per mile by car in the future , and the EV perhaps gives at least some cost reductions for car owners, but even if you have the cheapest hydrogen you can make your still putting it in system that converts around 60% of that into electricity for the motors , a battery does this at 80% , if electricity becomes cheaper, then Hydrogen as fuel will be in trouble. If a fuel lasts the same amount of time as battery pack then thats not good . I think it has to be slugged out , already a cheaper fuel cell has been designed .Where i think Hydrogen will work is if its used in energy systems to supply/support the grid although I would think using it to replace hydrogen from fossil fuels for the chemicals industry will be the FIRST PRIORITY , which in turn will make hydrogen for vehicles expensive until we can make it cheaply , simply because the chemical industry uses so much hydrogen ..
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    I think that the solutionsfor transport in the future will be different for different areas. A compact country with compact towns can use directly fed electric public transport, trains, trams, trolley buses, quite effecively. Large countries with urban sprawl will require independant transport using some storage medium, batteries, hydrogen, ammonia, etc.

    Planning can certainly improve urban areas but cannot do much about th edistances between towns and cities.
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    Electric trains have huge conventional fuel cost when building the overhead lines. Here in the South West of UK the cost of "electrifying" the GWR line between London and Plymouth is astonomical and the disruption to traffic is immense because nearly every bridge over the line has to be rebuilt to clear the overhead wires. It is 300% overbudget I believe, and years behind schedule. More billions spent when the original Diesel 125 Deltic trains were faster and cheaper than anything on offer! You might say that electric traction will be cleaner, but is the overall thing cleaner or cheaper? I don't know, but it will take many years to show any overall gain.
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    Hi Roger Bryant

    I would think for compact towns , that either underground or tram dedicated lines for passengers work well , perhaps some light frieght is also possible . for larger distances then it depends if track pathways taken up by freight , but I think rail wins out on cost grounds , planning I think for uk is about at limit too much greenfield and greenbelt has already been built upon , so pretty impossible to plan new cities and transport .

    I did a liitle calculation and its cheaper to run 50 chinook helicopters on fas london to briminham shuttle than build HS2 and now they have just chopped down a previous great tree winner , a very old pear tree. 

    on topic it seems fuel cell mk3 is being designed by toyota , good luck to them ...
  • 0
    Hi davezawadi 

    It is unfortunate that so many energy engineers have gone down the wrong corporate sensibilities , electrification looked so useful for railways and now i have seen other views and regret my pro electrifcation feelings , although it is true it does give the greater passenger transit models , your quite right it would save a lot of cost and it may well be that an expensive railway , enables pollution problems elsewhere . my guess is that even though government have bought back franchises , sooner or later someone will ask the question , if the thinking on railways hasnt been wrong for over a decade .
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    Ok been mulling a few aspects of the Hydrogen position around and as follows

    1: water is plentiful and a source of hydrogen and oxygen if electrolysed

    2 Siemens Silyser300 unit marketing has published some figures using the PEM technology approximately 18.8 kg of hydrogen (and 75.2 kg of O2) is produced when 1000kw (1 megawatt) of electrical energy is used 

    3 if a car uses 2.5 kg of hydrogen per week this is 130kw for approx 200km of travel , yet an electric car uses 39kw per 100km or around 90kw for the same 200km journey ,in other words the electric vehicle will travel 40% more km per unit of kw than a hydrogen vehicle.

    4 Using Siemens Silyser 300 (at 75% cell efficiency) to make 188,000kg of Hydrogen would require 10,000 MW  

    5 the uk uses 700,000 kg of hydrogen per year (50,000,000,000kg globally) in chemicals industry ,only 4% of which comes from water electrolysis the rest is from hydrocarbons inc 45% from steam reforming of methane (so to meet the uks hydrogen requirement using water electrolysis would require 40000MW of electrically energy annually .


    My only question is why was the government promoting Hydrogen as a 20% natural gas substitute from water electrolysis , UK gas use is 72,000,000,000 m3 so a 20% by volume is 14,800,000,000 m3 of hydrogen or 1,239,530,988 kg of hydrogen ....?, I mean these are very clever people arnt they ???
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    Unfortunately if you actually look at any of the numbers behind the various 'green renewable' proposals they don't work. Electrifying transport requires a nuclear power plant or two. As you note just taking 20% of the UKs heating load will require some more. 

    I have read but not yet done the sums that 'carbon neutral' by 2050 will require at least one nuclear plant  to be built every week worldwide. Wind and solar using batteries or hydrogen as a storage or transfer medium don't come anywhere near meeting the demand.


    'Without the Hot Air' is still a good read:

    https://www.withouthotair.com/download.html
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    Hi Rodger , I really dont know where a lot of this carbon zero stuff is coming from, some really wierd projects have recieved government funding , which to anyone with even a basic understanding of whats green and what isnt , have gone through .Discussions are on for new nuclear plant as well . Carbon neutral is possible but it will take at least to 2050 , the other thing you never hear is about proper carbon sinks .or how they are going to clean water , really makes me cross some days how much money is being wasted ?

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