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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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    Sorry Joe looks like I replied to Simon in error, I think the new Mira is quoted at around 400miles for 5kg of hydrogen , and i they are investing heavily in Hydrogen infrastructure in Japan , and they have the temperature extremes , so the water retention button is a good thought , as potentially over 400miles i think 100kg of water would be made. Whilst the fuel cell (stack) can run at low pressures , every effort at the moment is being made for them to run at high pressures , as the Hydrogen is so light , that you need high volumes to react to get the higher output .Pressurising the Hydrogen tanks is quite debated also . It is a good article by Prof Wolf Vielstich and he perhaps couldnt see the SOFC cells , which I agree are quite interesting . to make 5kg of Hydrogen from water would take 60x5 = 300kw and then a further 12kw to liquify the 5kg , but the fuel cell itself is not as efficienct as the battery pack in the Tesla , which we know a battery is around 80-90% of the power in the battery is converted into KN , whereas the fuel cell (as its not a lab conditions fuel cell) is around 60% , hence the Tesla goes further per kw of energy as there are no conversion losses. However where you can make very cheap hydrogen in sufficient supply this may not matter , the fuel cell is more recyclable so may be cheaper , however if we do use fuel cells or exotic metals in batteries then we may get enviromental dmage due to mining , hence recyclability is very important .

    If they make the ideal battery (and I havent seen one for sale yet) then this could change , dont forget the car can use braking energy to recharge a battery , so the efficiency has yet to be applied .

    but thanks for post says on wikipedia 240ml for every 4km for the Mira , actually thinking about that figure i think makes water retention on sub zero conditions a compulsory extra to be fitted , a motorway with 100 cars on a 4km stretch would be recieving 25 litres of water every time unit , as fine coating or crystals.

    Helios
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    An excellent subject with lots of data.  But what is fantastic is that a UK Hydrogen-powered train made its maiden journey this week.  A hydrogen-powered train has travelled on Britain’s rail network for the first time. The prototype, called the Hydroflex, made a 25-mile round trip through Warwickshire and Worcestershire, reaching speeds of up to 50 mph. Its next phase is to move the hydrogen tanks, fuel cell and battery out of a carriage and stash them underneath the train. The aim is for the train to start carrying paying passengers by the end of 2021.


    We have also had the first test flight of an electric plane in the UK at Cranfield University, which was powered by a hydrogen cell.  What with hydrogen cars and boats it looks like the fuel of the future or maybe not.  Therefore, the East Midlands Event:

     




    Should be a very interesting topic to listen to and join in.

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    I suppose Hydrogen had to be tried in a railway vehicle and in the road vehicle and air transport , but for me the maths doesnt work too well for its future one well respected engineer has pointed out the relative efficiencies and it takes around 2.7 kw of energy to get 1kw of energy at the wheel with hydrogen , and unless you use water electrolysis each 1kg of hydrogen is 12kg of CO2 , so at the moment hydrogen isnt exactly clean and even if you do use water electrolysis , the energy required is eye watering. if you take the current PEM water electrolysis figure of 60kwh for 1kg of Hydrogen  1 million cars filling 5kg (400 miles every couple of weeks ) say every two weeks or 2.5kg every week is 2,500,000 kg every week at 60kwh is 150,000,000 kwh of new electricity requirement , and something like 27 million cars on the road its easy to see how things from electrical requirement start to cause problems. we also dont know the Hydrogen consumption of the train yet and as has been speculated it could be more efficient and cleaner  to use ethanol from bio digestion , if 50mph is the requirement . Still not for me to say the people who are promoting Hydrogen arnt getting the true energy conversions into engineering thinking.

    As for Ammonia as a fuel its quite interesting , only problem is it might smell a bit , and I quite liked it for shipping for a while , just have to wait and see what true emissions are , might be an alkaline exhaust as well , as for power its about 40% around 15000 kj/lt I think although cant find any combustion figures on it . Ammonia at the moment only uses fossil fuels or nuclear , so it has same problem of Hydrogen .
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    The big question is how hydrogen for trains compares with diesel.  I can't imagine a diesel-electric train is terribly efficient at converting the energy in the fuel into power at the wheels.  We still have many lines in the UK running on diesel, and I can't imagine them all being electrified any time soon.


    On the whole, I prefer batteries for vehicles, because of their efficiency.  But it would take a huge (expensive) pile of them to run a train for a day, and it may not be convenient to shedule regular half-hour recharging slots if the battery won't last a day.
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    Compared to an electric train powered by a fossil fuel power station diesel is quite good. An optimally loaded diesel engine has a high efficiency (40%?) and there are no losses from long distance transmission of the electricity. For long haul diesel electric is probably better than electric powered by fossil fuel power stations. For stop start where regerative braking can be used electric will probably be better.

    If you can get your electricity from hydro and nuclear Swiss style then electric is best.

    Unless a much more efficient hydrogen production method can be found it will remain worse than the alternatives. Hydrogen is just an energy transfer medium not an energy source.
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    mmm well its fair to say that diesel electric has arrived at relatively clean emissions , they use addtives or collect the dreaded particles and combust them , and the interest keeps rolling because of Diesels energy density , battery trains sound good , and if as a package on a line with no inclines ,perhaps have a specific use/fit , they are trying hybrids , but I think there is a problem with weight , as also with the hydrogen fuel cell.
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    Exactly , its when you start to think about the fit overall in emission terms , and the railways have some unique engineering considerations , to do with distance , that make reliability so important , at 500 tonnes for a typical modern 450 seat consist , the fundamental fact is you need power and Hydrogen just doesnt deliver that sort of power and even with electric systems you can run into power problems, which is why the dedicated passenger line seems attractive , but I think it will turn out we will be better off with a flexible rail network , and keeping freight on the lines to any point
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    Just seen a promo vid for BMW next generation fuel cell tech , which they will fit to larger car range in 2023 and the fuel cell will give 125kw but have a battery which seems to be around 110kw giving a potential short output of 235kw , so it will beat pure electric systems , carrying around 6kg of H2 as liquid should be good for 400-500 miles between fill ups which take less than 10 minutes . They dont give the wt of the system , which looks similar to the lion battery packs , but they do give the tank pressures at 700 bar (10000 psi in old money) , and water vapour exhaust straight to road . have to increase road tax to pay for all the lush vegetation growing by roadsides ?, darnt think about cold climates , freezing temps on a motorway ???.
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    An interesting article on hydrogen powered trucks which includes some numbers:

    https://www.swissinfo.ch/eng/switzerland-s-driving-role-in-the-green-hydrogen-revolution/46079974



    'A kilo of green hydrogen currently costs CHF10-CHF12 and lets a lorry cover about 11 kilometres. According to one study, this price should halve over the next decade'.


    'Hydrospider uses electricity produced by the hydroelectric plant in Gösgen, canton Solothurn, to break water down into hydrogen and oxygen (electrolysis). Its two-megawatt plant – the largest in Switzerland – can produce up to 300 tonnes of hydrogen a year, which could fuel around 50 lorries or 1,700 cars.'


     


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    Hi Roger , mmm well at least we have some figures , I think the current medium sized hydrogen car is around 1kg for 80 miles (130km) , so 1kg for 7 miles (11km) isnt too bad I assume it was carrying its full 44 tonne train weight , the figures that may be more difficult is on a hilly route fully loaded .Given a car hydrogen tank is a pretty large item then the HGV version , and fuel cell must be considerable , so be interesting to see some weight figures . CNG and LNG trucks have been now fully tested so they can work on most routes. The main problem for hydrogen operators will be filling if an typical hgv journey is 300 miles per driver (480 km)) then thats around 43kg of hydrogen which would be a massive tank , and 43 kg from a filling point is a big ammount to do , i think somthing like 2700 kwh of electricty would be required for just 43kg of hydrogen so swiss gren hydrogen could only fuel maybe 15 trucks per day ?

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