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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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    There are a lot of difficult questions out there and very few answers that can be backed up with real data.

    Conspiracy theories abound; The Climate Activists are sure there is a plot by the governments and the oil industry to hush up the  ‘FACTS’. The right wing are sure that all this climate stuff is a leftist, Marxist plot to take control of the world. Quite a few on both sides are making quite a lot of money by selling schemes that get government subsidies. Most wind and solar generation systems are harvesting subsidies as are biomass. Where do the subsidies come from? Answer, the consumer.

    I am in full agreement that we need to reduce our impact on the planet. The questions are how and how quickly. Reducing the population is the obvious but impractical way. If we try and look at how big the problem is and how rapidly we have to do something we rapidly get sucked into the world of climate modelling. This is where it starts to get dubious and has far too many unknowns. The effects of cloud cover were discussed in a recent E&T article, clouds can make things hotter and colder.
    If you look back in history there was concern about global cooling in the 1970s followed by a fairly rapid temperature rise of around 1°C. This unexplained rise kicked off the current climate change movement/panic. Subsequently temperatures have remained fairly stable as the IPCC noted in AR5 (I am waiting to see how they deal with this in AR6 next year). Global CO2 levels have been rising fairly steadily during this time so It is very hard to make a sensible correlation. If the CO2 levels are not coupled to temperature then why should we do anything at all? If they are coupled then what is the sensitivity (temperature rise for a doubling of CO2 level in the atmosphere)? If the temperature continues to rise what is a safe limit? How do we know and justify that? Various proxy temperature measurements suggest that the earth has been warmer and cooler in the past and has survived. There are a wide range of temperatures across the planet that seem to be capable of supporting life. How do we even measure ‘Global Temperature’? Do we take a series of measurements on a grid around the globe and take an average? Do we take measurements where we can, apply weightings and take an average? How are the weightings justified?.

    A couple of charts from the UK Met office:

    https://www.metoffice.gov.uk/hadobs/hadcrut4/diagnostics.html

    Hadcrt4 is a global measurement which is also split into northern and southern hemispheres here to show the difference, note they have changed the scales the anomaly in the north is twice that of the south (why is there a such a difference?).

    https://www.metoffice.gov.uk/hadobs/hadcet/

    Hadcet is the longest measured temperature series based on three stations in central England. This shows the clear 1°C rise in the 80s followed by flattening as well as a bigger, ~1.5°C, rise in the 1700s. Who noticed that?

    Once we have got some justifiable answers to the above what do we do about it? Is the problem ‘Greenhouse gasses’ or is the problem all the toxic pollution load, over use of resources and destruction of natural habitats. Unfortunately a large amount of the green movement is fixated on greenhouse gasses and ignores the rest as it conflicts with their views/aims. All the renewable solutions solar, wind, biomass and hydro are not very green. They require large amounts of resources to build often using materials where significant pollution is produced (rare earths, cobalt, etc) and due to their low energy density destroy quite large areas of natural habitat. Let’s flood the valleys for hydro power, cover the hills with wind turbines and solar panels, chop down the trees for biomass and try and live and feed ourselves from the rest. I know this is a little exaggerated but do the sums to see how much are you need due to the low energy density of these sources.

    So what should we do? First try not to do more damage. The indiscriminate rollout of wind and solar is simply wasteful. Both do have their places but solar PV north of Spain is pointless as is placing wind turbines too close together so they shield each other. If you burn fossil fuels to manufacture wind and solar you actually make things worse in the short to medium term. Don’t shut down/scrap things before they have reached the end of their useful lives. Replace your transport system with an electric one when the existing one wears out. Nuclear with breeding and reprocessing is probably the best primary energy source available to us. It does need to move along from the older designs which were optimised for weapons grade plutonium manufacture to more flexible systems with much higher fuel burnup. The small modular reactors look interesting as do the various new physics although there is a lot of materials technology problems to be dealt with. The spent nuclear fuel is a small but rather unpleasant problem that can be largely be dealt with by reprocessing. Another important point is reduction in demand, but again don’t scrap usable housing and machines replace them with better when they wear out. Can we do this by 2030/5, no. Can we do this by 2050, probably not. Can we do this by 2100, probably. Is that too late, probably not.

    Just my ramblings

    Roger

  • 0 

    "solar PV north of Spain is pointless"


    Why do people keep trotting out these statements?  I have solar panels on my roof, and a small battery in the loft.  I have also been working at home since March, which means a computer on all day, as well as everything that I would normally have on in the evenings.


    Despite that, my average grid electricity usage throughout the spring and summer was rather less than 1kWh per day.  I was really close to being self-sufficient, and I will have exported more than I imported.


    It's now November, but the sun's come out.  That means the battery is charging, ready to keep me going for some or all of this evening.


  • 0
    Unfortunately your subsidised parasitic system is not indicative of the real world. What is your pay back on investment without subsidies? Do you have any idea what the energy return on energy invested is?
    Solar PV typically has a EROEI in low single figures in high insolation regions. If the insolation level drops in higher latitudes the EROEI can be around 1 which means you have just wasted raw materials.

  • 0
    Hi Rodger LOL greatly enjoyed your ramblings , ,your right about the mixed picture , and some places will have to make better use of what renewables they have 

    thanks Helios
  • 0
    Hi Simon , mmm the solar pv north of spain is pointless is an interesting point because even though they do well for 6 months of sunny weather , they do little and most roofs would have to draw offgrid in winter , 80% output on a cloudy day and still not very recyclable , however new based solar PV could tip things for anyone with a southfacing roof if they have heat efficient home , probebly wont be able to charge the EV though

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