Contents Continued

By David Rhys-Jones

Hydrogen

One of the joys that the Covid Lockdown has denied us is the annual escape to the New Zealand Summer. The discomfort of 24 hours in a cattle class seat is amply rewarded by a couple of weeks floating round the Southern Alps Recently, the prolonged ache in the backside has been made worse by the pricking conscience that says this selfish act is releasing a huge amount of Carbon Dioxide into the atmosphere.


Having little else to do other than wheedle another mini bottle of Sauvignon Blanc out of the cabin staff, I turn to the literature in the seat pocket. I find that the Boeing 777 carries about 140 tonnes of kerosene and about 350 passengers. A quick calculation says that, if it fills up twice to get to NZ it will have consumed 560 tonnes on the round trip. This means that I have personally burned 1.6 tonnes of kerosene or about 2000 litres. This is far more than I put in the car each year. So much for my hybrid car and careful rubbish recycling.


My days of flying to New Zealand are now finite, but I certainly would not want to deny the pleasure to my children or their grandchildren. However, global warming cannot be ignored and involves everyone. The youth, at least understand that there problem, and it is to be hoped that the ignominious departure of Trump will draw a line under climate change denial. However, people have always wanted to fly and they always will. Mankind is inherently resourceful and will find a solution.  


There is a solution. It is hydrogen. Burn Hydrogen (H2) with Oxygen (O2) and it goes to H20 or water. However, a lesser known fact is that a tonne of liquid hydrogen contains three times as much energy as a tonne of kerosene. About 90% of Aeronautical Engineering is devoted to reducing the takeoff weight of an aircraft, so Hydrogen fuel is a no-brainer. Granted, there are a few technical problems but nothing compared with the problems that confronted the Wright Brothers or the men who developed the Spitfire or Napier Sabre in a few months of the Second World War.


Sadly however, the Aircraft Industry is no longer dominated by the engineering giants who brought aircraft to their present state of development. It is dominated by Accountants and Marketing men, talented in the art of disguising backhanders to politicians and airline executives. Who else would have allowed or even encouraged the fiasco of the 737Max, where a company tried to squeeze a few more years out of a 1960s aircraft.


How do you make it ?


Hydrogen can be made using fossil fuels, but this would defeat our purpose. As you probably learned at school, it can be made by passing a DC current through water and collecting Oxygen on one side and Hydrogen on the other.   Pure oxygen has a lot of uses and can be sold. Hydrogen can be liquefied and stored and it is the storage aspect which is attractive.


If you are not concerned about when you get it, electricity can be surprisingly cheap. Power demand fluctuates every time the population decides to brew a cup of tea. It is difficult and expensive to switch power stations on and off, and for much of the time the wind turbines off Worthing are generating power that nobody wants. If you say you will take that power, they will sell it to you very cheaply.


The hydrogen then it then needs to be liquefied. This is done by repeatedly compressing and cooling it until it finally liquefies at -253 degrees centigrade. This process takes a great deal of energy which is largely given off as heat when the gas is compressed. As the process only requires a power cable and a water supply, it can happen at the airport itself  where the surplus heat can be put to good use.