Vodafone adopts hydrogen fuel cells to dodge African outages Vodafone in South Africa plans to avoid the recent problems it has had with South African power outages with more hydrogen-powered fuel cell base stations. To support remote mobile cell sites, Vodafone puts in on-site generation and microwave backhaul. The sites can be dedicated to 2G, 3G, 4G or use multiple technologies. …
I doubt they would blow themselves up. Hydrogen is stored under such pressure and so light that if someone did try it, I imagine the most that would happen would be the back of the drill hitting them in the forehead at high speed. Even if ignited, you'd get a fast, narrow jet of flame going straight up which wouldn't last long. Admittedly, it [b]would[/b] be invisible.
Still, the point stands - stealing hydrogen would be a lot harder than diesel or even natural gas. The only feasible way for a small time operation to do it is to steal the whole tank. Which is much easier to secure and, until Hydrogen becomes a common standard, would still leave you with the problem of what to hook the tank up to even if they did.
"Even if ignited, you'd get a fast, narrow jet of flame going straight up which wouldn't last long."
In the days when it was allowed - a school chemistry demonstration was a Golden Syrup tin filled with coal-gas. A small hole in the lid permitted gas to escape - and produced a nice flame when lit.
When the burn neared the end the remaining gas reached the critical mix which caused a small explosion. This resulted in a loud bang with the tin lid being propelled high into the air - having safely released the force of the explosion.
Not sure how that scales for a large sealed container of hydrogen at that critical point.
>>"Not sure how that scales for a large sealed container of hydrogen at that critical point."
It doesn't translate because hydrogen is so much lighter than coal vapour. The narrow upwards jet of hydrogen isn't purely the result of being stored at pressure as in your example, it simply shoots upwards regardless. It's one of the mitigating factors to hydrogen's flammability. So for example petrol vapours will pool around if there's a leak, being so heavy compared to air, whereas hydrogen, despite in theory being more dangerous, will be heading skyward the first chance it gets.
Hell, it's hard enough to keep in one place deliberately, let alone by accident. Not that hydrogen can't be dangerous, it can, but it's not usually this bomb waiting to happen that people seem to think.
Nice experiment for teaching chemistry to kids, though. Will remember that. :)
"Nice experiment for teaching chemistry to kids, though."
A more spectacular one in Year 8 was for the teacher to fill a large bottle with a mixture which may have been coal gas and air (or hydrogen and oxygen - it's a long time ago). This was then stoppered and wrapped in a lab coat. The class was dispersed to stand along a wall and the blinds were drawn to make it semi-dark. The bottle was then laid on its side at one end of the lab. The stopper was removed and a lit taper presented to the mouth of the bottle. The flame went the length of the lab.
On another occasion the experiment was to demonstrate a violent exothermic reaction with chemicals that were considered relatively unreactive. The class trooped outside where the requisite chemicals were made into a pile - with a magnesium strip protruding from the top for a fuse.
It was a windy day so the class formed a close circle round the pile to stop the teacher's match blowing out. Every time he brought the flame to the fuse the boys' circle skittered away and the match failed. Eventually the boys were persuaded not to move until after the fuse caught - and were treated to an erupting volcano with sparks and smoke. The caretaker probably wasn't too happy with the scorch mark on the lawn.
"
Not sure how that scales for a large sealed container of hydrogen at that critical point.
"
What you failed to learn when watching that demonstration was the need for a hole *in the bottom* of the tin as well as the top. The hydrogen initially fills the tin but is not under pressure. Being less dense than air, the hydrogen escapes out of the top hole while air enters at the bottom which creates the air/hydrogen mix that eventually reaches an explosive ratio (anything between about 10% and 90% will explode IIRC).
A compressed hydrogen cylinder with a hole in it would release hydrogen that would burn in air, but no air would enter. No air means that an explosive mix would not occur.
"What you failed to learn when watching that demonstration was the need for a hole *in the bottom* of the tin as well as the top."
Your explanation is correct. This section of someone's autobiography also describes the experiment. His brother then went on to repeat the experiment in a large drum with more destructive results.
https://books.google.co.uk/books?id=tSdYEni3rhoC&pg=PA71&lpg=PA71&dq=chemistry+golden+syrup+tin&source=bl&ots=DSXmIJlgZQ&sig=V8A9bMGH8qHJMUkkkDIlVUxNL08&hl=en&sa=X&ved=0CGcQ6AEwDmoVChMInrbhn7SQxwIVxyceCh0U8QAF#v=onepage&q=chemistry%20golden%20syrup%20tin&f=false
Makes me wonder what happens when a large container with a single hole no longer has enough pressure to maintain the jet of flame. Does the flame front retreat into the container and then allow air to enter until there is a critical mixture? Or can the flame front not retreat owing to the same effect used in the Davy miner's safety lamp?
I have a "Paddy Hopkirk" petrol can that is filled with aluminium mesh that supposedly prevents it exploding in a crash.
We used to do the same thing with an upturned duffle bag over one of the bench gas taps with a small hole in the bottom (now top!). Used to go skywards at quite a lick at the critical moment. Don't think the science teacher was too impressed though when he found out we were doing this in the lunch hour. Health and safety folk would have kittens if that was done these days. Come to think of it, I wonder what they would have made of our school Christmas revue shows, as there was a group of us who performed sketches each year that invariably involved explosions made with home-brewed flash powder from the chemistry lab. Oh, happy days.
"This part sounds like geenwash bollocks. Fossil fuels are the dominant source of industrial hydrogen."
Not to mention the need for some sort of vehicle to distribute the fuel cells, which would obviously need fuel itself.
Surely if they were being totally green, they'd have gone for Solar power? It's not as if South Africa lacks sunlight.
>>"Not to mention the need for some sort of vehicle to distribute the fuel cells, which would obviously need fuel itself. Surely if they were being totally green, they'd have gone for Solar power? It's not as if South Africa lacks sunlight."
Solar panels would have to be transported by vehicle as well, you know. Besides, hydrogen is only produced from fossil fuels because it's cheaper to do it that way - much like it's cheaper than batteries and wind power. The nice thing with hydrogen is that you can ALSO produce it cleanly if you wish. It's not a fuel SOURCE, it's an energy STORE. Whether you store energy from a clean source or otherwise, that's no different to whether you charged a battery from a clean source or not.
"Solar panels would have to be transported by vehicle as well, you know. "
?
Solar panels would be transported by vehicle twice during their lifetime of hopefully many years - once on installation, once on disposal.
Hydrogen refills are transported by vehicle on a weekly (or maybe monthly) basis depending on usage at the base station.
That said, I do quite like the fuel cell idea, seems to make a certain amount of sense.
You don't have to go all the way to Africa to find trouble with diesel or similar being nicked from tanks. Not a million miles from Vodafone HQ in Newbury, Berkshire, there are plenty of industrial estates etc where oil is used, where the oil has been known to disappear from time to time. Maybe elsewhere too.
"Solar panels would have to be transported by vehicle as well, you know. "
Yes, but only once. You need to keep sending fuel (whether it be hydrogen or diesel) to these remote places, most likely by vehicle of some sort. Yes, you will need to have someone come round and clean the panels, but that is less often than having to restock the fuel. Probably can be done as part of the general maintenance that is already being done on the installed equipment..
"The nice thing with hydrogen is that you can ALSO produce it cleanly if you wish. It's not a fuel SOURCE, it's an energy STORE."
Same thing applies to liquid fuel, with the bonus of being easier to store and transport. Liquid fuels like Alcohol, Petrol, Diesel, etc... are essentially hydrogen fuel with carbon atoms binding it. Hence the term "hydro-carbon" :)
Indeed the first combustion engines ran on renewable fuel. Early internal combustion engines ran on coal gas. Otto's 4-stroke was alcohol fuelled, while Diesels engine ran on veg oil. The only reason we use fossil fuels is because it is cheaper to dig it out the ground then it is to produce it cleanly.
I remember reading somewhere that the raw cost of refined petrol (minus all the taxes, and profits, etc...) would have to hit 95pence/L before it becomes viable to mass produce it(*) cleanly rather than dig it out. Currently the raw cost of pumping and refining oil into petrol is about 2-3pence/L.
(*) by "it" I mean a clean renewable fuel that can burn in petrol engines. It can be a 1-1 replacement like Butanol, or Alcohol fuel (which would need modifications to existing engines).
Sure, copper theft is a major issue in South Africa, but "load shedding" is the main issue for power outages that affect communications and businesses
The state owned electricity supplier ESKOM is in a world of shit, they are generating almost 40% less electricity than they were in 1994, when democracy came about
This is caused by under investment in the infrastructure, loss of expertise (as in replacing the predominantly white engineers with a workforce that is more representative of the population) and massive delays and billions in additional and non-budgeted costs on their new Medupi power station.
To counter the shortage of electricity on the national grid, ESKOM "schedule" load shedding, although this is mainly aimed at residential areas, it also causes businesses pain and inconvenience.
Home owners and SME/SMBs are relying heavily on solar/inverter/battery power and petrol/diesel systems to ensure they have power 24/7.
There is nothing more frustrating than not being able to get a phone signal, fill your car with fuel, or pay for your groceries at the local supermarket when the power is down for long periods.
This also effects the cellular networks, especially when towers are based in the residential and commercial areas that often suffer these long, 4 hour plus power outages
Kudos to Vodacom (as Vodafone is known in S.A.) for coming up with a solution, after all, phone and data services are key to homes and businesses and shouldn't be affected by theft or incompetence. It reassures subscribers that they can be in touch with friends, family and emergency services when power is out.
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