How to Promote the Hydrogen Economy Hoax

Electric motors are very efficient - 92-94% is pretty typical. Gears are also quite efficient - about 98%, I think? Similarly, control electronics are very low loss.

If you are truly worried about efficiency, then how can you support hydrogen as a energy storage medium? Hydrogen returns less and 20% of the energy - over an 80% loss.

 

Your figures are actually ludicrously over-optimistic. It's not worth going through the detail though because even if they were 100% efficient the idea of digging a shaft half a kilometre deep and keeping it dry in order to store only a sunny afternoon's output from one solar roof like yours is laughable. It's probably better to use a powerwall!

One worries about efficiency when it makes sense to do so. Sometimes it is important - like when you are trying to run your car from a battery which is severely restricted in capacity and takes ages to recharge. You have to make use of every Joule to get a reasonable range.

An ICE car is highly inefficient, but this worries nobody because you can afford to carry vastly more energy than is needed. You can afford to chuck more than half away in waste heat and it will still take you 500 miles or more. And recharging takes a couple of minutes, so is not going to stop you for long. Were petrol (gasoline) to suddenly cost $300 a litre, then efficiency WOULD become important in the interest of saving money.

If someone can pay - say - $10,000 and never pay for fuel ever again he is not likely to worry too much about the efficiency of the system, is he.

In my case I support hydrogen because it involves less hassle than batteries. I do not want to have to fiddle about with wires and plugs and look for charging points etc. You are evidently happy with this which is fine, but I want to spend a few minutes every ten days or so which suits me better. Convenience trumps efficiency for me.

 

You are definitely a troll. The numbers I mentioned are widely known, and checkable.

Hydrogen fuel cell vehicles are dead on arrival.

FCEV are electric cars - they have electric motors, and batteries. The only difference is how they store energy. BEV's have a larger battery, and FCEV's have a small battery and hydrogen storage and a fuel cell to generate electricity to charge the battery.

Fuel cells are much lower efficiency (about 50%, I think) and they require a lot of cooling, because they do not tolerate higher temperatures. This adds aerodynamic drag - about 10% of the total drag comes from cooling. So, FCEV's use about TWICE AS MUCH ENERGY per mile, compared to battery electric cars.

Fuel cells wear out - they last something like 75,000 miles.

The Mirai has two compressors onboard - they make a fair bit of noise.

Protecting the high pressure hydrogen tanks in a crash, requires very strong structure; and if it fails, then hydrogen is extremely unstable, and probably will explode.

Hydrogen is expensive - it costs about $10-12 per kilogram, which is approximately the energy equivalent of a gallon of gas.

If you are willing to wait up to 200 years for all the filling stations to be built - then hydrogen is for you!

 

Are you seriously suggesting that a half kilometre deep shaft, a thirty ton weight, and an electric winch which stores a trifling 41kW - with 100% efficient motors and gears and everything else is a practical proposition? You can store the same amount of electrical energy in a battery the size of a small suitcase!

And the Mirai is showing more life than two-thirds of the plug-ins listed each month. I'd say reports of its death have been greatly exaggerated, wouldn't you?

 

You don't know what you are talking about.

https://www.gravitricity.com/

The total storage of each unit is 5-8MWh - not 41kW (sic)

The system is 80-90% efficient, which is what I said.

The system is scalable - add more units, and get more storage.

 

My calculations are correct. If each unit stores 5-8 MW they are a LOT bigger than a 30 ton weight! I think someone is bullshitting you!

Why don't we work out how big the weights are and how far they have to fall to store that amount of power?
8MW = 8,000,000 x 3600 = 28,800,000,000 Joules. So we have
m x g x h = 28,800,000,000. Divide both sides by g = 10, and we have
m x h = 2,880,000,000. If m is 1000 tonnes then m= 1,000,000 kg, so the pit depth (h) is 2,880 metres - nearly three kilometres deep.

Let's have a guess as to what a 1,000 tonne concrete block is like.

Concrete has a density of around 2.2 Tonnes a cubic metre, so a 1000 tonne block is going to be over 450 cubic metres. Think of an 8 metre cube, or a cylindrical block 6 metres in diameter and 16 metres long.

So nearly three kilometres is too deep to dig? Lets make it 288 metres. Now you have a 10,000 tonne weight. You could make a cylindrical weight 10 metres across and 58 metres long, but your shaft would have to be a bit wider than 10 metres - lets say 12 metres. And of course you'd have to make the shaft deeper by 58 metres to get the weight moving over the full 288 metres. Sound like a horrifically expensive and difficult civil engineering project to me.

You still have the problem of pumping water out of it, too. Deep mines always need to be pumped to keep them dry and that will take a significant portion of the energy you are storing, and reduce the overall efficiency. I doubt if this is included in the claim of 80-90%. Don't underestimate the need to pump water out. It was the need to do this that resulted in the development of steam power which started the industrial revolution and remember a wel is little more than a deep hole in the ground.

If you think this is a practical proposition then, by all means, invest in it, but I reckon its got SCAM written over it in six foot high neon letters. I suggest you do some simple calculations yourself before you part with a penny.

Personally, I much prefer the pumped heat storage system which could store 8MW in a building small enough not to be noticed in an industrial area. You could even put the two tanks underground without having to dig down more than a few metres. In rocky ground, I guess this could be crushed to provide the gravel where the heat is stored! Not a very big installation at all.

 

Projected vehicle mix:

Source: http://www.cargroup.org/wp-content/uploads/2018/02/The-Great-Divide-What-Consumers-Are-Buying-vs-The-Investments-Automake....pdf

I have my doubts about the "MHEV".

Bob Wilson

 

Martin, you need to sharpen your reading skills.

The weight is up to 3,000 tons.

 

Now you are obstinate, of course I know of one, actually I know of more than one but this is an example.


Or if you ar connected to the gas grid you can do methane reformation at your home. Or you can make biogas - 2 cows will power your Mirai for a whole year.

Is your BEV parked at home when the sun is shining the strongest so you can charge it for free? Can you be sure to find an other customer for the solar electricity that should have gone into your car battery in case parked at home but now can't?

 

Um, you don't have to charge while the sun is shining. You get full credit for all the electricity your solar panels generate.

 

The graph is palpably wrong. There are about three quarters of a million plug-ins on USA roads. With an estimated 260 million cars in total, that constitutes about 0.3%

As near as I can make out, the graph is claiming about 7% are electric.

'Nuff said!

 

We can all sit back and theorise, inventing clever ideas. When you dig into the detail, however, it becomes apparent that there are problems which are so expensive to surmount that one realises they are not as good as you first think. Here's one I had many years back. I'm pretty sure I am not the only one to whom it has occurred.

You sink a pipe from the shore into the deepest part of the ocean which is close to Mindanao I think. You pump fresh water down this pipe (it will be hard work because salt water is more dense than fresh water and you will need to supply it at up to about (from memory) about 20 atmospheres. When it is full of fresh water you put a reverse Osmosis filter over the bottom end and disconnect the pump. Fresh water pours out of the top of the pipe at about 5 atmospheres pressure (again from memory) and continues to do so forever. Not only is it desalinated seawater - i.e. fresh water - but it comes out at some pressure so you can extract energy from it! The reason is the differential pressure at the bottom of the fresh water column exceeds what is needed to filter fresh from salt water.

Perpetual motion right? And that's impossible! So where does the energy come from? Originally from the moon and the sun. They cause tides and wind and these together mix the seawater so that the concentration of salt remains substantially constant with depth. Were there to be no currents, you would find the salt concentration at the bottom of the sea to be much greater than that at the top. The pressure needed for reverse osmosis is linearly related to the salt concentration and the system would not work. So it is NOT perpetual motion but takes advantage of the potential energy available in the sea.

In theory this is perfectly sound, and should work. However, There are so many problems associated with engineering it that it simply isn't worth attempting. I submit it, only, as another example of an initially plausible idea that fails the test of practicality and financial viability which you may find amusing. Not to be taken too seriously! Were I a rogue, though, I am pretty sure I could sell it to a technically naive joker like Llewellyn who is too stupid or obsessed to work our where the problems are, let alone solve them!

 

Found a possibly appropriate use for a hydrogen powered vehicle:
http://www.businessinsider.com/how-vulcan-rocket-works-united-launch-alliance-2018-2#thats-less-than-spacexs-falcon-heavy-which-can-lift-more-than-70-tons-nearly-five-school-buses-for-one-fourth-the-price-but-bruno-said-there-are-big-differences-between-the-two-systems-that-will-make-vulcan-competitive-4

. . .
Vulcan's upper stage will use cryogenic oxygen and hydrogen, which are more resilient to the punishing temperatures of space.

ULA is also evolving its upper-stage system into what it calls ACES: the Advanced Cryogenic Evolved Stage. After deploying a spacecraft, ACES can be left in orbit for months or years and be refueled instead of being discarded as "dead flying hulks in space," Bruno said.
. . .
​

Sure, this will work .

Bob Wilson

 

Don't forget they have to use a quantity of oxygen, typically liquified.

Actually I was amused the article claimed to compete with SpaceX by having an orbiting hydrogen-oxygen rocket stage. Some of the other claims in the article were even more amusing.

Source: https://www.makai.com/ocean-thermal-energy-conversion/

Experimental power generation works but the pipes were damaged in an earthquake. The floating unit will reduce one risk but add a storm risk.


Given a choice between "n" hydrogen fueled vehicles and "4n" battery powered cars, guess which one wins. Point of reference, 100 KW would be 400 miles of battery EV every hour versus 100 miles of fuel cell powered miles.

Bob Wilson