Superpants

In a production line they often come fitted with a plastic clip with a loop in that you pull off, similar to your nut concept. Not unsual to hear them called grenade clips. https://www.mubea.com/sites/default/files/styles/max_500/public/2019-05/06_raumspar_federbandschelle_mit_handy-clip.jpg?itok=0DAg2_-W

My surname has always got shortened to Pants since primary school. A conversation at uni ended up with me announcing 'Superpants to the rescue', ever since then it has been a nickname.

I've got the cheaper wurth one- had it about 6 months and so far so good!

I've now built three sheds where I have used fencing feather edge boards. They are fairly reasonably priced if bought from a specialist fencing supplier- The one I use is quoting £1.69 per board at 1.8m x 22mm x 125mm. With a 25mm overlap that comes out at less that £10/sqm. If you go this route I would recommend using a membrane behind it. This the latest shed project during the build

If it's thin a wad punch works pretty well- No snagging then!

My only royal story involves Land Rover products: About 15 years ago Mark and I were travelling down to South Wales to meet some of the forum members for an off-roading weekend. We were in Mark's Disco that he had at the time, with him driving as we headed down the M4. As we came close to the windsor junction we noticed two identical Range Rovers in the nearside lane in close successsion, as we slowly passed them I looked out the window casually and had to do a double take as I realised the women in the rear of one of these vehicles looking closely at us was the Queen. We joked at the time about what she was saying to the others in the car- maybe 'Oh look one's subjects are going orrffff roading" RIP Ma'am

Slighty more difficult would be to fill using solid rivets if you can get to both sides. These can then be filled flat and then painted- The way aircraft are put together (all though they may mill them flat).

Index marine do a range of glands for larger connectors- useful on boats for aerial connections etc- I used them on miltary vehicles in the past succesfully. Index marine

Watching this with interest- I've been contemplating options soledering myself. I had a job where I needed to de-solder a load of 2.5sqmm wire. My 15W Antex was way underpowered, and a cheapy 50W iron had a terrible tip that refused to tin. In the past I had an oppurtuniy to borrow a metcal from work whenever I needed a good iron, but no longer work at that company so not an option. The secondhand Weller stations seem overpriced for secondhand to me. Might well therefore try the atten one from Maplin unless you might have a metcal available @Ed Poore?

For the equivalency: 1kg approx. equivalent to 2.8kg petrol (approximately 1 gallon) https://afdc.energy.gov/fuels/hydrogen_basics.html

Good points- I'll have to look out the energy density equivalents. On the return to gas, you are right that getting it to a gas isn't the challenge, what I should have added there is that the gas would then need compressing to a level which it could be transferred to the vehicle- again adding complexity and another (energy efficiency) loss.

I've recently seen a couple of press releases that may be of interest. The first is a serious attempt at Lithium carbonate extraction in the UK, with a pilot plant running: https://britishlithium.co.uk/first-lithium-carbonate-produced/ It's worth noting that the vast bulk of Lithium ion batteries don't use metallic Lithium, and compounds such as carbonates may be used directly. Secondly Veolia, one of the biggest waste management/ recycling companies has announce the construction of a UK dismantling/ recycling plant: https://www.veolia.co.uk/press-releases/veolia-announces-its-first-electric-vehicle-battery-recycling-plant-uk

As I promised, I've finally written up my thoughts and observations on Hydrogen use as a fuel. Apologies it's taken ages to get round to this- Christmas kind of got in the way! As an opening point, Fuel Cell Electric Vehicles (FCEV)s are Battery Electric Vehicles with additional components, and a reduced sized battery pack. The battery is necessary to start the fuel cell stack and to take account of the short duration variations in power needed by a vehicle- a finite time exists to ramp up power from the fuel cell stack as it's output is related to the gas flow in, both H2 and air. In my opinion, Hydrogen is not a viable or sensible solution for personal transportation, or for many of the other areas where we currently use liquid fuels (petrol, diesel, fuel oils) or natural gas. There are use cases where it does make some sense, but I see these as only a very small proportion of the total. There is a good analogy of Hydrogen being touted as the 'Swiss Army Knife' of solutions. Much like the Swiss Army Knife it COULD be used as an energy carrier for lots of these tasks, but it probably SHOULDN'T for most of them as there is a better option available. See the link for an illustration; https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich/ There are a significant number of challenges which have to be overcome with Hydrogen; Efficiency & Green Hydrogen Many hydrogen proponents start the conversation with something along the lines of "IF we use excess electricity to hydrolyse water then the solution is green". Whilst this is true, the electrolysis of water is highly inefficient- Peak efficiency is around 50%, and due to the electrochemistry of the reaction can't get significantly better than this. The conversion efficiency in the fuel cell back to electricity is in the range of 40-60% if a Proton Exchange Membrane (PEM) cell is used (currently the only practical cell for automotive use). If we ignore all the other losses in managing and distributing the gas, the best efficiency from electricity in to useful power at the wheel is around 25%. Once the distribution and any other losses are included, the efficiency will be less than 20% If we compare this with an BEV- transmission and distribution losses will be less than 10% and the efficiency of charging batteries and then delivering power from battery, through inverter, motor and drivetrain to wheel will be around 90%, we will see an overall efficiency of around 80%. (Numbers are all approximate due to difficulty of pulling accurate figures together that compare directly- there are studies that attempt this though). If we use green hydrogen, and the only factor in play is commercial, this efficiency difference alone would be enough to stop FCEVs in their tracks as they would be some 4-5x the cost to run per mile than a BEV! With the exception of very limited uses where paying a premium for increased range (and/or reduced fuelling/ charging) would be justifiable, for example some military vehicles or agricultural vehicles, this cost difference would be prohibitive. Greenwashing Whilst we could generate Hydrogen from green electricity, more than 95% of current production comes from 'reforming' of methane, and so as of today, FCEVs are not green. Worse still, there is a strong lobby from the oil companies to keep using petrochemicals as feedstocks for hydrogen. Understandably they want to keep using their reserves as we reduce our dependence on other liquid fuels. Until recently this lobbying has been at a low level, but since COP26 it is becoming more visible. I have seen Youtube ads, and recently the Sunday Times magazine carried a double page advert from Aramco advocating hydrogen related to this campaign: https://www.aramco.com/en/campaigns/powered-by-how/blue-hydrogen I can't see a solution where the green hydrogen would be economically viable against Hydrogen from the oil companies (due to the inefficiencies discussed above), and they have a second advantage- that they already own a distribution network that could be transitioned to supply of Hydrogen. Thirdly there are unfair comparisons being made- if you compare Hydrogen against existing fuels (petrol/ diesel), as is commonly done, you get a very different picture to comparing against electricity Up until now, I have illustrated the best case scenario for green Hydrogen- i.e. made with excess green electricity. Unfortunately we are not in a position of having significant excess green electricity supplies, we currently use it all in offsetting our generation by other fuels. It will be another 20 or more years before we truly do have excess green electricity that we could seriously consider using for Hydrogen production (generalisation!- We may see limited scale peak levelling schemes in a shorter timescale- that would be a whole other discussion) https://gridwatch.co.uk/ There are also a number of technical challenges to also be addressed; Storage and distribution Storage of hydrogen and it's distribution is difficult. It can either be moved as a compressed gas, or as a liquid. Both have significant challenges. Hydrogen is a gas with a very low density, and so to compress it to usable levels requires a lot of energy, even when compressed heavily, it's density remains low. There are absorption methods that help increase the gas that can be stored in a cylinder, but even with implementing these we end up with sizeable storage tanks. If we look at commercial cylinders, a 50 litre nominal cylinder only holds 1kg of gas!!! https://specialty.airliquide.co.uk/product/hydrogen-5-0-501/?industry=oil-and-gas Whilst a lot can be done to reduce this mass, it nevertheless remains a significant part of the vehicle mass, less than batteries but not insignificant like a petrol tank. As a liquid, the fill density will be much higher, but then you have to maintain the temperature below -253C, put a lot of energy in to liquify, and live with constant losses with the gas boiling off (again detracting from efficiency). I'm not aware of any practical applications on vehicle using liquid fuel, so you would also have the complexity of converting from a liquid and back to gas at a fuelling station. Technical Complexity It's easy to think of just the fuel cell stack itself, which in reality is quite simple, but there is a lot of complexity around this; Water management is needed to both stop the membranes fully drying out as they warm up, but also remove the generated excess water safely (without causing isolation issues when running at 100s volts). Temperature needs control- freezing of the water would also be detrimental as would overheating. Air is needed in large volumes, so powerful external blowers are needed. This comes with air management and filtration needed to avoid bringing in dust or particulate contamination. A level of cell balancing and management is needed, similar to that used with Lithium ion cells. Pipework and valves are needed for the H2 gas supply. All of this needs careful control to balance the gas flow with the electrical load. There are now well integrated solutions to much of this, but there is a level of complexity to these systems that is often not thought about. Rare Metals Whilst fuel cells do not use rare earth metals, the PEM type used in vehicles do however use platinum, another metal where supply is limited and expensive. Life & poisoning As fuel cells are reacting two chemicals together with aid of a catalyst, there are mechanisms for the catalyst to be 'poisoned'. The presence of a number of chemicals particularly Sulphur containing ones, such as Hydrogen Sulphide and Sulphur Dioxide as well as Carbon Monoxide and Sodium Chloride can reduce the effectiveness of the cell significantly, reducing it's life. https://www.technology.matthey.com/article/57/4/259-271/ https://www.hydrogen.energy.gov/pdfs/progress05/vii_i_4_uribe.pdf This means the hydrogen used must be very pure, but even with this in place there is a very real risk of atmospheric pollutants making their way into the cell mixed in with the feed air, and subsequently shortened lifetimes. Other uses In my opinion, the best uses for any hydrogen generated from electricity in schemes using excess electricity is in displacing fossil derived hydrogen as chemical feedstocks in industrial processes such as the manufacture of fertilisers. Whilst there would still be an efficiency hit in the electrolyser, we don't get the second hit when converted back to electricity. Secondly these processes need hydrogen, there is no other viable alternative, and so eliminating the use of methane would bring additional benefits- no carbon capture needed for example. Much of what I have written has been summarised as a graphic known as the 'hydrogen ladder' which can be found at the first link above. This neatly ranks the uses of hydrogen from 'Unavoidable' there is a clear benefit (such as the chemical feedstocks above), down to where they are 'Uncompetitive'. Overall I think this is a well thought out and presented graphic, I'm sure there are some use that could change position a little, but I believe the overall ranking is sound.

Thanks everyone! Yup- I will be!!!! Having had the oppurtunity to work on such a wide range of vehicles and system types has exposed me to the real engineering challanges and hopefully that means I have been able to pick up useful information to share!