Long time lurker first time poster here on STT. I do like the STT forum as it seems a bit more...level headed than the DT forum and many of the company specific ones I follow.
I saw you guys talking about Hydrogen as a topic some time back and was going to post then but I have had a lotta stuff going on and missed the opportunity.
All in my own opinion - Bear in mind my work background is from Automotive - An auto electrician and refrigeration repairer to be specific. Hydrogen as a fuel is a novel idea - on a very surface level basis yes it is a cleaner fuel. Speaking very generally, conventional petrol powered ICE systems produce CO2, various Hydrocarbon compounds (HC), and Various Oxides of Nitrogen (NOx) during the combustion process. These are minimized by conventional emissions related controls such as Exhaust Gas Recirculation and the use of Reducing Catalytic Converters, as well as overall engine designs incorporating advanced engine management logic, in particular strict control of Ignition timing events, combined with mechanical design concepts such as Variable Valve Timing and Direct Injection.
When you have a Hydrogen ICE you don't have the HC or the CO2 to contend with, but still have to work with the NOx - which is complex to get on top of. Other emissions include Oxygen in its native form and water. The NOx is the problem. Nitrogen Oxide (N2O) has a greater global warming potential (GWP) than CO2 - Significantly higher - multiple sources I have state different values but going off my Australian Automotive Air Conditioning handbook it suggests >270 greater GWP than CO2. This is important as the overall Basket of NOx produced from burning Hydrogen as a fuel gas is greater than the Basket of NOx produced from Hydrocarbon fueled vehicles - leading to a more complex design of Reducing Catalytic Converters. The tech bulletins I have read (which are limited mind you, due to the lack of production line Hydrogen ICE cases), suggest that the NOx problem is the main design problem to be overcome here. Using one type of Catalyst system captures one form but ignores some others, and vise versa. Using additive control systems similar to the widely used Adblue system in place in some drivetrains have the same issue, they control one pollutant while creating another.
Moving on to Hydrogen Fuel Cells - this is where the future of Hydrogen fuel is, if it indeed has one IMO. I have often mused at the concept of the Electric Revolution and Net Zero 2030 and thought it was total fairytale stuff. Still think that. There is NO WAY that we can achieve that in that timeframe. The technology isn't there and the resources to pull it off aren't there either, not to mention the timeframe of building the infrastructure either. If you are using a Fuel Cell for power generation, the exhaust emissions from that are only O2 and water - but looking big picture - which is what so many people who are suckered into thinking Net Zero is possible fail to do - How does one get the advanced materials required to construct a Fuel Cell to start with, and how does one get the Hydrogen to fuel it?
Comes back to fossil fuels doesn't it. Ill bet you the raw materials required to construct that Fuel Cell were dug up by a diesel powered piece of machinery, transported to the processing plant by a piece of diesel powered machinery, fed into the processing plant by a diesel powered piece of machinery, processed in a plant powered by either a gas fired or coal fired power plant. At some point the materials make it to a Fuel Cell manufacturer, probably freighted there by a diesel powered piece of machinery, who then builds the Fuel Cell (most likely with the lights on, powered by a Gas fired or Coal fired power station), and encases it within a plastic compound of some sort casing - thank you very much fossil fuels.
Alternatively, the processing plant could in fact be powered by a humongous scale solar array - ok, the catalyst to produce the power from the sun for free, an ongoing nuclear reaction happening millions of kilometres away, that's great. The solar arrays were built from precious metals dug from the ground using a piece of diesel powered machinery, transported to a process plant by a diesel powered piece of machinery, and processed within the plant powered by a gas fired or coal fired power plant. They are then transported (most likely by the mighty fossil fuel powered machine), to another manufacturing plant, probably powered by fossil fuels...etc. You get the idea of what I am saying...
The simplified version of the First Law of thermodynamics states - energy cannot be created nor destroyed, but it can be changed from one form to another. Energy losses from change of state - in this case the store of potential chemical energy contained within the fossil fuels, changing into heat energy to produce steam to drive a turbine for electricity generation are inevitable. I mean, you're literally burning it there is a huge amount of wasted energy that becomes heat and other gasses. Then taking into account things like friction - Newtons Third law of Motion, the mechanical opposition of air vs the turbine, the bearings and shafts within, etc you have more losses. There is no such thing as a free lunch - all energy exchange is a tradeoff with some level of wasted energy.
So looking above, Fossil fuels are needed to supply the materials to build the fuel cells, beautiful. At some point you have to get the Hydrogen to feed the Fuel Cells too - where do we get Hydrogen from? And once we have it, how do we get it to the fuel cells?
Its not as simple as concentrating it from the air around us - our atmosphere is 78% Nitrogen, 21% Oxygen and 1% of everything else. Of that 1%, Native Hydrogen comprises 0.00006%. The proposed bulk production ideology is to split water to produce Hydrogen at scale...this is a problem as you would require the water to be clean from contaminate to begin with, ie freshwater, you're not going to drain the Dam in Sydney for example to make fuel for the power plant. The go to seems to be water reclaimed by desalination - which is a hugely energy intensive process on its own. Then split it - more energy to ultimately create two gas streams, which require more energy input to separate and contain. Once separated, it either needs to be piped from a plant to a power plant or bottled. Piping requires more energy to make the pipeline and create the force to move the gas and bottling requires energy to drive the refrigeration system to remove enough latent heat energy from the captured Hydrogen gas to allow it to condense into liquid form. Hydrogen boils at -253c, so at your ambient Australian Summertime temperature of 35-40c it will always be present in Gas form when uncompressed. Under compression it is possible to maintain Hydrogen in liquid form, however due to its extreme low boiling point, its incredibly difficult to maintain a significant quantity of gas under pressure and avoid migration of heat energy of the air surrounding the vessel into - that's the Second law of thermodynamics - Heat energy always migrates from a substance of higher temperature into one of lower temperature until equilibrium is attained. The migration of heat energy to the liquid hydrogen causes its temperature to rise, and change state, causing expansion. So two problems with storing bulk liquid hydrogen - the energy input to cool it enough to allow a change of state from Gas to Liquid, then keeping the heat energy out of it to avoid it changing state back to gas and expanding, potentially compromising the integrity of the storage vessel. The Cryogenic Refrigeration system used to achieve this is likely powered by...fossil fuels.
Don't get me wrong, it's a wonder fuel really, but until the renewables are built to power the energy intensive processes required to produce the stuff at scale we wont see any uptake on it, IMO. You gotta crawl before you can walk. And there is no way the green energy revolution will be even crawling before 2030.
My viewpoint is that in the future you might see it as a variation of our current hybrid drive vehicles - a Fuel Cell hybrid opposed to a Battery driven hybrid, but that will be a long way off unless there's some significant development on actually producing the stuff, and storing it easily/safely/inexpensively.
