I am in South America at the moment. Met the Prime Minister of Guyana and the Vice President. I’m doing a project on sustainable development – the energy basis.
Right now there is an Exxon ship heading for Guyana to start making them wealthy. It is on the front page of the newspapers every day. Go get trained and you might get a job on the platform the Americans are bringing. The president says they aren’t going to make the same mistakes as Venezuela, Ecuador, Mexico, Nigeria. They are going to use the oil wealth (they don’t seem to realise Exxon’s purpose is not to make Guyana wealthy) for a green economy. They are not going to lay waste to their forests like Brazil (and New Zealand, and USA, and Tasmania) has done.
Oil in the ground is an actual fact. It is hydrocarbon molecules that can be separated and refined into highly combustible fuel (say diesel) that releases 45-48 MJ/kg at atmospheric pressure (36 MJ/lit). In order to have that fuel - 104 tonnes of crude oil will have to be extracted from geologic strata off shore in order to deliver 80 tonnes of high quality fuel (petrol, diesel, jet fuel) and 20 tonnes petrochemicals to the economy. This is because it takes 4 tonnes of oil energy equivalent input to discover, extract, transport and refine crude oil into 80 tons of fuel products. Guyana, like New Zealand, doesn’t actually use the sweet crude they produce, it is destined for other countries. Guyana will continue to buy the bottom of the barrel high sulphur bunker oil to chuck into their big diesel power plants to supply their grid, and they will pay the world price to import petrol for their cars. They may well decide to use that electricity and vehicle fuel to “build a green economy” and I am trying to help them with that. But probably they will just burn it, pay for it at a great deficit from what they earn on the oil, and best case scenario not go into debt too much because of all the wealth. What should they do if they have some money coming in from oil (like NZ does)? Their roads are terrible, their water system limps along, their waste management system is a mess, the city is dirty and chaotic and has open sewers. Mines are leaking cyanide into the rivers, Brazilians are running cocaine through and laundering money. The Vice President said, “Let’s look 100 years from now when the oil is long gone.” That is an excellent idea, and is one of the analytical steps in the new field of Transition Engineering my PhD student and I are using to do this research on transition to a sustainability future through regeneration of technical capacity, biocapacity and social capacity.
Think about the amazing challenge – what would you do right now to build a green economy? Good on Guyana. At least saying the words give purpose to the thinking and ideas that the people may come up with. Hopefully they don’t look to the Americans for the economics to use.
With all the challenges, and the fact that the oil should not be coming out of the ground at all right now – maybe 75 years from now. At least the people of Guyana and their leaders are not so dumb as to be talking about hydrogen.
That is what I have to say about that.
OK that is a really kick-ass article right there, but I’m going to go on and explain why hydrogen is a really dumb thing for a government to be saying is part of their vision for a national strategy.
Diatomic hydrogen (H2) does not exist except in the sun, or as a short-lived part of catalytic processing such as crude oil cracking or methanol reformation. Thus, it is not a resource. Hydrogen is a manufactured product with energy density at atmospheric pressure of 120 MJ/kg (or 0.012 MJ/lit). It is not anything like extracting and refining a barrel of free energy in the form of crude oil into 0.8 barrels of transport liquid fuels, 0.15 barrels of petrochemicals, and 0.05 barrels of bitumen. In the hydrogen economy, you start with the kg of fuel product (say diesel) you have already got which is not free and which you could use to drive a vehicle without building a new vehicle. You need to generate superheated steam at over 800C which is about twice the temperature as a steam power plant which is very high pressure so needs expensive equipment and you need to use catalysts that can survive this temperature to make it work – and the by product is CO (a poisonous gas). So if you were going to burn diesel to produce that type of steam (4 MJ/kg x 5 for reforming), you could generate power through a steam power plant or directly through a diesel engine, then you would have electricity to use. But our story is that we want a green fuel for vehicles?
It isn’t really clear at this point how to separate the H2 from the other reforming products of excess steam, CO and CO2, but it would definitely require cooling energy to condense the steam and bring the H2 back to room temperature to begin compression for storage in a tank.
Then of course is the compression energy to take the H2 to 700 bar is about 25 MJ/kg.
The embedded energy in the plant to reform and compress diesel into H2 isn’t exactly known because these reformers and compressors are rather specialist or research scale (e.g. don’t exist for the hydrogen economy) but let’s estimate given the types of materials that they are like the Methanex plant, then we get about 2 MJ/kg of H2.
So the energetic profit so far, from what is considered the “most promising route” for getting hydrogen into filling stations for vehicles is:
To Produce 0.07 kg H2 8.4 MJ
Invest 1 kg of Diesel (-45 MJ)
Invest 5 kg superheated steam (-20 MJ)
Invest 25 MJ/kg H2 for compression. (-1.75 MJ)
Invest in cooling and separation (not counted in the calculation but probably at least -10 MJ/kg)
So whereas in the Diesel Fuel System, the investment of 4 MJ of energy returned 80 MJ of fuel (EROI = 80/4 = 20) and some useful other products…
In the Hydrogen Fuel System, the investment of 66.75 MJ of energy returned 8.4 MJ of fuel (EROI = 8.4/66.75 = 0.126) and some toxic by-product CO and as much GHG CO2 after the CO is hopefully combusted as diesel fuel system PLUS the GHG CO2 emissions from the energy input.
EROI is the easiest way to burst the hydrogen bubble.
but what about green hydrogen?
If you have an idea that GREEN Hydrogen generated from "extra" renewable electricity could work. Then let's do the EROI on that.
First, let's be clear, there is no "unused" or "extra" electricity - that isn't how power grids work. There is spare capacity, but that is designed in for reliability. The grid is using the spare capacity for spinning reserve, for meeting peak loads, and to take up the loads if power plants trip out or are out for maintenance.
We all agree that the BEST energy engineering of solar PV is direct load reduction. This means installing the PV directly on the flat, unobstructed roof of a commercial, educational or industrial facility with large mid day loads that could be partly supplied by the solar. No solar PV goes back into the grid. The grid does not get strained it gets peak demand relief which directly reduces peak capacity margin. Good Good. Thus, if we do our jobs right, and policy incentives don't result in sub-optimal outcomes, then we would not have any "extra" solar PV.
Wind is the renewable resource that is like a bad boyfriend. It randomly gets excited and puts it in whether you want it or not.
Wind definitely has some periods of generation when the demand is already met by other assets in the grid. You can tell how often this happens by looking at the node price data for wind - when the price falls to zero or near zero then probably the wind generation will be spilled. So we don't really know how much wind could be available for electrolysis. What we do know is the electrolysis really should be a steady operation, not intermittent. That is a spanner in the works of the whole story of "when there is extra wind energy..." But let's not let technical feasibility stop us from calculating the EROI.
Wind EROI is about 20. Electrolysis energetic efficiency from electricity to H2 at atmospheric pressure is about 70%. So 1kg of H2 requires 200 MJ of electricity. To produce the 200 MJ of wind energy we have to invest 10 MJ in wind turbines. And we definitely have to compress the H2 to 700 bar at 25 MJ/kg.
To generate 1 kg of H2. 120 MJ
Invest Wind Energy. (-200 MJ)
Invest Wind Production (-10 MJ)
Invest Compression. (-25 MJ)
And the EROI = 120/235 = 0.51 That's a Deal Breaker! Recall EROI must be greater than 10 for it to be an Energy Supply System of Merit
So Green Hydrogen is obviously not an energy production system it is an energy consumption system. The CO2 emissions in this system are from the wind farm construction and compression, so yes much lower than the diesel reforming. But the whole thing is not a energy supply technology that can support any kind of an economy. It is a Biophysical Economics Fail.
But if we were going to build the wind turbines anyway, isn't it better to store the extra energy and use it later than to just waste it?
The engineering answer is "No". We don't run the wind turbine when the windspeed is below the cut-in because operating hours are not free, each rotation of the wind turbine incurs maintenance and expends lifetime. So come on - Renewable energy is not free. Think like engineers.