This was meant to be part of a longer article around the gas+oil decision, which will come out in a few days. It seems topical now so I thought I’d do it first.
Note: if you came here from the Carbon Sketches animation not the discussion seems to have moved a bit from exporting green hydrogen to using CCS to make it. CCS, like time travel, is a sweet tech that you should avoid investing in if you see it on eBay.
EVs only get you so far: large quantities of mined lithium go into making batteries that take time to charge and provide limited amounts of power. A used Leaf today might take you 80 km before needing a half hour top-up. While batteries are now appearing in large ships and even commercial aircraft, the same problem applies; short range, slow refill. The problem is known as specific density: effectively the power to weight ratio of a fuel.
An EV battery has a relatively low specific density (0.875 MJ/kg). Partly this is compensated through efficient use: in battery cars around 85% of the energy used turns the wheels. In a petrol car it’s closer to 15%). With this kind of density, they can’t compete with kerosine (42.8 MJ/kg) for long-haul flight or diesel (48 MJ/kg) in shipping: you would need to carry too many batteries for it to work.
With a specific density of 142 MJ/kg, liquid hydrogen can solve this. It’s also perfect in other ways: you can adapt existing internal combustion engines to burn it like a liquid fuel, or you can pass it through a fuel cell which creates electricity directly, much like a battery. You make it from water, and when you use it for energy, it combines with oxygen to produce water.
When I asked climate scientist and theoretical physicist Dr Shaun Hendy for his one genii-in-bottle wish to solve climate change his reply was ‘an efficient way to split water with light’: this is hydrogen storage in a nutshell.
So why do we use battery cars at all? In 1997 Wired Magazine predicted a future filled with hydrogen vehicles. Since then the specific density of batteries quadrupled, making EVs more feasible.
Hydrogen presents issues of its own. Creating liquid hydrogen wastes energy (in the form of heat), giving it only one third the efficiency of a battery. So while hydrogen solves the density issue, it costs extra to do so. The other problems are around storage and distribution. The EV’s main advantage is that it’s power network is already with us, and is so pervasive that until you actually drive onto the forecourt, your car is always closer to a three pin socket than a petrol pump.
Shipping and flight are the great unsolved problems in low carbon transport. For now, liquid hydrogen appears to be one of the best available solutions. Once hydrogen fuel is distributed to bulk transport nodes, it makes sense that it might also be used other forms, such as trucking. Again, it’s not simple to store, but the economies of scale help.
Here’s the problem with Taranaki’s plans for Hydrogen. For now, most Hydrogen fuel is created by burning gas. This releases carbon the usual way, and there is nothing remotely green about it. If you were to use gas as a ‘transition’, where infrastructure was created for generating and distributing hydrogen fuel, it might be used cleanly later on if the gas-powered part was replaced with clean electricity. At that point you’re essentially bottling sunlight for export; from a small, remote island nation with less free space for windmills than most, and losing energy over distance. It makes no sense at all.
The only way this can possibly work is by trapping the problem as it burns, much like a cigarette filter. These technologies (CCS) then force the CO2 back underground, often into old wells, where some of it can be re-absorbed. Cigarette filters, it turns out, didn’t really save lives and created more problems than they solved. Remembering that the PR companies working hard to promote them in the 50s and 60s are the same employed by oil companies now, we need to treat CCS with caution.
Unless it’s proponents can categorically prove that ALL of the carbon is captured, and stays safely stored for thousands of years, it’s simply better not to start.
Since writing this I’ve looked into the CCS tech intended for use in Taranaki. The Allam cycle addresses half of the problem (capture) and claims to pull close to 100% of the Carbon from burned gas. That is impressive, and if it could do that for the right price, quantity and timeframes it might be an enormous benefit. It is still very new (one small prototype in action now) and the storage half of question is still not clear.
To the decision makers in Taranaki, the people that fought proven science for more than thirty years ought to consider that there are plenty of nations with deeper pockets and bigger energy problems that could be taking the lead on this. We have limited funds and money blown on a technology that might not work is wrong when when safe, proven solutions are ready to go. There is over 2000MW of consented wind generation in New Zealand for a start.
We’ve made this mistake before. Greater Wellington Regional Council threw millions of dollars at a new electric bus technology that failed here, effectively giving free R&D to a US company that went on to bigger things while we scrapped a zero carbon bus fleet that was proven over 68 years of service.
Call us when there is a real price on carbon, and when we can be confident that local government is willing and able to monitor emissons rigorously and charge for them. Lets talk about it then.