There are even funky concepts around to capture the CO2 on board the ship (using a reformer - the hydrogen goes to a fuel cell) and bring it back to land for synthesis
while most studies consider Fischer-Tropsch for kerosene, methanol is also in the running!
methanol-to-kerosene is around 90% efficient, but not yet commercial
going via methanol has big benefit that methanol synthesis can be run more flexibly than FT (big advantage with VRE!)
even if we reduce, reuse, recycle, we still need some primary production of plastics, paints, adhesives etc.
methanol can serve as a flexible basis for many of these (many already used in China)
obvs we still will also need ammonia for fertilisers, etc.
methanol use today:
Yes, the synthesis of methanol adds losses to chain of conversion, but you also save e.g. the compression losses of transporting and storing gases like hydrogen.
If carbon comes from sustainable biogenic sources, cost can be 70-90 EUR/MWh
Let's look first at the gasification route, suitable for solid wastes and residues.
Enerkem's plant in Canada uses non-recyclable and non-compostable waste, thus reducing landfill, to produce up to 38 million litres per year
In Denmark several projects are currently underway (BioReFuel and eSMR-MeOH) using biogas, adding electrolytic hydrogen to soak up the excess carbon, to produce e-biomethanol.
The M2X energy synthesis units produce at a rate of around 1 MW - this would be bigger than most biogas facilities, at least in Germany, so either the substrate or the biogas itself would have to be pooled into each methanol synthesis facility.
Do CO2 demand and supply match?
In our EU model, there is ~400 MtCO2/a from wastes and residues (manure, MSW, straw, forestry residues, etc.).
Demand for aviation fuels is ~135 MtCO2/a, shipping ~150 MtCO2/a and chemicals ~80 MtCO2/a.
So enough in principle to avoid DAC.
Green H2 is still needed to mix with excess carbon in biomass, for ammonia and steel, but transport could be minimised.
Methanol could be used as a hydrogen carrier for e.g. backup power.
Or as a carbon carrier to get e.g. cement emissions from inland sites to coast for CCS.
To summarise:
Electrify everything*
*Use methanol for the rest**
**OK, also a bit of hydrogen for ammonia and steel
Happy to hear comments or thoughts!
PS For further reading I recommend the excellent report by @IRENA and @MethanolToday
Loose rules inside the EU aren't necessarily a problem because we still have the ETS cap-and-trade system, as well as national renewable electricity targets like Germany's that include electrolysis demand.
These provide guardrails on the possible emissions consequences.
The study assumes Germany is isolated and considers electricity system only => caveats
- most hydrogen likely to be used for dense fuels / industry, so long-duration storage you get as "side-effect"
- benefits of electricity interconnection => less storage needed
- hydrogen does not need to be produced locally! could be imported as H2 or derived fuel
=> countries can trade globally to exploit best sites and mitigate local inter-annual variability
You may know the "Dunkelflaute" - difficulty of supplying with wind and sun when both are low.
If we electrify building heating, we double-down on Dunkelflaute, because low wind and sun can coincide with cold periods with high heat pump use and low COP.