Yeah, but that’s not making a huge dent. The EU just isn’t making enough of it it that way—and it’s not surprising, given how much it costs. Even if they weren’t prohibitively expensive, green hydrogen production is only low-emission in theory. In practice… it’s right around the same level of emissions as hydrogen produced from methane (the gray version, not the blue version that’s supposed to include carbon capture, but again runs into the problem of ‘where do you PUT the carbon?’). Nor is the infrastructure needed for a continent-wide hydrogen distribution and storage system anywhere near being ready.
And Finland, by your own link, has developed one commercially-operating sand battery. Just one. Nor does the company have a home-use version, or seem to have one planned. Besides that, you still need to generate the energy needed to heat the sand. So while it’s an interesting idea for a heat-capacitor, it’s not solving any fuel-dependency issues. Given the existence of the second law of thermodynamics, it really just creates more energy demand: because there is no such thing as a 100% energy efficient process, every step of this, from running the steam turbine to transferring the heat into the sand to circulating the air or water needed for heat extraction to transferring that heat into the end-use application… adds inefficiencies, and losses of energy.
The biggest thing that trying to effectively fight climate change is going to come down to isn’t minimizing inefficiencies or finding cleaner ways to generate power… it’s going to need seriously reducing the amount of power we use in the first place. And that… may require reducing the number of people using it. We’re not past the point of food capacity, but we may be above the population cap for safe electrical generation until we experience another massive leap forward in the physical sciences.