Generators and batteries and all that goes along with them may cost hundreds or thousands of Euros, perhaps constituting the most significant cost in some systems. So I think it makes sense to try to avoid using them.
What are some ways you can use rotational energy without using a generator?
I am most interested in directly using kinetic energy to heat water, as I think that is the biggest market. What are some products I could buy or make now that would do that and that would end up costing less than using a generator to generate electricity?
As a start: