Poul la Cour had conflicting feelings over his latest development. It wasn't the grand invention that would change the world, but rather another helpful but unremarkable part of a whole.
But it had the potential to be profitable. And, as his correspondence with Dr. Hess in Sicily suggested, it was profitability the key to funding. It was the reason why scientific and technical magazines and journals were slowly moving articles about solar-powered devices from the back to... well, not the cover, but a place of prominence. Why the language describing them had changed from short accounts describing curiousities in remote places like Egypt and Chile, to serious analysis of the sun's potential as an energy source.
And it was the reason why Augustin Mouchot's water heaters were advertised in French magazines, when a decade prior his work was all but forgotten.
And it was that which gave him hope. What his device lacked in ambition (as it was just an adaption of Joule's demonstration of the heat-work equivalence), it made up with practicality. A wind turbine connected to an impeller inside a water tank.
It worked well while the wind blew. Water heated up, then boiled, keeping the house pleasantly warm.
And when the air was still... it was a catastrophe at first. The water reservoir froze solid and once winds blew again, it shattered the turbine. He experimented with oil, which was expensive, and antifrost mixtures, which reduced the machine's efficiency. A centrifugal regulator and a simple electric heating element, powered by the same turbine, were enough for the system to start working again after a stoppage.
Poul was an inventor, and so he knew that investors would only come if they were certain of the machine's capabilities. So he tested the machine for a whole month. He willingly pushed it to its limits, and it proved itself. The reservoir could freeze if the blades stopped, but the heating elements guaranteed a film of liquid water which could lubricate the block of ice, allowing it to move and then melt and boil.
And sure, the machine had its limitations. It would always need a coal boiler to complement it when the winds didn't blow. Or at least until somebody invented a way to store large quantities of heat.
But that was a problem for another time. Today, Poul La Cour had something in his hands that would be profitable. Something that would allow him to fund more ambitious research.