Finishing up an honours project dissertation, discovered an engineering law that means the majority of the designed system isn't needed, what do I do? I created a concept offshore pumped storage hydro system using the open sea, pipelines and concrete vessels to simulate the upper/lower reservoirs and conduit of an onshore scheme, where the natural slope of the seabed would act as the head. I designed the concept and how it would all be installed/set up to show that it is technically feasible, while also assessing the economic feasibility ie capital/operational costs and revenue.
While writing my discussion however I came across Torricelli's law, which essentially negates the need of the piping from the surface as the system would perform in the same manner at a reduced cost. I don't really know where to go from here because it means that the majority of my methodology isn't required, and the economic justification would be completely changed as well due to the removal of all the materials/installation costs.
Do I include this in the discussion and just admit that the concept has it's flaws, then list what could be done in the future work? It's due soon so kind of freaking out right now after spending so long designing and justifying it.
Torricelli's law/theorem is not an engineering law (which could be interpreted as having some legal aspects); it is a fundamental result from the physics of fluid flow.
The closely related theorems of Torricelli and Bernoulli are useful starting points for engineering work, but nothing more, since they are highly idealized and involve many assumptions. These assumptions have to do with compressibility of the fluid, friction during flow, wetting of the pipe walls etc.
Since you're doing experimental work, you can actually investigate how much these factors actually affect the intended use  and therefore establish how adequate the theoretical law is. If you focus on it from this perspective, I think your results can be valuable.