PowerTub is a design for converting power into electricity.

We already have thermal power plants, which convert heat produced from burning coal/petrolium into electricity. And we have hydroelectric plants/wind turbines, that convert flow of water/air into energy.

Both of above mechanism convert motion into electricity. In later case motion is driven by water/air. In former case energy source is used to boil water, which releases steam under a lot of pressure, and the pressure differential is used to drive motion, which then generates electricity.

Nuclear power plants too work on the similar principle, the generation of heat is carried out by nuclear fission process, which is used to boil water and generate electricity.

PowerTub is a slight modification on these designs.

PowerTub is a massive reservoir of water, which is air tight, so as to allow steam to be harnessed.

The reservoir of water serves one another purpose, along with usual purpose of steam source. The purpose is impact absorption.

1. Energy from the sky

The reservoir is built in a fashion to allow opening at top if heat source is going to be dropped at incredible speeds. The top would open momentarily to allow the object to fall, and close right afterwards to trap steam, which gets produced when the falling hot objects boils the water in the reservoir.

The impact could be tremendous, so reservoir has to be considerably large.

The energy brought could be either purely gravitational, e.g. imagine throwing comets into the reservoir, with rockets strapped on those comets to lower the speed just enough that it does not burn up in air.

Other possibility is massive astroids which are taken close to sun, put in front of a focusing mirror, and melted on the inside, and then bringing that massive molten rock using rockets and being thrown at controlled speed in the PowerTub.

2. Energy from the atoms

The other possibility explosion of nuclear fusion bombs in the water.

The reservoir of water will have a bomb placed in the water, and exploded. The reservoir has to be built to withstand the explosion, and trap more or less all generated energy.

The reason currently we are not using fusion as a power source is because there is no way to create controlled fusion reaction.

PowerTub design can work around this problem by not requiring a controlled fusion, but relying on the massive amount of enclosed water to enclose the impact.