https://theconversation.com/even-as-the-fusion-era-dawns-were-still-in-the-steam-age-217273Why are we still reliant on steam?Boiling water takes a significant amount of energy, the highest by far of the common liquids we’re familiar with. Water takes about 2.5 times more energy to evaporate than ethanol does, and 60% more than ammonia liquids.
Why do we use steam rather than other gases? Water is cheap, nontoxic and easy to transform from liquid to energetic gas before condensing back to liquid for use again and again.
Steam has lasted this long because we have an abundance of water, covering 71% of Earth’s surface, and water is a useful way to convert thermal energy (heat) to mechanical energy (movement) to electrical energy (electricity). We seek electricity because it can be easily transmitted and can be used to do work for us in many areas.
When water is turned to steam inside a closed container, it expands hugely and increases the pressure. High pressure steam can store huge amounts of heat, as can any gas. If given an outlet, the steam will surge through it with high flow rates. Put a turbine in its exit path and the force of the escaping steam will spin the turbine’s blades. Electromagnets convert this mechanical movement to electricity. The steam condenses back to water and the process starts again.
Steam engines used coal to heat water to create steam to drive the engine. Nuclear fission splits atoms to make heat to boil water. Nuclear fusion will force heavy isotopes of hydrogen (deuterium and tritium) to fuse into helium-3 atoms and create even more heat – to boil water to make steam to drive turbines to make electricity.
If you looked only at the end process in most thermal power plants – coal, diesel, nuclear fission or even nuclear fusion – you would see the old technology of steam taken as far as it can be taken.
