As you've rightly worked out, power is a mechanic that isn't yet in the game. I'm surprised that there are recipes in the game that demand it, they shouldn't really be there yet as you won't be able to build them.
To increase the power of your machines you will place engines around the machine which automatically connect to it. The more engines you add, and the better the engines are, the higher the power is.
Power does two things - it gates some recipes (as you've seen) and it also makes crafting quicker and therefore use less fuel. This is so that whilst crafting is readily accessible to all players, those with massively powered up machines will produce high end things quicker and cheaper. This allows a specialist crafters to craft in bulk, and make a profit as some players choose to buy rather than take the time and resources to craft something themselves.