
This idea is based off a drillship that runs on electricity by choice, the idea is at the start of the game you are going to have a choice to stick with the original core
or build yourself a new core called the electrical core, if you choose to craft this core its going to upgrade your core to the electrical version but in order to get this version of the core you are going to need to build it in the production bench with upgrades with resources, the storage for the electricity for your core is a new bar that is added to the electrical core that is upgraded as you upgrade your core. This craft would be available anytime in the game.
The power that your ship needs to run is generated by modules like the windmill, solar panels, or buildings that players or the creators come up with. The battery idea can come into this to because if you have the electrical core the batteries can extend the battery level for your electrical core powered ship by storing extra power that is used when you run out of core power traveling underground
A new building that I came up with that can use the lava rivers as a power source,
This building works like a dam it generates power and shoots it back to your drillship and retracts into their side of the lava river mountains like the cog drills before a explosion, by spliting down the middle and both parts retracting to their side, deployes by both coming out of their side of the mountain and reconnecting. The way that your drillship recieves this power is a new modual that you create called a reciever that only works when the drillship is fully deployed.
Something like this picture