Constant ENERGY 

pub const ENERGY: CapabilityKey<dyn EnergyHandler>;

Energy, as NeoForge 26.3’s Capabilities.Energy.BLOCK: a block entity’s energy as one side reaches it. The game answers it for a mod block entity’s buffer (block_entity_energy, as SimpleEnergyHandler): its capacity, the most one insert and one extract move, and the sides a fill comes through and a drain leaves by.