Energy is a type of currency that players can use to accomplish things in a Virtual World.
Energy can currently be obtained in two ways:
Most towers will grant 100 Energy, except for the Cortex and Volcano towers, which grant 20.
Virtualizing will also grant 100 Energy if no Software Attacks prevent that.
The things you can use energy for will vary. Their most notable use is spawning an Overvehicle.
Some events have used Energy as an objective to obtain in a quest, like to open the access to the Cortex Core.
You might find yourself short of energy while your friend has plenty. It is possible to share energy with each other through the Virtual Menu.
Access the Virtual Menu with Shift + L (or just L while on an Overvehicle) and click the lightning button. There you can select a player to send energy to, and specify the amount.
You can't send energy to another player if:
There's two ways to see how much energy you have:
In the Virtual Menu you can hover over the lightning bolt to see how much total energy you have.
The /lw info command will show you a detailed list of how much energy you have and what type they are.
Energy comes from Virtual Worlds. Each virtual world has a pool of energy that players can access through the above methods.
Energy is generally interchangeable between worlds. This means that you can spend Lyoko energy in the Volcano Replika, or vice versa. It is possible that you are asked to supply a specific type of energy, however.
Energy exists in a closed loop. Once energy is released (for example, when an Overvehicle is dematerialized). it returns to the virtual world of its origin.
This also means that if you were to deactivate a tower and there is no energy left in the Lyoko pool, you won't receive energy.
Before the energy rework update, the concept of “free energy” existed, which was energy that could not be transferred and would disappear on release. It was created as a result of virtualization in a drained virtual world.