Energy Units

Energy Units, or EU, is one of the oldest forms of energy in modded Minecraft. It is added by IndustrialCraft 2 and is consumed primarily by it's machines and related addons. EU acts as a form of electricity, similar to real electricity in some ways.

Production
EU is produced through Generators. IndustrialCraft adds many different generators, but the (standard) Generator, Solar Panel, and Geothermal Generator are the most basic ones. The most powerful generator in IndustrialCraft 2 is the Nuclear Reactor, capable of outputting thousands of EU per tick, but requiring careful design and automation to do so.

Addons and other mods, such as GregTech, add additional, more powerful generators.

Transport and Storage
EU is transported via wires and cables. The most basic cable is the Tin Cable. Wires can be insulated with Rubber to form Insulated Cables, which lose less energy. Uninsulated cables will, as well as transfer energy less efficiently than Insulated Cables, deal shock damage to any entities that are too near or touch them (while this is hazardous, it can be used to build mob farms and traps). All cables are rated to carry a certain amount of EU per tick. In older versions, if their limit is exceeded, they will melt, however, for developmental reasons, the transfer limits on cables are currently disabled.

All IC2 Generators and machines store a small amount of EU internally. However, most EU is stored in dedicated EU storage blocks such as the BatBox or MFSU, or another device added by an addon (such as the AFSU). MFEs also accept EU. Copper Cable can be used to channel energy if needed. Especially when charging a MFSU, you'll need several Generators, and using Geothermal Generators are the most efficient, especially if you're using Lava Cells, as they generate the most EU/t for anything. Lava Cells produce 20k EU/t at Geothermal Generators.

EU can also be transported and stored in items. IndustrialCraft 2 adds several electric tools and suits of electric armor that consume EU instead of durability, including the Electric Jetpack and the Mining Drill. Additionally, the RE-Battery, Advanced RE-Battery, Energy Crystal, and Lapotron Crystal are a set of items used primarily as crafting components and as portable rechargeable energy storage objects. However, the Lapotron Crystal is not accepted by all energy storers. The MFE will not accept the Lapotron Cyrstal.

Pre-IC2 Experimental
In July, 2013, as IndustrialCraft 2 was being updated to Minecraft 1.6.2, much of the mod began a substantial re-write, resulting in the creation of the IC2-Experimental branch. One system that was rewritten was the EU system. While the rest of this article details EU in its current state, this section will discuss its earlier (Minecraft 1.5.2 and earlier) aspects.

GregTech 5
GregTech 5 uses it's own system of EU, designed to more closely match the pre-Experimental EU system.

GregTech cables and Battery Buffers can output EU normally to all EU-accepting blocks, but will not accept EU from non-GregTech sources. However, a Transformer will accept EU from outside sources, and emit GregTech EU.

Usage
EU is consumed to operate machines. Many mods use EU, including but not limited to:
 * IndustrialCraft 2 and.
 * MineFactory Reloaded.
 * Modular Powersuits.
 * Applied Energistics/Applied Energistics 2.
 * All mods that implement Universal Electricity, including MineChem, GalactiCraft, and Modular Force Field System.
 * RotaryCraft (via the Electric Motor).