Gas Turbines

Gas turbines run off flammable gases. The main fuels for these are refinery gas, naphtha, biogas, benzene, and random waste gases from oil processing. There are 3 tiers of single block turbines and a multiblock turbine, similar to steam turbines.

Single Block Turbines
There are 3 gas turbines added by Gregtech, providing LV-HV power. Efficiency decreases slightly with higher-tier generators. These turbines use their fuel intelligently- they only produce as much power as needed, and turn off if there's no power draw at all. They don't ever lose fuel over time, don't waste fuel idling, and don't need lubrication.

Basic Gas Turbine
The basic gas turbine is available at LV. It produces 1 amp of LV power (32 EU/t) at 95% efficiency.

Advanced Gas Turbine
The advanced gas turbine is available at MV. It produces 1 amp of MV power (128 EU/t) at 90% efficiency.

Turbo Gas Turbine
The turbo gas turbine is available at HV. It produces 1 amp of HV power (512 EU/t) at 85% efficiency.

Multiblock Gas Turbine
Available at early EV, there is a large gas turbine. It is bigger, more complicated, and more expensive than single block generators, but can get much higher efficiency. It requires a rotor, which determines the efficiency and amount of energy produced per tick. Note that unlike the single block turbines, these always produce 100% of their energy output, even if it's just going to waste. Be careful with these- if you make more power than the dynamo hatch can output (I.E. make 2400 EU/t with an EV dynamo hatch) then the turbine will EXPLODE. The power produced is based entirely on your choice of rotor, from 150 EU/t with cheap, low-quality material small rotors, to 25,600 EU/t with a huge infinity rotor. Unlike steam turbines, gas turbines will allow excess fuel to sit in the input hatch until it's used, and won't waste any extra fuel.

Rotors
Rotors work more intuitively with these than with steam turbines- they simply say how much EU they'll produce per tick. Based on what fuel you're using, and the efficiency of the rotor, the actual amount of fuel you need varies, but the amount of EU produced stays constant. There are small rotors available at MV, regular sized rotors, available at late HV, large rotors available in EV, and huge rotors available once you've obtained a fusion reactor. Larger rotors process more gas and are generally more efficient, but are more expensive. Rotors are also used in large steam turbines and in large plasma turbines.

Oil Products
Oil products are the main source of gas turbine fuel. Gas turbines can be ran off refinery gas(giving 160,000 EU per cell) or naphtha (giving 320,000 EU per cell). In addition to these, once you've obtained a distillation tower, there are many odd random byproducts of oil cracking that can be put into a gas turbine, to generate a little bit extra power, if they're not used for anything else.

Biogas
Biogas is an easy-to-make renewable fuel source. 1 cell of methane can be distilled into 3 cells of biogas, 10L of IC2 biomass can be distilled into 16L of biogas (or 3 cells to 8 cells in a distillation tower), or 10L of fermented biomass can be distilled into 18L of biogas. One cell of biogas produces 40,000 EU. Biogas isn't particularly efficient, but is very easy to make. Biogas can also be used to power an IC2 Jetpack, which is less efficient than powering an electric jetpack and using the biogas to produce EU, but one tank of biogas lasts a lot longer than a full electric jetpack, and is easier to refill on the run.

Benzene
If you want to use gas turbines as your main fuel source, a pyrolyse oven will allow you to do that! This is a fairly complex processing line but produces a lot of fuel. Use a pyrolyse oven to produce wood tar and charcoal, and have several fluid extractors to fluid extract the charcoal, which will give you extra wood tar. After that, put the wood tar into a MV distillery, and distill it into benzene. This method is complex to set up, and uses a lot of wood, but produces a lot of power and is fully renewable, as well as giving you a bunch of ash (from fluid extracting charcoal) which can be turned into fertilizer to grow more wood.