Hydrocarbon Fuel Cells for 3e
 

So, I've been working on a CnC Tiberium/CnC Generals fusion (with some bits from the Earth 21X0 series and Act of Aggression) for a 'remake CnC' setting and one of the things is that most of the petrol/diesel/aviation gas is gone, most of the oil deposits are gone and the majority of the infrastructure for its creation is consumed by a certain von-neumann crystal.

So, GDI is currently using propane/LNG to fuel the engines for its vehicles until proper proton-proton chain fusion reactors get produced in sufficient numbers for mass deployment on vehicles. Using LNG makes things, oddly enough, worse. An LNG-fueled ceramic engine for what is a Humvee requires (for a 10-hour fuel duration) almost 3.5 metric tons of LNG (or 6,814 liters/1800 gallons).

I've checked MA Lloyd's Vehicle Expansion and it makes an LNG-powered fuel cell even worse:
It is almost like it's forcing you to go fusion as soon as possible and damn the consequences.

From my understanding, RL HC-FCs would be taking a third of the fuel consumption of their standard hydrogen counterparts... not half again. In addition, an HC-FC is 2.375 times heavier than the equivalent supercharged ceramic engine using LNG while having a fraction of the fuel consumption...

If there is a way to make HC-FCs work, I would be glad to hear it.

Re: Hydrocarbon Fuel Cells for 3e
 

How about giving them the same weight and price as the VE2 hydrogen fuelled ones, and giving them a multifuel consumption equal to the listed hydrgen consumption times the ratio multifuel to hydrogen given for IC engines (so about 0.02 gph at TL9+). This makes them economical but heavy.

Note that there are other options aside from fusion - fission reactors are lighter and cheaper at TL9. Also, rechargable powercells can be lighter and more compact than engine plus fuel for shorter durations (exactly how short depends on the engine and fuel), which can be over 12 hours.

One other thing - do these extra rules use realistic fuel consumptions (VE2X p.23) and thus give consumptions three time higher than VE2 assumes?

Re: Hydrocarbon Fuel Cells for 3e
 

Please note that using gas turbines would balloon my fuel requirements, especially since my setting has ETC guns (firing AP ammunition) as standard.

To give you an idea, I'll give you three different engines using standard vehicle calculations:

• Ceramic Engine (Supercharged, LNG fuel): 4MW output, 88111lbs/3997kg weight, 180gph
• Gas Turbine (standard, LNG Fuel): 4MW output, 4417lbs/2003kg, 330gph
• Hydrocarbon Fuel Cell (LNG Fuel): 4MW, 2025lbs/9083kg, 153gph (/3)/80gph (multifuel modifier)

With a running time of 10 hours being an outright requirement (because, well, a certain von-neumann crystal ate most of the oil fields and associated infrastructure outside of, essentially, those in enemy hands), you can see where this is going.

Note, the current Humvee equiv has an engine grouping (fuel and all) of 22281lbs/6677kg in terms of mass.
Are they MHD Turbines or something else?
MA Lloyd's Vehicle Expansion says this:

Re: Hydrocarbon Fuel Cells for 3e
 

The problem is likely that hydrocarbon power plants in Vehicles have about 1/3 the fuel consumption they realistically should have (though this is somewhat negated by the way operating endurance is calculated), and thus realistic options look bad.

Re: Hydrocarbon Fuel Cells for 3e
 

True, and let's be honest, by tripling the fuel consumption, we'll get immense problems with getting fuel, especially when you've only got, say, a Fennek's volume to work with and need a good operational range while carrying five guys in power armor.

A Fennek has an operational range of... 860km/530 miles and it's roughly 10.4 metric tons (or 11.5 US tons). In comparison, my current humvee-type vehicle has a 10-hour operational time, can move at 64.4km/h off-road, and weighs in at just a smidge over 24 metric tons.

It makes the rules rather hostile to ICE in general.

Re: Hydrocarbon Fuel Cells for 3e
 

Not really, because most vehicles don't move at maximum speed all the time. If it's doing ~30 km/h off-road rather than the maximum, it will be using 1/4 the power and thus 1/4 of the fuel it uses at full speed/power.

Re: Hydrocarbon Fuel Cells for 3e
 

Those engines are _huge_ both in weight and output. 4 MW is more than 5000 horsepower.

Also, when I google "Humvee" I get a max weight of maybe 8500 lbs for the whole thing and not just the engine and gas tank.. Not sure what your 2.5x as large vehicle is.

It seems possible to me with those engines that your vehicle size and performance goals are too large for the setting's resources.

Re: Hydrocarbon Fuel Cells for 3e
 

Video game developers and TV script writers are not always known for doing in-depth research into technology before slapping a definition on something. I suspect that the source material played pretty fast and loose with stuff.

Re: Hydrocarbon Fuel Cells for 3e
 

Just for real-world scale:

Actual HMMWV engine: 0.15 MW
M1A2 powerplant: 1.12 MW

So a 4MW power plant is enough to drive more than three M1A2 MBTs, each of which masses over 62 tons.

https://www.siemens-energy.com/globa...s/sgt-100.html

This is a 5-ish MW gas turbine by Siemens.

https://www.siemens-energy.com/globa...s/sgt-100.html

it masses 27 tons by itself.

Re: Hydrocarbon Fuel Cells for 3e
 

True, but you want to get out of the area with Tib ASAP or it'll eat your vehicle...
Yeah, kind of hard to keep the power generation low when you need ADS systems as standard (in this case, a 2mm gatling railgun and a 1.6MW gatling UV pulse laser per turret), have various power-hungry sensors (high-res LIDAR, I'm looking at you) to stay relevant, your main weapon is an Electrothermal Chemical gun (with slightly heavier rounds than what's used in Vehicles) backed by a revolving missile launcher, and a 2MW main wheel drivetrain.
Blame the fact that it has a lot of sensors (AESA, Multi-Res LIDAR, Multiscanners, etc.) and ETC weapons firing moderately heavy projectiles at a decent RoF. Please note that, with the humvee equiv, the total power consumption is 3,233kW minus the two 50kJ/RoF50 1.6MW gatling UV lasers.