ICE vs. Fusion Engine Costs

[Daryk]

Doing some basic calculations on fuel use (from Campaign Ops, page 24) and comparing that to the difference in cost for fusion (out of Tech Manual), it seems the heavier the vehicle, the longer the payback period for switching to fusion.  For a 5 ton jeep with a 10 rated engine, the engine cost differential is made up in about six and a half months, making it completely worth it.  A Heavy Battlemech Recovery Vehicle, on the other hand, will take a bit over 10 years to burn enough fuel to make up the difference.  Of course, that assumes fuel is available at the lowest price.  Trying to procure the stuff in a war zone will certainly make it more expensive, if it can be had at all.  While the argument for fusion engines for everything is still strong on that basis, the economic case gets weaker the larger the engine (and by extension, the vehicle) is.

[Teulisch]

heavier vehicles also devote more weight to a large ICE, so that means an upgrade to fusion will also free up tonnage for other things, like armor and weapons.

for example, the bulldog. 23 ton engine, and a half ton of power amplifiers, and 8 tons for heat sinks. a fusion engine of the same rating is only 11.5 tons, and you no longer need those heat sinks (fusion gets 10 free), or the power amp. 20 tons suddenly free for other things... thats a massive strategic advantage.

so the engine cost is more than just the engine. its the tonnage. and that can be a large change to the BV of the vehicle.

[Fallen_Raven]

Are you factoring in maintenance as well? Because you aren't hiring a fusion qualified technician at Jiffy-Lube prices, and your fancy fusion engine isn't paying off anything if its not working.

[Daryk]

Technicians cost the same regardless of their specialty (page 25 of Campaign Operations refers).

[Col Toda]

Combat vehicles are attrition units . They get in the fac3 of the enemy slapping TAG or NARC in a support role or in fast as both area denial capacity or givevan imperitive to shoot at cheap disposable irreplaceable units . Fuel Cell is among the best way to go as it has the same motive power as a light Fusion Engine . and costs about 2/3 as much as a standard fusion engine . This is a question or replacing destroyed losses more than repairing damaged ones .

[Empyrus]

Some thoughts:
Wouldn't logistics advantages be the true cost saver of fusion engines?
An army powered by fusion engines only doesn't need a fleet of tankers, allowing logistics train (and assuming all those also run on fusion) to focus on other essentials. Less stuff needed, the smaller and safer the logistics are.

While fusion isn't technically fuel-free, water - source of hydrogen - is most likely easier to come by than any other fuel (be it hydrocarbon or ethanol or whatever else that works). (As long as you have at least some kind of backup power system and water, whether it is solar panels or man-powered treadmill generator, hydrogen supply for fusion is more or less assured.)

Of course, the practical and economic realities of the Inner Sphere indicate that pure fusion military is either impractical or just not needed. For example, a defender most likely doesn't need to worry nearly as much about fuel logistics as the attacker, fuel caches can be prepared in advance, and simpler ICE-powered combat vehicles can be produced cheaply and in numbers. And  many worlds that are targets for invasion are relatively advanced, so it shouldn't be too hard for the attack to secure a local fuel supply.

Interestingly, the Clans are great believers on pure fusion military but they evidently still have uses for fossil fuels, i do wonder if they use those for fuel or for other products (chemicals, plastics, etc.) though?

[idea weenie]

Fusion engines might need higher training for their technical personnel, while ICE deals with much lower power levels and lower skill requirements.

So by using ICE powered units you can still put a combat unit on the front line, but training your technical personnel is much faster.  This allows growing your logistical tail much faster than if you needed the full nuclear training.

As a comparison:
United States Navy Gas Turbine Systems Technician - 10 weeks of schooling
United States Navy Nuclear Electronics Technician - 18 months of schooling

I still expect there is a fusion powered unit at the refueling depot, whose entire purpose is to convert atmospheric nitrogen and carbon dioxide into ammonia fuel, or charge batteries, or crack water into hydrogen and oxygen for fuel cells.  This keeps the physical logistical needs to a much lower level needed, and you only need one set of nuclear trained technicians, instead of needing multiple sets to support all your vehicles.

This could be part of the job of a supporting Dropship, where it processes local materials into fuel for the embarked combat unit.  This way you have the Dropship's nuclear trained crew taking on the responsibility for the power supply, instead of the unit needing to have its own nuclear trained personnel.

[Daryk]

I'll note AToW (pages 82-85) lists Technician/Nuclear as part of every skill field with "Technician" in it (Civilian, Military, Aerospace, 'Mech, and even Vehicle).

[marcussmythe]

In many cases a given Fusion vehicle with a fixed equipment package will he cheaper than its ICE counterpart, due to the smaller engine required to make speed and this the overall reduction in vehicle mass.

Now, not all places can produce or maintain fusion engines - and this may explain the continued use of ICE - but this makes me ask why, if the fusion is so superior as to allow enough weight savings to make a cheaper unit, that price per engine has not heen bid up to the point where the unit is no longer cheaper - because the knock on effects in crewing, fuel logistics, and in transport of the vehicles themselves to the battlespace suggest that everyone would always want the fusion vehicle, even without the cost savings.

[Colt Ward]

Yeah . . . and if you are running combined arms, a fusion powered vehicle force is going to have additional benefits.  The spare for your old Centurion is sitting over there in that Myrmidon.  The same Myrmidon can also recharge the power packs for the infantry's laser & MagShot rifles along with the Battle Armor suits.  When I set up my command post, I just plug in to the Myrmidon's power net- maybe along with its com links.

ICE is a defensive force technology, Fusion is for offense . . . to the point your support/supply elements should also be using it as much as possible.  Look at the logistical tail planning, you can only push supplies forward to a point that the tail actually ships something besides fuel and food for the drivers to get out to X distance.  Desert Storm and Iraqi Freedom logistical planning is a good starting point since in that environment you were not going to be able to requisition local food or water to supplement what could be trucked in.  The closer a force is to its port/railhead the greater the operational tempo is going to be . . . for example, a War Dog pilot with a full load is going to be firing that Gauss Rifle a lot more often on less optimal shots than say the Huron Warrior with its single ton (or is it two?).  And its going to apply for the dropships carrying ICE fuel for the ammo and repair vehicles that would be servicing mechs & armor- the less fuel you have to haul along for the support vehicles, the more ammo & armor you can haul.  Additionally, its going to free your planetary strategic planning in the opening phases.  Instead of making one of the first objectives of a planetary invasion a refinery or fuel depot- and being a obvious target to the defender- it gives the offensive planner more latitude to seize ground that is more direct in achieving the final objective.

[Daryk]

Honestly, even on the defense (at a planetary scale) fusion makes more sense than anything requiring fuel.  All the things you mentioned get better for the defender too when they don't have to move fuel.

[SCC]

Doing some basic calculations on fuel use (from Campaign Ops, page 24) and comparing that to the difference in cost for fusion (out of Tech Manual), it seems the heavier the vehicle, the longer the payback period for switching to fusion.  For a 5 ton jeep with a 10 rated engine, the engine cost differential is made up in about six and a half months, making it completely worth it.  A Heavy Battlemech Recovery Vehicle, on the other hand, will take a bit over 10 years to burn enough fuel to make up the difference.  Of course, that assumes fuel is available at the lowest price.  Trying to procure the stuff in a war zone will certainly make it more expensive, if it can be had at all.  While the argument for fusion engines for everything is still strong on that basis, the economic case gets weaker the larger the engine (and by extension, the vehicle) is.

I'd start by adding one K-27 to your costs per lance of ICE powered vehicles, after all somethings got to haul that fuel around.

Are you factoring in maintenance as well? Because you aren't hiring a fusion qualified technician at Jiffy-Lube prices, and your fancy fusion engine isn't paying off anything if its not working.

Technicians cost the same regardless of their specialty (page 25 of Campaign Operations refers).

This should be very timeline dependent, but during the Star League era I'd assume that an ICE technician would cost more, just like it would cost more to hire a guy to work on a steam engine these days. In general fusion techs should probably be considered the default in BT, just like ICE would be today.

Of course, the practical and economic realities of the Inner Sphere indicate that pure fusion military is either impractical or just not needed. For example, a defender most likely doesn't need to worry nearly as much about fuel logistics as the attacker, fuel caches can be prepared in advance, and simpler ICE-powered combat vehicles can be produced cheaply and in numbers. And  many worlds that are targets for invasion are relatively advanced, so it shouldn't be too hard for the attack to secure a local fuel supply.

Interestingly, the Clans are great believers on pure fusion military but they evidently still have uses for fossil fuels, i do wonder if they use those for fuel or for other products (chemicals, plastics, etc.) though?

Most armies are probably going to assume that ANY unit could be forced into the attacker role at any time, and then what happens to your nice cheap ICE's? There's also the fact that the infrastructure to store that fuel has to be paid and maintained.

[Daryk]

Adding in an extra vehicle (and it's attendant crew and maintenance techs) will certainly shorten the payback period.  Simplified logistics continues to be the main benefit of fusion engines...

[Col Toda]

The engine is normally the single most expensive item in a combat unit .  When you factor 1 the offense because of logistics may have all fusion units and 2 combat vehicles are ment to be attrition units it is essential that you do not gift near immediately battlefield salvage to the enemy that can be quickly fixed and used against you .  So if the attacker has all fusion spare parts and no fuel cell or ICE spare parts all they can do with tanks that have to be abandoned on the battlefield do to ammo explosion with CASE or immobility is stow them aways as cargo . If it is fusion powered they fix it and put their own crew in . As for fuel as a defender fuel depot should be everywhere you are defending anyway

[Daryk]

"Fuel everywhere" is pretty expensive infrastructure to maintain...

[Colt Ward]

"Fuel everywhere" is pretty expensive infrastructure to maintain...

I do not think its everywhere per se, its 'everywhere you want to defend'

So yeah, there is going to be a FP/fuel dump at that garrison post that guards the spacehead (or railhead) where the mines' refined production is stored before hopping over to the coastal factories.  Anywhere you place a garrison force, you are going to have fuel present.  On top of that, the ICE engines are supposed to be configurable so they should be running on whatever is used to power the civilian market so anywhere you have a collection of civilians you should have a fuel supply- question is, is it enough?

[SCC]

You guys are forgetting weapons costs by using an ICE, autocannon and missile weapons require ammo, which costs money to maintain, and id you try to dodge that by using energy weapons, well you'll need a LOT of HS, and it's usually cheaper to actually switch to using a SFE and reduce vehicle weight in those cases.

[Col Toda]

The Standard Fusion Engine VS ICE for attrition units means every destroyed vehicle just lost an engine . Fusion engines costs 4x than an ICE and after shielding weighs 50 percent less . For Fuel Cell you have to compare it to a light fusion engine which after shielding weighs about the same for the same motive power . So as a defender you win out big with fuel cells but the attacker can have a more remote LZ with fusion . That is the only real advantage fusion has a larger operational radius . So for every victory insured by the sacrifice of a lance or so of mass produced combat vehicles costing 3 million C biils each the same vehicle with a light fusion engine would cost 4.5 million each approximately . As an attacker the strategic operational radius may be worth the surcharge but as the defender it is not .

[boilerman]

As an attacker the strategic operational radius may be worth the surcharge but as the defender it is not .

That's pretty much how I see it, although I have always thought fusion engines were too cheap relative to the cost of an ICE.

[Col Toda]

 " A Time of War Companion " Gives I think Joe Q Planet something like 60 million C bill a year operational budget.  Say you put aside 10 percent to replace combat loses . You can replace more destroyed units of ICE and Fuel Cell than fusion . High performance combat vehicles use XL engines which by itself cost as much as 2-4 non fusion engine .  So Just saying replacing cheaper units is easier .

[Daryk]

For planets taking those kind of combat losses, sure.  But for the vast majority, the saved ongoing fuel costs (not to mention not having to pay for a fuel handling infrastructure) will make up the difference.

[Col Toda]

A petrochem industry making fertilizer and ocean going transport very well may be in place in a primarily agriculture world . If the civilian infrastructure is in place not too hard a stretch for military to take advantage of it too . Remember in fluff text for the Romel and Patton tanks the fusion engines are replaced by ICE in the Draconis Combine and slows to a 3/5 speed . Old very established planets have the Star League efficiency of distribution as the priority not Defense . As a result production is spread out and any product made groundside can be loaded on small craft and put on orbiting drop ships or stations with minimal ques and congestion . After the Secession war new colonies are designed for defense not distribution .

Objective raids are done when a loaded Union drop ship can at the point of contact has the force to defeat defenders that can be brought to bear . Having cheaper ICE units means in a wildly distributed choice of targets you can have more physical units in place to defend them .

[Daryk]

Again, it depends on the loss rate.  The higher capital costs of fusion engines are made up relatively quickly by fuel avoidance.  Over the long run, you can afford just as many fusion vehicles as ICE ones.

[massey]

During the Succession Wars, there was a shortage of fusion engines that is not reflected in the cost.  Enough fusion engines for your vehicle army simply are not available.  Not at any price.

[Daryk]

Except for that huge cache of 25 rated engines that got the Savannah Master in production...

[kaliban]

ICE is not really cheaper than Fusion, as long ICE vehicles are bigger and carry heavier missile and ballistic weapons. Fusion engines allow inexpensive fast and small vehicles armed with energy weapons, that do not depend on fuel or ammo.

ICE is just a fluffy thing to balance the game and keep the edge of the Battlemechs. You partially break it with Fuel Cells and, for no other reasons, Standard construction rules do not consider fuel cells in combat vehicles.

Like to design vehicles with ICEs just because it is very challenging to make good ones

[CapricornNoble]

I'm working through these sorts of design/logistics challenges right now, here's my actual numbers below. Note: Not posting the full designs because those go in the Fan Designs forums, right? BUT........ Two 50-ton tanks, roughly analogous to a T-72 or Chinese Type-96B. Alternatives to the Po and the Vedette in the BTU....

Tank #1:  ICE engine 4/6MP, LB-10X w/30 rounds, thinner armor.
Tank #2: XL Fusion Engine 4/6MP, Gauss Rifle w/32rounds, heavier armor.
Personnel quantity and cost columns are omitted here, but they are 4 vehicle crew, 1 tech, 6 astechs, and 1 admin for both vehicles, all with salaries from AToW (per the suggestion in CO). I use the Euro currency symbol to denote C-Bills in my spreadsheet. The fuel cost is $1,000 CBills/ton for petrochemicals as per SO pg. 179. All numbers are monthly unless indicated. Units were designed in MegaMek 0.47.0. and key data was hand-jammed into my master LibreOffice spreadsheet.

Nomenclature	Ammo (tons)	Ammo (CBills)	Spare Parts (tons)	Fuel (tons)	Cost incl. Salaries	Annual Cost	Unit Procurement Price
50t MBT-ICE	1	€15,750	0.05	1.7	€22,950	€275,400	€1,340,500
50t MBT-XLF	1.375	€20,625	0.05	0	€27,825	€333,900	€5,646,250

As you can see, the maintenance cost delta is ~$58,000 per year, the bulk of which for both tanks is ballistics ammunition. It would take the XL Fusion MBT ~70 years to recoup its significantly higher purchase price. Something like $2.6M of that price is the engine IIRC.

On the subject of range and logistical requirements....I'm working through some conceptual scenarios in SBF to determine what is a reasonable log tail. ICE/fuel cell combat vehicles have ranges of 450-600km, which is enough to move 1 hex.....at the 84-hour, 750km ACS scale. Topping off the fuel every 2-3 days isn't unreasonable, the crews will need to rest at some point anyway. Pushing people past 36-48hrs of continuous ops is a bad idea.

SBF is 500-meter hexes @ 3-minute turns. The real question is "How far are you willing to land from your objective?" and "How much time will you allow for your opponent to prepare his defense?" If you want your LZ outside of artillery range from the objective, the longest-ranged arty is I think the Cruise Missile 120 @ 153 SBF hexes (~75km). Anything smaller than a cruise missile maxes out at <16km. If you are confident the defenders won't be lobbing Iskander-Ms at your LZ, you could probably land ~50km from the OBJ or less, giving yourself some wiggle room in case they come out for a meeting engagement or spoiling attack. If you stick with this style of assault, the need to drive >600km unrefueled should become moot, and the cost of refueling, even accounting for POL trucks and supply personnel, should barely be a rounding error. Note: I haven't finished my SBF Formation TO&Es with all logistics vehicles yet so I don't have Campaign Ops costs worked out for discrete company-sized units completely....just the bulk of the combat arms stuff. I might have to totally re-jig some vehicle designs as a more thorough reading of the SBF rules seems to indicate you can't really set up a Support By Fire position in an adjacent hex and really capitalize on your Long Range fire values. You can only shoot from an adj hex if you can do Indirect Fire or Arty attacks. Unless I'm reading things wrong....

But anyways, I'm willing to skimp on PROCUREMENT cost as the operating expenses of ICE or Fuel Cell vehicles, outside of the brutal "ammo usage during training" part fit within my tactical/operational doctrine. I'm only considering Fusion on certain vehicles where I REALLY wanna stuff maximum lethality in my 50-ton light vehicle bays.

[Daryk]

XL engines are complete other animals.  And I already pointed out that the pay back period is longer the heavier the vehicle is...

[Daryk]

Also, on the strategic level, you're going to want to go for 45-ton tanks for the one less crew person.  A 4/6 45-ton tank with a Gauss Rifle can run under $1.5M, so it would only be making up about $400K of initial outlay (compared to an equivalent 45-ton ICE tank with an LB-10X).

[Kovax]

A 4/6 45-ton tank with a Gauss Rifle can run under $1.5M, so it would only be making up about $400K of initial outlay (compared to an equivalent 45-ton ICE tank with an LB-10X).

So, it would "only" take about 8 years (give or take a couple) for the standard Fusion engine vehicle to recover the cost difference.  For a planet facing regular raids and invasion, that may be longer than the life expectancy of the vehicles.  For a permanent garrison in a quiet sector, the fusion power plants would eventually be cheaper, if they're available.  The "available" part is the sticking point: during the Succession Wars, most fusion power plants were in short supply, so if you're losing 30 tanks per month, and only able to manufacture 20 fusion engines, there are eventually going to be either a lot of Internal Combustion Engines being used in your armor formations, or else heavily understrength tank formations.  It's not so much a matter of what's "better", but about what's available.  Cost differences are irrelevant if you can't buy the one.

Move the timeline ahead to the 3060s, when fusion engine production is no longer a major bottleneck, and either fusion or fuel cell engines are going to be more practical than standard Internal Combustion Engines for most applications.