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Comprehensive modeling study finds electric drive vehicle deployment has little observed effect on US system-wide emissions

The results of a new, comprehensive modeling study characterizing light-duty electric drive vehicle (EDV) deployment in the US over 108 discrete scenarios do not demonstrate a clear and consistent trend toward lower system-wide emissions of CO2, SO2, and NOx as EDV deployment increases.

As explained in their paper published in the ACS journal Environmental Science & Technology, the researchers from North Carolina State Univesity and the University of Minnesota found that, while the scenario parameters can influence EDV deployment—even to a most extreme scenario of adoption—this EDV deployment does not in turn produce a discernible effect on total system-wide emissions. There are three reasons for this lack of observed effect, they concluded: (1) at present the overall share of emissions from the LDV sector is only 20% of US CO2 emissions; (2) EDV charging can still produce comparable emissions to conventional vehicles depending on the grid mix; and (3) the effect of other sectors on emissions is significant.

EDVs offer three key benefits over competing vehicle technologies: (1) reduced consumption of petroleum-based fuels, (2) lower refueling infrastructure costs compared to alternatives such as H2 and compressed natural gas, and (3) a shift in energy production from vehicles to the electricity grid, where emissions from large, centralized facilities are cheaper and easier to control. While previous work has applied different methodologies and models to quantify the environmental benefits of EDVs, several consistent insights have emerged.

First, HEVs produce less emissions than conventional vehicles. Second, PHEVs with smaller battery packs are more likely to deliver emissions benefits and reduced gasoline consumption at lower lifetime cost compared to those with large battery packs in the short term. Third, significant emissions benefits, particularly from vehicles with large battery packs, only begin to accrue with clean electricity. Fourth, CO2 prices as high as 100 $/t do not provide sufficient incentive for vehicle electrification.

While these studies (along with others) have made significant contributions to the literature, they only consider a single point in time or employ sector-specific models or calculations that ignore the interaction of EDVs with the rest of the energy system over time. Recent analyses based on energy system models mainly focus on CO2 emissions and have been run with a limited set of scenarios, which make it difficult to draw insight specific to EDVs.

This paper employs an energy system model to meet the following objectives: (1) identify the conditions under which EDVs achieve high market penetration in the U.S. light duty vehicle (LDV) sector through 2050 and (2) to quantify the system-wide changes in CO2, SO2, and NOx emissions at the national level.

—Babaee et al.

The researchers used a model consisting of two components: The Integrated MARKAL-EFOM System (TIMES), which serves as a generic energy optimization framework and operates on the National US TIMES Data set (NUSTD), a TIMES-compatible data set constructed specifically for this analysis. TIMES is a bottom-up, technology-rich energy system model, which represents an energy system as a network of technologies linked together via flows of energy commodities. TIMES performs linear optimization to identify the least-cost way to satisfy end-use demands, subject to user-imposed constraints such as emissions limits and maximum growth rates on technology capacity.

In their analysis, the authors examined the effect of 5 factors on EDV deployment: crude oil and natural gas prices; a federal CO2 policy; a federal renewable portfolio standard (RPS); and EDV battery cost.

Assumed values associated with each factor were blended to create the large set of 108 scenarios that capture a wide range of potential outcomes. Given the highly uncertain role of consumer choice in future vehicle adoption, they noted, their analysis focused on the economic and environmental performance of EDVs assuming minimal behavioral barriers to vehicle adoption. “Strong and persistent reluctance on the part of consumers to adopt EDVs will dampen or eliminate the EDV-related effects presented here,” they cautioned.

Across all the scenarios, the total EDV deployment ranges from 0−42% of the LDV market with an average value of 24%—a figure broadly consistent with other projections of EDV market development.

  • No EDV deployment occurs with high battery costs, low oil prices, and no CO2 policy. At least 1 of these 3 scenario assumptions must change in order for EDVs to achieve some level of market penetration in 2050.

  • As scenario parameters shift to values more favorable to EDVs—i.e., higher oil prices, a CO2 policy, lower battery cost—the median market shares increase. The maximum EDV market penetration is 16% with the low oil price assumption versus 42% with reference or high oil prices. Similarly, high and reference battery costs limit EDV penetration to a maximum of 34% and 37%, respectively, whereas low battery costs enable the maximum market penetration of 42%. The maximum EDV market share is 42% because EDV deployment is largely limited to the compact and full-size vehicle classes, due to the higher cost of electrification of larger vehicles.

  • The CO2 cap results in marginal CO2 prices of 37−125 $/tCO2, which with other conditions held equal, only increase EDV deployment by approximately 3%. This result is also consistent with other studies demonstrating that CO2 prices less than 100 $/tCO2 have little effect on EDV adoption.

Finding that oil price and battery cost had the largest effect on EDV deployment, they varied these scenario parameters while holding the others constant the better to isolate the effect of EDV deployment on emissions. The high EDV deployment scenario assumes high oil prices and low battery cost, while the low deployment scenario assumes low oil prices and high battery cost. All four scenarios assume reference case natural gas prices and no RPS. They found that, without the CO2 cap, there is no change in electric sector SO2 and NOx emissions because the air pollution constraints remain binding.

Further, the system-wide net decrease in SO2 and NOx (approximately 3% for each) is largely unrelated to EDV deployment: higher oil prices lead to fuel switching in the fuel supply, heavy duty vehicle (HDV), and end-use sectors. Also without the CO2 cap, high EDV deployment creates a 21% reduction in LDV CO2 emissions but a 13% increase in electric sector CO2 emissions.

Accounting for additional changes across other sectors, the system-wide effect of high EDV deployment is a slight 0.9% decrease in total CO2 in 2050.

…it is not enough to simply incentivize the purchase of EDVs and wait for emissions benefits to accrue. The emissions benefits—if any—will depend on a broad set of future conditions. Therefore, public policies that target EDV deployment should be formulated, reviewed, and revised with careful attention paid to evolving changes to the broader energy system over time. If the primary objective is to reduce emissions, policy makers should focus on implementing targeted emissions policy rather than the promotion of specific technologies or fuels. Among the scenario variables tested, the CO2 cap produced the largest and most consistent drop in CO2, SO2, and NOx emissions. Although the observed marginal CO2 prices do not drive significant EDV deployment, the results indicate that EDVs can help lower the marginal price of CO2, particularly if scenario variables favorable to EDVs (high oil prices, low battery cost) prevail.

In the absence of a CO2 policy, the promotion of clean electricity can provide direct emissions reductions and also lower the emissions footprint from vehicle charging. The new EPA proposed carbon pollution standard and the forth-coming proposed rule on existing coal-fired power (due out in 2014) could have a significant impact on national emissions and eliminate some of the potential emissions increases associated with vehicle charging. Finally, other alternative vehicles are worth a mention. First, compressed natural gas (CNG) vehicles are not cost-effective in any scenario, including those with low natural gas prices, because low CNG prices are not enough to overcome the higher investment costs. Second, the model deploys diesel and diesel hybrids in many scenarios, which may be a cost-effective way to reduce CO2 emissions given their higher efficiency compared to conventional gasoline vehicles.

—Babaee et al.

Resources

  • Samaneh Babaee, Ajay S. Nagpure, and Joseph F. DeCarolis (2014) “How Much Do Electric Drive Vehicles Matter to Future U.S. Emissions?” Environmental Science & Technology doi: 10.1021/es4045677

Comments

Davemart

Sorry for the late reply.
Computer hassles, amongst other things.

Its clear from the information given that compression losses are higher than I had thought for hydrogen, perhaps of the order of 15%

I had a good look, and simply could not get truly comparable figures for natural gas compression.
There are figures in plenty about for both, but they are all all over the shop, down to 2% on Wiki for hydrogen compression to 700 bar!

Similarly with NG, the figures vary wildly, let alone trying to find figures compiled on the same basis as the ones for hydrogen.

I am giving it a WAG of 5% at the moment, so it is clear that compression losses are less.

However, when you say:
'It's just that if the hydrogen car uses natural gas, its more apples-to-apples to compare to a natural gas hybrid.'

That is several steps too far!

There ain't no NG hybrids, and for very good reason.
Although the way they compress is different, the main reason why NG costs less in energy than hydrogen to compress is that it is compressed far less.
That is why tanks for NG are much larger than for hydrogen.

Since natural gas is a cheaper fuel than petrol anyway, there is no way that another engine, an electric one, a pretty substantial battery and so on are going to be engineered into a NG car.

So you are comparing it with a car which doesn't exist and likely won't.

Due to the smaller tank an LNG hybrid might be possible, but I am simply not going there in this thread.

In practical terms, as opposed to theoretical terms about energy, for a garage although the compression ratios may be different, a compressor is still needed for NG or hydrogen, and so is a high pressure tank.

That means that it is not so very different to deal with NG or hydrogen, and the costs for the garage are not wildly different.

So a totally clean burning fuel which is still knocking on for twice as energy efficient if it ain't quite there is attractive.

My main comparison remains against petrol cars though, where it certainly is twice as efficient.

That is because that is what 95% or so of cars actually run on.

Again, if we are talking purely about energetics, then a hybrid version will be more efficient on petrol use.
However fuel cell cars are nothing like as efficient as they can become anyway, they have plenty of headroom.

And in practical terms, in a hybrid you are paying for a second engine, a high temperature exhaust and so on.
The fuel cell car is not just more efficient, but more elegant.

Anyway, thanks for the challenge of your close analysis.

I think we have come to some sort of reasonable consensus on the energetics, and fuel cell cars come out well enough in my view.

Engineer-Poet

A.C.R.:  Compression work is not linear with pressure, it's closer to logarithmic.

CE88:  Battery swap is a possibility for big rigs, so even if the cells take 24 hours to charge they would still be quite usable (and the grid-management potential in the charging cycle is immense).  GCC ran the piece which led me to this thing on PhysOrg:
http://phys.org/news/2013-09-molten-air-battery-storage-capacity-highest.html

Davemart

@EP:
Even for big rigs it is difficult to make battery swaps work without standardised batteries.
Batteries are expensive enough already, and having spares make things worse.
Their horrific energy to weight ratios would reduce load anyway, which is anathema to freighting.

Fuel cells, although better, don't work for heavy freighting either.

Volvo are looking at biofuels for that reason for the application.

CheeseEater88

Working on cars for a living makes me think Tesla's battery swap location is kind of futile, 1 year or so with road salt anything can happen, and especially when the thing is done autonomously. Torque to spec, even as precisely done with a computer could yield some problems, corrosion, seized parts, damaged or missing parts (even if it is shielded...people manage to hit things in the strangest of places)


Over the road trucks, do millions of miles, lots are owned privately. Battery swapping while a good thing, might not be fiscally possible. Im not saying it cant be done, I actually think that there should be the ability, but the kicker is no matter how you slice it the battery will be a large expense and subject to faults. So a truck with limitless battery swaps for the life of the cab would be great, but initial prices would be prohibitive to the small owners. They could however come up with a pricing / lease system and have it be fruitful. I think tesla is shooting themselves in the foot with free battery swaps.

Molten batteries do sound great for trains, just an oil change is extremely expensive(4000 gallons of oil iirc), or just to fill it. The rail system although efficient in energy per ton per mile or how ever you want to say it, there is not a great network of rails so there is a lot of waiting. Over head charging could be done too and that could be easily standardized.Or the possiblility of battery cars as hybrid slaves or something.

I would also on a semi like to see a FC onboard. Maybe just for emergencies, accessories, and cabin heat/ battery optimization. A 110 outlet wont be much help. But a 50-100KW FC may, and you could down size the battery substantially. You still could have a plug in. If the battery alone could get you 80% of the way, and you ad regen braking and a generator to the mix. You could run nearly non stop,( and fast charge when you do)
There is plenty of space for 150 gallons of batteries, electronics, and probably more than enough for a FC
Each truck carries 2 150 gallon tanks. They have massive 14 liter engines with twin charging. and massive transmissions. with no tanks, no engine, and possible no transmission(motor in wheel design). The electronics wouldn't be in a much larger package than the size of the Tesla,( I doubt to see much higher voltages). and the battery could be modular or just a large giant piece. Here the FC really makes sense because $50K (assuming 100kw)at todays production level is still small compared to the powertrain in a Diesel truck


and in reply after I typed all of this to davemart.
I do think that Plug-inFCs will exist in heavy trucking. Its expensive, but so is diesel, and having something like a 70% uptime, at highway speeds could make it very lucrative. I also think that curb weight wont be that affected. There are lots of components that can be tossed to the wayside in such a system. Transmissions, the engine and dressings, not to mention drive axels. I think it will be close to a wash. Even with 100gallons of molten electrolyte. (300 gallons of diesel weighs a bit too)

A.C. R.

"There ain't no NG hybrids, and for very good reason."

There ain't no hydrogen fuel cell hybrids either, for very good reason. Cost, efficiency, safety, longevity, practicality, lack of refuelling infrastructure, and so forth. Very similar reasons to why there "aint" no NG hybrids.

Interesting, don't you think?

A.C. R.

"Compression work is not linear with pressure, it's closer to logarithmic."

I never said it's linear. Simply that the theoretical energy requirements aren't met anywhere near. More like 8x the actual requirement over theoretical efficiency.

For now we can say that natural gas as CNG cars and hydrogen @ 700 bar have very very roughly similar compressive losses.

A.C. R.

"I think we have come to some sort of reasonable consensus on the energetics, and fuel cell cars come out well enough in my view."

Yes, its almost as good as you said it would be, interestingly.

It was an epiphany for me just how big the losses are for gaseous fuels (both hydrogen and natural gas). It really makes you value liquid fuels.

Davemart

ACR:
I find your reasoning strange when you equate the reasons why there are no NG hybrids to fuel cell hybrids.
If you want a reasonable size tank for NG, then it needs compressing more, and bang goes your advantage in compression losses, and you are simply stuck with a less efficient system.

I am not sure why you should value liquids more, unless you are talking of maybe direct methanol fuel cells when we can do them, as the very large efficiency advantage over petrol remains even after compression losses.

A.C. R.

Actually Dave, a 250 bar natural gas tank holds a lot more energy than a 700 bar hydrogen tank. 9 MJ/l vs 5.6 MJ/l according to Wikipedia

http://en.wikipedia.org/wiki/Energy_density

Liquids are much easier to distrubute, for example via fuelling trucks like we do for gasoline and diesel. That's much easier to do than laying down high pressure hydrogen pipelines all over the continent, or build natural gas pipelines of high capacity to each and every fuelling station (in case of the reformer-at-fuelling station option). Hydrogen can be liquefied but its inefficient and only makes sense if the cars use liquid hydrogen too - if I remember correctly all fuel cell car makers are going for compressed hydrogen.

A solid oxide fuel cell running on compressed natural gas seems the best of both worlds (between CNG cars and hydrogen cars). May be difficult for mobile application though. It'd also take several minutes to get hot, consumer drivers will probably not like that.

A.C. R.

"I find your reasoning strange when you equate the reasons why there are no NG hybrids to fuel cell hybrids."

Why is it strange? Hydrogen and natural gas are both inconvenient gaseous fuels so they suffer from compressive losses, infrastructure needs, and cost. Hybrids cost more than non-hybrids. It is clearly not worth it for natural gas CNG cars since the fuel is cheap. So one has to wonder about the fuel cell hybrid where the fuel cell costs more than the ICE and then adds another expensive component, the hybrid drivetrain. If you're competing against priuses etc. then that is going to be very tough competition for fuel cell hybrid cars. The price would have to be lower than a prius for this to really take off exponentially.

A.C. R.

This graph has well to wheel CO2 emissions per mile for different vehicles:

http://www1.eere.energy.gov/vehiclesandfuels/images/facts/fotw686.gif

Natural gas battery hybrid electric: 185 grams CO2/mile.
Fuel cell battery hybrid electric: 200 grams CO2/mile.

This indicates that the fuel cell on reformed natural gas uses more natural gas per mile than the natural gas hybrid electric (by the way, we were wrong; these cars do exist).

CheeseEater88

ACR,
The biggest motivator in industry and consumer markets is dollar efficiency. I know of one fleet personally making the switch to CNG F150s, It doubles the range of their trucks, and it allows for them to fill up insanely cheep.
I would if given the chance, buy a CNG vehicle, or a dual fuel vehicle. I don't need an F150 per se, but being in my brothers, its hard not to like it.

I was thinking more of an expedition or explorer(if they could ever make them) for myself as I need a lotta people mover in the near future plan on settling down in a few years, and I plan on being a single car family. So fuel costs, coupled with capability is important. I want to avoid monthly payments on a second car both insurance and for the loan.

I keep cars for a long time(~10 years or so), I can't afford buyers remorse either. If in 5 years I find battery electric SUVs that could seat seven going 300 winter miles for $50-60K I would make that jump. If FC vehicles are in that range I'll make that jump first because of the nature of my lifestyle.

I drive cross country 2x a year, some days ill have to drive 150miles just to get to an actual town and back.

I know BEVs are cheaper to 'fuel' than FCs, but having the ability to leave at a moments notice because of an emergency or other unplanned situation and not have to worry about making it without stopping for extended periods of time.

Jus7tme

Well, this is yet another well-researched paper that shows that EV, natgas and hydrogen are all WORSE in terms of CO2/mile and efficiency than the best hybrid vehicle technology. Exactly what I have been explaining right here for years on end.

@A.C.R., thanks for all your posts in this thread. I have not read them all yet, but what I saw so far was excellent. Thanks for making the effort. It's hard work to counteract and respond to the sheer volume of propaganda and misinformation that is being spread by the EV, natgas/CNG and hydrogen/H2 camps.

Engineer-Poet
it is difficult to make battery swaps work without standardised batteries.

Of course.  There would probably be a standard set of sizes:  100 kWh, 300 kWh, 1000 kWh.  The form factors would be arranged such that vehicles could use more than one, perhaps even 3.  Packing a trio of 1000 kWh batteries would work even for big rigs.

Batteries are expensive enough already, and having spares make things worse.

Molten salts and iron are extremely cheap materials.  High temperatures eliminate the need for exotic catalysts to overcome activation energy.

Their horrific energy to weight ratios would reduce load anyway, which is anathema to freighting.

There you do have a point, but even the iron-salt-air battery holds 1.4 kWh/kg.  3000 kWh would take about 2200 kg, not all that much more than a 500 HP diesel at 3500 lb or so.  The battery would also carry the truck for as much as 2000 miles, replacing at least 200 gallons of diesel.  200 gallons of diesel weighs upwards of 1400 pounds, so the battery-electric system may have an overall lower "mission weight".

Last, the BEV is the only one that can take power from PV, wind, hydro or nuclear without conversion costs or losses.  The potential carbon emissions in use of the BEV are zero.

Davemart

@EP:
Charging the battery gives around a 15% loss for a start, and in the US there is a huge 7% transmission loss, not to mention that getting the wind and sun when you need to power the car is non-trivial and invariably involves losses.

However, I agree that potentially the losses are probably smaller, at least with a sensible energy policy which we show no signs of getting, and only around 100Gw are needed to provide all the electricity for a fleet of BEV cars.

They aren't asking me though, so I stick to trying to assess what is on offer.

The bit I have become convinced of is that at minimum a fuel cell RE in cold climates leads to massive increases in range and utility.

Davemart

S/be '100GW of nuclear plants, around the same as the current fleet again'

Engineer-Poet
Charging the battery gives around a 15% loss for a start, and in the US there is a huge 7% transmission loss

Hardly "huge", either of them.  Eminently tolerable.

getting the wind and sun when you need to power the car

Who said anything about that?  My model is almost all nuclear, with RE in region-specific roles like air conditioning.

only around 100Gw are needed to provide all the electricity for a fleet of BEV cars.

Electric grids need to be de-fossilized, and then there's a heaping buttload of other energy use that ought to be electrified as soon as that's done.  The total is probably around 1000 GW(e) in the USA alone.

Roger Pham

@E-P,
Good point on your analysis for Molten salt Iron battery on HDV. I kinda did the same analysis for compressed H2 and came to the same conclusion as you did. Even though H2 tanks are much heavier than the wt. of diesel fuel and tank, the motor and FC stack are much lighter than a turbo-diesel rig, PLUS a hefty transmission of 12-16 gears. Using electric motor, perhaps a 3-speed gear is all needed, much simpler and lighter.

So, whether battery or H2-FC, long-haul diesel trucking can also benefit from electrification without impacting payload capacity. The H2 tanks will be more bulky than diesel tanks, but there is plenty of space around the cab of the tractor for H2 tank.

The total generation capacity is around 450 GW(e) at 100% load capacity, or 3000 GW of solar or 2000 GW of wind, or ~500 GW of nuclear AND a bunch of electrolyzers to store excess power by making and storing H2, and a bunch of FC-CHP to boost the grid when needed and to heat the room and water.

CheeseEater88

Okay I pounded out some numbers, these are in no way accurate but based on knowledge and comparing mpge to mpg, I am able to get some estimates. For example a pickup truck during towing would get about 7-11mpg on conventional ice. I compared the 38kwh/100 miles of the volt and settled on 144kwh/100 miles on the truck by comparing the gas operation to the electric operation, obviously its not an accurate comparison but it allows a ballpark answer.

So, to have a pickup go 300 miles towing using that number (which I think is low). It would need a 430KwH pack. Batteries would need to be priced at or around $50/kwh for cost parity on purchase price. As for price parity overall cost of owner ship, I have no idea.

As for tractor trailers I would wager they would approach 367kwh/100 miles, based on a 3mpg guess, (which is high, which really lowballs the other guess)
My estimates for strictly battery operation we would need at least 3000kwhs(yay we agree) of on hand storage.

Ideally you would want to allow for winter consumption, hill climbing, the odd traffic jam/ stop and go, and excess capacity to combat the loses over time... maybe 3500-4000kwh would be more ideal.
Charging would be a nightmare, a swap center would need several MWs going to it. If it were popular it would consume like a small city. Which if parked next to a windfarm(or several, could be advantageous for grid/power efficiencies.

But still we are talking about million dollar trucks 1.7million(for just batteries)4000kwhrs at $416/kwh, $800k $200/kwh, $200K at $50/kwh. Though if it were over the cost of ownership, maybe cost would be cheaper in the long run.

I envision a 750-1000kwh battery(swappable), and a FC range extender with about 275-400KW generating power. It would allow for all electric operation on local deliveries over the course of a day, and for over the road it would allow sufficient generation to go indefinitely, even in times where generation might be slower than consumption. There also wouldn't be as massive of a grid strain from BEV only trucks.

CheeseEater88

a $20,000 fuel stack and probably $50K-70K in other FC components could save $500k off of the purchase price@$200/kwh or more if its higher. Which would lead to higher adoption rates, more electrification in the transportation sector, (some maybe driven in an all electric state most of the time even)... It would be comparable to a phev.

Engineer-Poet

Current semi rigs run about 6-7 MPG, and the hyper-aerodynamic tractor featured here a week or so ago claimed upwards of 13 MPG.  At 10 MPG and 45% thermal efficiency, it works out to 1.85 kWh/mile.

The iron-molten salt-air battery recently invented holds 10 kWh per liter, so a liter would propel the semi about 5.4 miles, about 20 miles per gallon of battery—less volume than diesel fuel requires!  If this ever gets packaged for mobile, the OTR diesel is a goner.

CheeseEater88

I messed up on the 3 for the OTR truck, but I think 5-6 is more like it having researched it better(5 under heavy load, 6 is common when I browsed the trucker forums, but there we a few mentioning low 4s, and others getting 8s and sevens) I do think 10 is unrealistic, especially when you think about geography and other common place inconveniences.
So, not using the miracle truck, what is the efficiency comparison of 5 or 6mpg diesel to electric miles? So around 3.02-3.6KwH/mile? Even if we used 8mpg it would be around 2.2KwH/mile...

I just want to try and cover the bases, using optimal numbers to set a minimum is kind of gaudy, an average or slightly less than average would envelope almost all scenarios; picking ideal number excludes the masses, no one would want to put themselves at that sort of risk.

I still would like to use 3.5KwH/mile for easy math and that its representative of most truckers, which also allows for less than ideal scenarios, hills, traffic, winter, elevation, and heavy loads.
I hope that these new batteries are >10kwh per liter,that they have innumerable charges, that they flow an insane amount of current both into and out of the battery, and that they cost <$50/Kwh because that's probably what it is going to take to get OTR trucks to switch.

I want to make a correction, and say that 3MwHs would be enough for an over the road trucker in the USA. I used 4MwH in the cost before.

I am not saying it would be hard to fit or anything, its still practical (3600 / 3.79) / 10 = 94.9868074gals... even when 20% over capacity... that and you figure most of the powertrain is absent, leaving a large area to place the battery.
Cost is the main issue, if this battery can come in at less than $100/kwh or better yet in the $50 range cars/light trucks will switch almost instantaneously, (I would iff I could get a 600mile range, id be on it like white on rice)

I never had faith in Li batteries, molten batteries have much more promise.

I feel that FC-Plugin-Electric-Hybrid Trucks are going to be the thing though, Fuel Cells are at a system cost below $47/kw at mass production, or about $84/kw at 10,000 units. so $14,100-25,200 for a system to power an OTR Truck. Meaning you could get by with 500-1000KwHs on reserve, loosing a huge chunk of battery (and cost)and allowing for a fast refill, measured in minutes not hours.

Engineer-Poet
what is the efficiency comparison of 5 or 6mpg diesel to electric miles? So around 3.02-3.6KwH/mile?

Figure 140,000 BTU per gallon of diesel fuel.
1 BTU = 1054.4 J
1 kWh = 3.6e6 J
Medium-speed diesels have efficiencies in the forties.  Pick a number, or look up the BSFC of a likely candidate engine and use that.

5 MPG = 28,000 BTU/mi of fuel.  At 45% BTE, 12,600 BTU/mi at the crankshaft.  You convert to kWH.

they cost <$50/Kwh because that's probably what it is going to take to get OTR trucks to switch.

Figure cost of diesel is $4 for 140kBTU of fuel, about 22¢/kWh at 45% efficiency.  Off-peak grid power costs something less than 10¢/kWh most places.  If the battery lasts as little as ~1000 cycles and 3 years, you've got a 12¢/kWh difference to arbitrage over a throughput of 1000 kWh, or $120 per kWh of capacity.  That's the savings, the price could be a substantial fraction of that (up to maybe $75-$100/kWh); longer-lived batteries would be worth more.  The price volatility of electricity is a lot less than petroleum also.

Some cities and states would simply mandate electric traction for air quality reasons.

Cost is the main issue

Always has been, always will be.

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