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MIT Study Compares 2030 Electric Propulsion Systems; Conventional Hybrids, Fuel Cell, Battery and Plug-in Hybrid Electric Vehicles Offer Comparable GHG Reductions

Overview of projected greenhouse gas and fuel consumption outcomes for different propulsion systems in 2030 vehicles. Click to enlarge.

Electric propulsion systems, including gasoline hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV), fuel cell vehicles (FCV) and battery vehicles (BEV), can, with projected evolution of the supporting technologies, “reduce or eliminate the transport sector’s reliance on petroleum,” according to a study done at MIT by Matthew Kromer and Professor John Heywood.

However, the study also concludes that continued use of fossil fuels without effective carbon capture and sequestration for producing electricity and hydrogen constrain the greenhouse gas (GHG) and energy reductions of all the different forms of electric propulsion to about 60% below that of present day technology. In other words, without cleaner power pathways, PHEVs, BEVs and FCVs are not projected to offer much of a greater reduction in GHG than an HEV, and in many cases, the GHG profile is worse.

The study, presented at the SAE 2008 World Congress in Detroit, quantifies the potential of electric propulsion systems to reduce petroleum use and greenhouse gas emissions in 2030 US light duty vehicles. The paper is a follow-on to a study presented last year that assessed the potential improvement of more conventional automotive powertrain technologies 25 years into the future. (Earlier post.)

For the purpose of the study, the authors used a 2006 2.5L Toyota Camry as the basis for the future propulsion systems. For consistency across vehicle platforms, they held vehicle performance and size constant at present-day levels. Holding the parameters constant, they noted, is at odds with historical trends, which have shown a steady increase in size and performance over the last 25 years. However, by keeping the characteristics at current levels, they could quantify efficiency gains enabled by the technological progress.

The future vehicles do include a number of evolutionary, non-powertrain improvements which are applied consistently across different vehicle technologies, including improved aerodynamics, reduced rolling resistances and some weight reduction.

Projected Characteristics for PHEV Battery Packs
Range[mi]10 30 60
Road Load [Wh/mi] 183 186 193
Energy [kWh] 3.6 8.2 16.5
Pwr/Energy [W/Wh] 13.5 5.5 2.9
Spec. Energy [Wh/kg] 110 135 140
Spec. Power [W/kg] 1500 750 400
Battery Mass [kg] 32 60 120
Specific Cost [$/kWh] 420 320 270
Battery Cost [$] 1450 2700 4500

They assumed the use of lithium-ion battery packs with several adjustments to present-day performance characteristics: the ability to maintain rate capability at high depth-of-discharge and evolutionary improvements in battery specific power and specific energy.

They assumed that specific energy improves by a factor of 1.5 over current Li-ion packs (a rate of about 2% per year) for both high-power and high-energy batteries.

To characterize the impact of the uncertainty over future power generation pathways, the authors considered three different generation scenarios: US national average grid mix, 100% coal, and 100% natural gas. Calculations were based on the projections from the EIA Long-Term Energy Outlook for 2030 and include 9% transmission and distribution losses, and 10% charging losses.

The simulation results showed that advanced technology vehicles offer a number of paths to reduce petroleum consumption: the hybrid electric vehicle (HEV) in 2030 offers a 63% reduction over the 2006 baseline vehicle and a 43% reduction compared to a 2030 gasoline vehicle.

The plug-in hybrids offer even greater reductions, with the magnitude dependent on the all-electric range of the PHEV. A 2030 PHEV-30 (30 mile electric range) offers an 81% reduction in petroleum consumption compared to the 2006 baseline vehicle, and a 71% reduction compared to the 2030 conventional gasoline vehicle. The PHEV-60 takes those percentages up to 88% and 81%, respectively.

However, they noted:

Reducing vehicle energy use and GHG-emissions beyond the level offered by the gasoline hybrid presents a much greater challenge. Under the assumed fuel production pathways, the hybrid, plug-in hybrid, and fuel-cell vehicle each offer a 40-45% [GHG figure] lower than the 2030 NA-SI baseline. These results suggest that without an effective effort to develop cleaner fuel pathways, a transition to alternative fuel powertrains does not deliver a significant CO2 benefit beyond that offered by the gasoline hybrid vehicle.




It depends on where your electricity comes from.

If is still mainly coal, you get a lot of GHG.
However, if you swap out coal for Nuke or Solar and or wind and gas, you could get a lot of the CO2 out of the system.
One advantage of a larger battery vehicle is that it could wait longer to recharge, and could then recharge when there is an excess of renewables.

Thus, even though a 30 mile electric range might be enough, if you could hold on for a day or two, it would increase the chance of charging from wind or solar.

Not only could the larger battery buy range, it could also buy time, and increase the chance of a "clean" recharge.


The larger battery would also get you longer battery life since you won't be deep cycling the battery as much.

Healthy Breaze

These studies seem like such a "Duh" kind of excercise, but I guess the real reason is to make it clear that just switching to Hydrogen as a storage medium doesn't have any positive effect on GHG by itself.

However, I wonder about electric. I thought all industrial scale power plants had higher conversion efficiency than ICE, and that even with transmission losses, it was still very possible to come out using less fossil fuels to travel a given distance. Perhaps this study says that's not so, or perhaps it just has to include the stupid approaches to, to show the continuum.

Near Las Vegas, Ausra has built a factory for annually making linear fresnel solar thermal power plant modules that can generate 700 Megawatts at peak. That's a bout 350,000 households/year worth at (they think) between 16 and 10 cents per kilowatt hour. It seems like solar thermal has to be a huge part of the answer for transportation energy.

Harvey D

Electricity is not produced with coal everywhere.

For example, in Canada, the average is only 19% with coal, 58% Hydro, 12% Nuclear, 8% NG, 4% Oil, 2% Wind and Biomass. It varies even more if you consider each local or provincial grid: Quebec is 96% Hydro, Manitoba is 91% Hydro, BC is about 80% Hydro etc.

Depending where you live in Canada, PHEVs and specially BEVs would drastically reduce GHG over current ICE vehicles. This would be specially true if we could downside the current Tar Sands operations instead of multiplying them. With enough vehicle electrification, Alberta's extremely high per capita GHG (mostly from or for Tar Sands operations) may be reduced (3-fold) to the average Canadian level, instead of going up to about 6 times the Canadian average by 2020.

Many other countries get the majority of their electricity from cleaner sources than coal. Wind, Sun and specially Nuclear energy could reduce reliance on coal, even in USA.


Less than 40% of the world electricity production is based on coal. Over 20% is renewable and 14% is nuclear and the rest is mostly electricity generated from Methane (lower CO2 per energy unit than gasoline) with a thermal efficiency of nearly 60%.

Why would the same vehicle running on gasoline (relatively inefficient IC) generate less CO2 than one running on electricity?

Also why does a fuel cell vehicle produce less CO2 than the electric vehicle even though fuel cells are significantly less efficient and hydrogen is supposedly produced from the same grid (also with lower efficiency)? And if it was produced from fossil fuels where did the Carbon go?

Also, since 2004 the entire renewable power generating capacity doubled worldwide. Does MIT suppose that this enormous growth will stop from now on?


This study uses quite pessimistic assumptions, including: a 2% annual increase in energy density for batteries, minimal uptake of solar, wind power or other renewables and no improvement in battery cycle life, that are not justifiable. Less pessimistic, but still conservative, assumptions would drastically alter the report's conclusions.

For example, based on the last 30 years, the cost per watt of solar PV modules has decreased at a rate of 7.5% per year and unit sales (in watts) have increased by 30% per year. In California grid parity at the retail level, i.e., your home or business, will probably occur in 2015 (followed by increasing grid disparity). Grid parity will occur in different areas of the US depending on sunshine levels and electricity rates - it has already happened in Hawaii. So what is the justification for only considering "three different generation scenarios: US national average grid mix, 100% coal, and 100% natural gas" in 2030?


Arg... The bullshit keeps flowing.


Alright to start off with

They are comparing:
1. Hybrid on Gasoline
2. PHEV entirely! on Coal
3. Fuel Cell on Natural Gas

That right there is completely false comparison.
* Only half our grid is coal
* and if you compared PHEV on natural gas, to a fuel cell on natural gas, the fuel cell would be dirtier.


Second off John Heywood is pretty much the only other person (Besides Michael Wang) to publish a paper saying that corn ethanol isn't a horrible idea from an emissions perspective.

And that paper is pretty pathetic.

As for the second author, he's from TIAX consulting. And what they do is pretty much take Michael Wang's GREET model, play with the variables, and then write up a long report about it.


So pretty much it's two authors which are completely estranged from the rest of the peer reviewed world, and make gigantic assumptions that hold no basis in reality.

And whats worse, this paper they are touting Isn't Even Peer Reviewed! It's a damned white paper.

(And it's primarily based on Michael Wang's GREET Model, which also isn't peer reviewed!!!)


Absolutely disgusting.


Now for instance, lets compare

1. A Toyota Prius on gasoline
2. A Honda FCX on steam reformed natural gas
3. A Tesla Roadster on natural gas electricity

Notice any difference?


Wups, wrong chart.


[[Might as well go for the gold in spammage.]]

This chart works a little bit better in framing the issue at hand.


In short, second and third generation biofuels used in ICE's beat all these electric propulsion technologies hands down, given the fact that you can produce both electricity and liquid fuels (co-generation), as well as store char fractions in soils.

No cost-picture, which is a pity, because that's ultimately the biggest problem with electric concepts. They are prohibitively expensive. It may take 50 years before electric transport becomes a reality in the huge developing world, where most of the growth in transport will occur.

Ben Kaun

With respect to plug-ins, the GHG emissions from a coal plant are going to be released whether or not the plug-in is there, because it's baseload power that the utilities don't want to ramp up and down. Therefore, if you fill the battery at night, it's almost free in terms of $$ cost and effective emissions. In addition, grid-interactive plug-ins can add capacitance to the grid during the choppy peak power afternoon hours, effectively reducing the necessary "spinning capacity" need to avoid brown-out. This will also reduce GHG emissions. I doubt this was taken into account, which I believe would make the numbers better looking for PHEV/BEV. Anyone know how much?


In short, second and third generation biofuels used in ICE's beat all these electric propulsion technologies hands down, given the fact that you can produce both electricity and liquid fuels (co-generation), as well as store char fractions in soils.

In short, incinerating biomass is an amazingly inefficient thermodynamic process, which involves no storage of carbon.

It's just a shell game, which in the process which also creates CH4 and N2O which is tens to hundreds of times more potent than CO2.


And even if you could make it work with extensive burying of carbon, I'd love to see you try to do it cheaper than electricity.

Last I checked, if we wanted to sequester even a fraction of existing coal plants CO2 emissions, it would take a liquid-CO2 infrastructure equal to the size of our existing petroleum infrastructure.

Now imagine trying to do something like that with something that's not nearly as dense or portable as a liquid.

Small scale? Maybe.
Large scale, delusions of graduer, where the methods are more important than the goal itself.

But as you've already made emphatically clear Jonas, the Method is more important than the Goal. To you atleast.

If anything, I got a pretty good laugh out of this statement:
"Jonas: Unlike you, I'm not biased towards any particular technology or policy"



Biofuels are a part of the solution but they are not a panacea because of the land area required - water area in the case of algae.

The cost issue has been analyzed by the Electric Power Research Institute in a 2005 report that compares the life cycle costs of a conventional vehicle and an equivalent PHEV. With assumptions of of $1.75 per gallon gasoline, $0.05 per kWh off-peak electricity, 3% inflation, 8% discount rate, and 10-year 117,000-mile vehicle life, the life cycle cost would be equal for a battery cost $475 per kWh.


Even with the most beautiful dreams of charging the BEVs CO2 free during off peak hours, the fact is that going electric will increase the consumption of electricity. This increase could be up to 50%.

Now, the question is how is this increase covered? The only realistic options are natural gas, coal and nuclear. And I'm not too sure about the natural gas part... It is too expensive.

Same goes for Canada or any other country. Maybe Island has a lot of un built hydro power...

So, unless we build A LOT more nuclear, we're talking 100% coal.


"Biofuels are a part of the solution but they are not a panacea because of the land area required - water area in the case of algae."

Sorry, what land area are we talking about with second gen biofuels?

And what water area? Algal fuel prototypes are in progress on desert land with recycled water. Even in the case of salt water cultivation, eco-system management will address O2 and bloom issues.

Dan A

Fuel cells would be more efficent because it's produced chemically from natural gas, not electrically. It's much more efficent to turn natural gas (or coal for that matter) directly into hydrogen than it is to use them to produce electricity with them and then electrolyze water.

One of the downsides of the mass adoption of PHEVs/BEVs is that yes, they use baseload power--meaning more coal or nukes--renewables and nat gas aren't baseload (or at least they shouldn't be). Seeing that nuclear is probably going down (even the most aggressive adoption proposals keeps it at the same proportion of electricity as it does now, any less and it gets smaller) and that renewables will be lucky to make up for the decline in nuclear, it doesn't seem like coal is going away for the forseeable future.

As I see it, HEV with diesel or flex fuel using algae biodiesl/cellulosic ethanol (one of the companies are bound to get it right) and PHEVs using the same backup will be it.

What would be interesting would be using desert areas with solar thermal to produce electricty and do desalination (they do it anyway) producing fresh water for algae ponds with a coal gasification/nat gas plant providing CO2 for the algae in an integrated energy complex.


Consider cellulosic energy crops (switchgrass, poplar) Third generation - since waste to syngas is already online.


Dan A,

Integrated Solar Combined Cycle looks interesting but your twist with the algal component is better still. There appears to be some growing movement in this area and in light of increased grid demand (over twenty years) I think we all would be more secure with solar thermal combinations than straight coal.

The one 345 MW SEGS station in Mojave produces 90% of world's solar thermal electricity. Though the land use and 400,000 parabolas is a challenge - some of the combined systems look plausible and even profitable (given the downside of burning coal).


Helen: 100% coal? ... that's just plain ol' BS.

Dan: where do you get the idea that EV charging has to come from base load? Intelligent charging and V2G puts any source into play at some level.

P.S. Hydrogen into fuel cells from rectified NG and EVs powered from NG have almost identical efficiencies (with the fuel cell having a ridiculous price)
source - Argonne national labs


The only realistic options are natural gas, coal and nuclear.


This is BS.

How do explain that more renewable power than nuclear power is produced worldwide?

How do explain that the EU installed 8854 MW of Windpower last year - more than any other power generating technology in 2007? And at the same time got rid of -1203 MW nuclear power?

And btw, Germany installed over 1300 MW of photovoltaics in 2007.


Helen ,
Yes I agree it is total BS , when you give people the choice of
buying a BEV or a PHEV , their minds automatically look around for
other ways of providing the electricity required to run the thing , and
solar generation is the natural solution .
Here in northern italy , which is about the same latitude as Maine
a guy next door to me has installed 27 panels on his roof , at the cost
of about 30000 euro , and this year he will of generated over 6000 Kwh
from these panels which he feeds back into the grid , and guess what?
yep , he´s now in the market to buy a BEV to do all the local trips.

This is exactly what the powers that be are desperately trying to
avoid , it upsets their status quo , and this is why all these so -called
scientific studies are so blatantly loaded in favour of ICE´s and the use
of hydrogen . Its the same here in europe , in fact probably more so
seeing as most of our blood-sucking governments survive from the
revenue from road fuels !


In any case: biofuel critics commit "crimes against humanity". Says Lula.

Discarding biofuel would be 'crime against humanity': Lula

I'm no longer doing this debate, it's become too rethorical and full of confusion.

John Taylor

comments are over, page closed, Jonas link has taken over the rest of the page ... perhaps if the thing is fixed we can consider if Electric cars are “dirty” because they might get their electricity from coal fired plants, while hydrogen is “clean” .... I presume the hydrogen just appears by magic and does not require electrolysis using electricity from those same coal fired sources.


The whole argument for fuel cells in this paper seems to be that electric cars must be powered by coal, and fuel cells get to be powered by natural gas.

The question being, if you have the natural gas, why don't you use it to power the electric cars?

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