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T&E concludes that diesel cars emit more CO2 on a full lifecycle basis than gasoline cars

18 September 2017

A new analysis by the NGO Transport & Environment (T&E) concludes that diesel cars emit more CO2 than equivalent cars on a full lifecycle basis—i.e., accounting for the emissions generated during production of the vehicle and the fuel.

According to the T&E analysis, an average diesel car produces emits 3.65 tonnes more CO2 than an equivalent gasoline car over its lifetime due to a more energy-intensive refining of the diesel fuel; more materials required in the production of heavier and more complex engines; higher emissions from biodiesel blended in the diesel fuel; and longer mileage because fuel is cheaper.


To derive the emissions figure, T&E said that it made a number of assumptions for their calculations:

  • The average gasoline lifetime driving distance of 175,000 km (108,740 miles) is taken as the starting point.

  • The average diesel car is driven longer, however, only 4% of this is due to the lower fuel price (rebound effect). T&E adds an additional 7000 km (4,350 miles) to the diesel lifetime distance to account for this.

  • T&E used the latest real-world fuel consumption figures for diesel and gasoline: 6.3 l/100 km (37.3 mpg US) and 7.1 l/100 km (33.1 mpg US), respectively.

  • To account for biodiesel effects, T&E assumed a conservative estimate of 5% biodiesel content. The composition of the biodiesel itself uses the average shares of rapeseed oil (48%), palm oil (27%), waste oils (15%), soya oil (5%), tallow & grease (4%), etc.

  • Similarly, a 5% bio-blend is assumed in gasoline for consistency, using the EU average shares taken from ePure: corn (38%), wheat (37%), sugars (14%), etc.

  • The carbon intensity of both biodiesel and ethanol is derived by adding ILUC values (the Globiom EC study) to the direct carbon intensity of different feedstocks.

  • Extra manufacturing emissions are taken to be 5% of the average 5 tonnes of CO2.

  • For diesel and gasoline shares of B7 and E95, diesel and gasoline specific densities, energy contents and JRC-derived overall well-to-wheel (WTW) carbon intensity factors are used.

In Europe, the car market is skewed in favor of diesels through regulation and tax policies. Whereas the diesel share in Europe is around 50%, it is a niche product in the rest of the world. Europe buys 7 out of 10 diesel cars and vans sold globally while less than 1% of new vehicles sold in the US are diesel and in China, the world’s largest vehicle market, diesel represents less than 2%.

T&E attributed Europe’s diesel share to three main causes:

  1. Distorted national fuel and vehicle taxes. Diesel fuel is taxed between 10% and 40% less than gasoline in most countries. This “diesel bonus” cost national budgets almost €32 billion in lost tax revenue in 2016 alone.

  2. Unfair EU Euro emission standards that for decades allowed diesel cars to emit more NOx than gasoline cars. This has been exacerbated by the use of obsolete tests (recently updated) and ineffective regulatory oversight.

  3. Biased CO2 regulations that set weaker targets for carmakers producing bigger and heavier diesel vehicles.


Going forward, it is could be more appropriate to compare diesel vehicles with alternative low-emission and zero emission powertrains. The most recent and comprehensive lifecycle analysis in this regard has been undertaken by VUB MOBI… The LCA model includes well-to-tank emissions (raw materials, refining, production including components and assembly, and distribution) and tank-to-wheel emissions (use, as well as maintenance and road infrastructure). The analysis demonstrates that the lifetime CO2 emissions of plug-in hybrids and electric vehicles on different electricity mixes are already substantially lower than comparable diesel vehicles. The benefit will continue to increase in the coming years, as more low-carbon and renewable electricity enters European electricity mixes.

—T&E study

Accounting for production emissions. In addition to highlighting the regulatory and tax policies that have helped to drive diesel market share in Europe, the T&E study also indirectly opens the provocative question of how to account for greenhouse gas emissions during the production phase.

This is emerging as more of a factor in a comprehensive greenhouse gas control policy as the push for lightweighting to reduce on-road fuel consumption is driving the adoption of lighter metals—but metals that also carry with them a higher carbon footprint.

The steel industry, for example, has been making this argument for about 10 years now. As one example, the Steel Market Development Institute (SMDI) claims that the use of AHSS (advanced high-strength steel) reduces a vehicle’s structural weight by as much as 25% and can cut total life cycle CO2 emissions by up to 15% more than any other automotive material. According to SMDI, while the greenhouse gas emissions from the production of steel are in the range of 2.0-2.5 kg CO2e/kg of material, the range for aluminum is 11.2-12.6, and the range for magnesium from 18-45.

As another factor, the production of EV battery packs—especially in long range EVs—adds to the production-side carbon burden of those vehicles.

According to Greg Archer, Director, Clean Vehicles at T&E, T&E is in favor of eventually shifting to a full lifecycle as the basis for future car CO2 regulations—but not until after 2030.

We believe that given the relatively low level of EV penetration before 2030 (probably around one-third to one-half of new sales) and the need to incentive this shift, a tailpipe metric remains appropriate for the post 2020 regulation for 2025 and 2030 targets. Until then fuels and vehicles should be regulated separately. This is because the auto industry could not be fully responsible for their targets otherwise.

Beyond 2030, the tailpipe emissions become an increasingly small share of the total emissions and production emissions more so (especially the processing of raw materials) so a life-cycle metric should be used. To facilitate this, the post-2020 regulation should include a requirement to develop a life cycle assessment (LCA) approach and a mandatory reporting requirement for manufacturers. In this way data could be assembled and methodologies refined such that by 2025 (when a post 2030 regulation will begin to be discussed) there is a baseline of evidence and experience on which to base a new LCA regulation. We would not design regulations to combine different environmental issues and keep CO2 and air pollution regulations separate.

T&E is not in favor of WTW (well-to-wheel approaches) because the target is shared between carmakers and fuels suppliers. If one party fails to deliver the other will not be willing to do more—the target will simply be missed regulating the sectors separately is the only practical form of implementation.

—Greg Archer

September 18, 2017 in Diesel, Emissions, Engines, Lifecycle analysis | Permalink | Comments (18)


This study is rubbish as diesel engines outlast gasoline engines twice as long for a multitude of reasons. Diesel is a lubricant as opposed to gasoline being a solvent, cooler combustion temperature, and simply built stronger as they are still use iron blocks.

In comparison to a pure battery electric vehicle you'd have to replace the batteries about halfway of a diesels lifespan needing rebuilding. In a range extender EV such as Chevrolet Volt the battery will last longer with out having to go out of your way to stay to strict depth of charge habits.

The far right bar is labeled "BG". I looked at the report and could not find the definition of "BG". Anyone?

@Clif Jacobs

Based upon this quoted text I'd speculate bio-gasoline

"Similarly, a 5% bio-blend is assumed in gasoline for consistency, using the EU average shares taken from ePure: corn (38%), wheat (37%), sugars (14%), etc."

So, if our cars have lower fuel efficiency we drive less and consume less fuel, or?... Of course this study is as biased as a study ever can be.

I agree this is a highly biased study.

Even diesel-hating CARB has lower upstream GHG emissions for ULSD than gasoline (per MJ) in its "Low Carbon Fuel Standard" regulation, and biodiesel/renewable diesel from crop oils has lower upstream GHG emissions than ULSD, even with the controversial indirect land use change included.

@SatoruRyu: The rest of the car isn't built any better than the gasoline equivalent, modern diesels have expensive emissions control systems that can easily put the vehicle beyond economic repair when they fail (to avoid local pollution problems). Plenty of reasons why a diesel doesn't have significantly longer life than a gasoline vehicle in the real world.

And, regarding your other points, diesel being a not terrible lubricant only affects the fuel system (which is also working much harder to atomize the fuel, due to the much lower volatility and resulting much higher pressures required), and many diesels use aluminum blocks nowadays.

No this study is not rubbish. Sadly, Euro-diesel has turned out to be an expensive fraud in bigger ways than the study shows.

Particulates, famously associated with diesel, are a bigger cause of heat island and global warming in all prabability than CO2 alone. Your GCC records glacial melts as far away as Tibet from dropped particulates (what do you think makes sunsets so red?). NOx is a powerful greenhouse gas, and you may add to this the decline in performance and service of diesels, which tolerate engine knock due to lack of maintenance, as well as drive train burnout of lubricating fluid that we see so often among those old tractor trailers on my turnpike.

What about the emissions costs of recommended warmups and cooldowns?

Note the energy and emissions costs per kilogram of manufactured aluminum v. steel, as well as magnesium. How does structural value comport to weight? Your best best for lifetime vehicle efficiency by mass is probably stainless steel, which varies in grade, workability, and serviceability, not aluminum. Certainly not mild steel, but unless we see a full fledged recycling program of Al and SST, we may not realize ultimate energy economies over mild steel, which becomes junk with paint melted into the iron. Noguidance here for vinyl resins, fiberglass or graphite.

European refineries are much smaller and less consolidated than in the US, adding to inefficiency, as does the tilt toward lower grade, higher sulfur feedstock (the refineries must get rid of the sulfur, if the gas stations don't). What would help is the use of cogen to heat refineries and provide shift steam, which would add about 8% to useable feedstock.

One more thing. I can assure you VW builds rust buckets, which are no help, if such cars really are the Euro-standard.

ULSD removed much of the the lubricating ability of diesel oil, so, a projected diesel engine life cycle is not as long as before ULSD was required.

Studies like this, based on obsolete technology are of little value in they are beating dying horses. Both gas and diesel internal combustion engines are destined to be replaced by electric motors and that is happening much faster than we realize as drive line engineers design for the future and move to the compelling benefits of electric motors, especially for transporters that require high values of torque at low speeds.

Diesel Buses, long haul and short range Trucks, are all in the cross hairs of engineering firms because recent studies, using on the road test vehicles, prove a 6 to 1 better operations cost factor when operating electric instead of diesel or natural gas. What bus/trucking firm wouldn't want those savings.

@kalendjay, just to be clear, N2O (nitrous oxide) is the powerful greenhouse gas to which you're referring and is not considered "NOx".

NOx = NO (nitric oxide) + NO2 (nitrogen dioxide). Neither NO or NO2 are considered greenhouse gases; atmospheric lifetimes are much too short.

@kalendjay You are naive and are being anti-science in your ideology while using junk science to support your claim.

"drive train burnout of lubricating fluid that we see so often among those old tractor trailers on my turnpike."

Those engines easily last 500K miles - 1 million miles before an absolute teardown. So until you show me an EV tractor trailer single battery pack that lasts that long you are pushing pipe dream economics claiming to be climate science. Even with short hauling distances utilizing "quick charge DC systems" typically degrades a battery which even Nissan discourages doing so.

As higher amp charging current = more heat = more resistance = faster degradation. When it comes to battery long term lifespan is depth of discharge per cycle hence why the Chevrolet Volt outlast full blown EV battery long term life span. Also, consider they cap charging to level 2 charging systems meaning a 3-4 hour empty to full charge.

I lost my 2.0 liter VW TDI far short of its first rebuild interval.  The odometer read 156,384 miles and the efficiency I measured was every bit as good as the day I bought it; it was a long way from needing a ring or valve job.  Most of that mileage was running on ULSD.  I'd still be driving it today if it wasn't wrecked.

That said, I'm achieving much better than 3x the fuel economy using PHEV.  Level 1 charging takes ~5 hours, and that's mostly what I use.  This is good enough.

It wouldn't be at all difficult to put level 1 charging almost everywhere.  That would be sufficient to slash gasoline consumption by 2/3, roughly 6 million bbl/d in the USA.  Such a shift would devastate the oil-dependent economies.

@Engineer-Poet Expanding of level 1 charging is moot as I can with 100% confidence say the wires and labor installation costs are exactly the same. While the hubs might be different pricing I'd call it artificially inflated considering you could use them interchangeably as long as you didn't exceed amperage rating for the device.

There's also peak demand to worry about, and the fact that installing a charger won't draw enough business to pay for itself for quite some time.  This is why I expect the initial trend to be a dual-purposing of existing lighting circuits, because the wiring is already there.  Level 1 gets the job done.

@Engineer-Poet While your theory sounds plausible it would still be limited by the circuit breaker panel amperage rating. Which the average traditional (HPS, MH, or Mercury) parking lot street light varies from 250 watts - 400 watts.

So let's say there are 10 lights for simplicity x avg of 325 watts = 3250 total wattage. Now level 1 charging being 16 amps x 120 v = 1920 watts essentially allows only 1 vehicle to be charged. With minimal cost utilizing the exact god damn wire swapping the circuit breaker from 120v to 220v would be labor + ~$100 breaker allowing two vehicles to be charged in this scenario.

While they are already tapping the light pole to install a charging port hub they install a step down transformer back down to 120V to the remaining lights branched from the 1st circuit. To further mitigate wiring costs the charging hub would have to limit amperage during night to negate total amperage draw on circuit which should easily be within margin by swapping the bulbs to LED's.

Granted I'll openly concede parking lots typically have more than 10 lights in their parking lot meaning theoretically 2 - 4 could be on one circuit. Yet, it will be far cry from your proposed oil consumption reduction. Which 2 - 8 on exact same breaker panel circuit is the most rational pathway to your dream.

**correction last paragraph**
Which 2 - 8 on exact same wiring is the most rational step to your far fetched dream of devastating the oil industry.

While your theory sounds plausible it would still be limited by the circuit breaker panel amperage rating. Which the average traditional (HPS, MH, or Mercury) parking lot street light varies from 250 watts - 400 watts.

Something along those lines, yes.  Now substitute LED lamps for the others.  I see a gooseneck barn light replacing whatever... 42 W.  A LED area light replacing a 500 W HID equivalent:  160 W.  A replacement for a 400 W MH light, using 155 W.  The replacements use OTOO 1/3 the power and could be scaled down even more if desired; most parking lots are functionally over-lit.

Now consider the circuit ratings.  Continuous ratings are roughly 80% of peak, which is what the breaker is specified for.  Your 3250 watts of old lamps is on a 240 VAC 20 A circuit (4800 W peak, 3840 W cont).  You slash the 3250 W of lighting load to 1080 W by LED conversion, which gives 2760 W of excess capacity when the lights are on (the full 3840 W when off).  That's almost 2 full level 1 circuits with the lights on, and more than 2 level 1 circuits when they're off.  And you didn't have to pull a single inch of wire to put them in.

Now look at circuits with 25 or 30 A ratings.  Do you begin to see the possibilities here, already installed and waiting to be exploited?

Making double use of street and parking lot light circuits can ONLY be done where the original installation were over engineered and/or (to some extend) where existing lights were switched to very high efficiency LEDs.

From a practical-regulation point of view, cables and breakers would have to be updated in most if not all cases. Hurricane proof installations are highly recommended in many States.

You don't have to upgrade anything to get started.  All you need to do is to limit the vehicle's current draw to what the circuit has to spare, and the J1772 protocol is set up to do exactly that.

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