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Stock-flow modeling suggests energy transition within transportation will take several decades

Using a stock-flow model based on data from Norway, a researcher at the country’s Institute of Transport Economics (TØI) has calculated the energy transition time lag for motor vehicles under a number of scenarios.

In his paper in the journal Energy Policy, Lasse Fridstrøm finds that in the most optimistic scenario for the energy transition affecting Norwegian registered vehicles, zero emission vehicles (ZEVs) would constitute 90% of the flow of new passenger cars in 2024; however, 90% penetration of ZEVs into the stock of passenger cars would not occur until 2039.

For light duty freight vehicles (LDVs), the corresponding milestones would be reached in 2026 and 2040, respectively, according to the same optimistic policy scenario.

The stock-flow modeling approach accounts for the stock of vehicles and the flows into and out of this stock.Based on the Markov chain principle—by which the flows and stock in year t depend only on the stock of the previous year t-1, Fridstrøm’s model projects year-by-year changes in the fleet of vehicles in each category, classified by age, weight and powertrain (energy) technology.

The model specifies 11 technologies: gasoline internal combustion engine (ICE); diesel ICE; battery electric vehicle (BEV); plug-in hybrid electric vehicle (PHEV) with gasoline ICE; PHEV with diesel ICE; non-plug-in hybrid vehicle (HEV) with gasoline ICE; HEV with diesel ICE; hydrogen fuel cell electric vehicle (FCEV); natural gas ICE; kerosene ICE; and other.

The four different scenarios differ in terms of new vehicle acquisitions, but are identical in terms of transition rates—set in accordance with the average observed annual rates during 2010–2015.

  • The trend scenario is essentially an extrapolation of the changes in market shares observed between 2010 and 2015.

  • The ultra-low emission (ULE) scenario is designed to meet the Norwegian governments ambitious targets for the uptake of zero- and low-emission vehicles—by 2025, all new passenger cars and all new urban buses are to be BEVs or FCEVs. The same applies to new LDVs (cargo vans), to three quarters of all new interurban buses and coaches, and to half of all new HDVs (trucks and semitrailer tractors) by 2030.

  • The low emission (LE) scenario sees zero-emission automobiles obtaining market dominance at least by 2030.

  • The business-as-usual scenario posits new automobile sales changing only slowly from the market shares observed in 2016.

Share of zero emission passenger cars, in four scenarios. Fridstrøm (2017). Click to enlarge.

To measure the speed of transition, Fridstrøm used three indicators: (i) the share of zero emission vehicles (ZEVs); (ii) the average energy consumption per vehicle or freight ton kilometer; and (iii) the average CO2 emissions per vehicle or freight ton kilometer.

Among his other findings:

  • For automobile energy efficiency, the lag between innovation and penetration typically varies between 8 and 15 years; the LDV lag varies from 7-8 years to more than 20 years. For HDVs, in terms of energy consumption fer freight ton kilometer, the energy efficiency lag varies from 12 to more than 25 years.

  • A 90% reduction in the car stock’s mean CO2 emission rate is projected to occur in 2037 according to the most optimistic (ULE) scenario, but no sooner than in the second half of the century—if at all—if the current trend continues.

… a relatively high speed of transition will occur only if governments make exceptionally forceful policy instruments to bear on new vehicle acquisitions. More realistically, the energy transition within road transportation will take several decades. Achieving such a transition will thus require long-time political perseverance and resolution.

—Fridstrøm (2017)


  • Lasse Fridstrøm (2017) “From innovation to penetration: Calculating the energy transition time lag for motor vehicles,” Energy Policy, Volume 108, Pages 487-502 doi: 10.1016/j.enpol.2017.06.026



And this is Norway, the leader by a mile in changing, with massive subsidies and exemptions courtesy of their oil revenues covering the cost.

A lot of enthusiasts notion of the speed of the change are off by a country mile, and there is plenty of time for alternatives like fuel cells or through the road on the move charging to move to the fore past the current front runners.


This chart shows growth of EVs as being almost linear, despite the present growth being exponential and increasing. It also has no mention of the fact that one little global event can dramatically increase the price of oil overnight, and that gasoline stations already run at very low margins and will forl as plugins increase, making it increasingly difficult to own an ICE vehicle.


A lot of detractors notion of the speed of the change could be off by a country mile in the other direction.


Norway is an exception...i.e. a country with plenty of oil and gas... and the highest usage of electrified vehicles.

USA and Canada, and many other countries with a good supply of low cost oil and gas, will or may not switch over as fast or much before 2050-2060?

Much better, lower cost batteries (800 to 1,000 Wh/Kg at well under $100/kWh) and improved FCs + electrolyzers; and H2 at under $3/Kg may provoke an acceleration, by 2030 or so.

More climate changes are required to convince the majority to do away with fossil fuel burning.


This all sounds true.
Lets hope that with sufficient effort we can see the most optimistic scenario improved on. Every last / % is the goal here.

For the present trajectory under 'ideal' scenarios remember that 90% of vehicles sold in say 2020 will be ICE and those will be around 15 years later on average.

The financial incentive to keep fossil fuels in the system is mind boggling. But the costs to do the same are beyond finite.

If it costs the vested interests more to stay in the business of carbon pollution owing to disruption or taxation, they are more likely to abandon the follie earlier.

We see how many coal power generators are ceasing to build new plant and the industry is seen as risky which in turn drives up costs.
The informed investors being risk adverse withdraw leaving yesterdays technology believers to count their stranded asset losses.
Successful and ethical financial institutions are sensitive to the bottom line and are forward thinking.
Those that aren't will continue to support risky investments for higher returns but they risk being stuck with junk portfolio.
When it comes to fast money for no or little effort ethics is often a minor consideration (if at all).

In the end it is clear that govt and legislators need to be supported to implement the necessary framework for speedy and effective transition to sustainable model.
At the same time those that don't or wont hear reason need to hear the deafening voice of objection and be removed from positions of influence.


Things can switch pretty quickly if there is a good enough push. In Ireland and the UK, we switched to diesel (70% new cars) because it was cheaper, give better MPG and Co2 and higher resale values. Obviously, we got it wrong wrt "local" pollution, but it shows what a push can do.
Switching to electric is not as simple as switching to diesel due to the range and time of charging, but it could happen.

There is nothing inherently good about EVs, they just have lower CO2 and pollution, and if you could achieve that in some other way, it would be just as good.
PHEV or some hybrid mix might be nearly as good.

The problem is to get people to switch when oil is so cheap.
if you look at Europe, where there is a lot of tax, very few people use hybrids. Hopefully the demise of diesel will cure this.

Also, even if Norway eschews HC fuels, they will just sell their oil at a slightly lower price to someone else who will burn it.


I'm with Paroway.  We're already on the verge of universal start-stop micro-hybridization and the elimination of engine-driven hydraulic pumps and A/C compressors.  Electric launch assist is an almost inevitable next step from there.

What's needed to go from that to a minimal PHEV?  Just a bigger battery and a charger, right?  It's a small step that could happen very quickly.  It would only take 3.4 Gigafactories to put 10 kWh into every LDV sold in the USA; just 1.7 to make it 5 kWh.  That ought to be enough to knock off 50% of liquid fuel consumption.

(My car's trip computer reported 49.1 average MPG over a leg that was about half 55 MPH, half 65 MPH; per the same, I'm averaging over 129 MPG.  The conventional hybrid is only rated at 39 MPG highway.  I'm pretty happy with it right now.)

Thomas Pedersen

I agree with E-P. I think the 48V systems are going to be a Trojan Horse and enable gradually increasing electrification as it makes sense. And along the way, the ICE will get completely new tuning and modes of operation, such as burn-and-coast. When integrated with topographic maps and intelligence (oh, it's 5:30, and we're going the same direction as usual Mon-Fri, so program the ECU to minimize gasoline consumption for that particular route, taking into account on-line traffic information).

I can't wait for cars to skip 1st gear entirely, because I loathe the sound they make in that gear. They rev too fast with no load, which makes for a very straining sound. Not like an engine under full power in 3rd or 4th gear, which is a quite pleasing sound - if you're into that sort of thing.

There are loads of expensive equipment to potentially shed, when there's an e-motor to take care of all the challenging load modes. Variable valve timing, cylinder cut-off, variable turbine geometry, turbo chargers, etc.

The Toyota hybrid system is complicated because their battery is too small. Ideally, there would be an e-motor with sufficient power and battery capacity to handle all driving in all but the highest gear. The ICE would only kick in from 40-50 mph or more. An ICE tuned for optimum efficiency at a narrow operating window (65-75 mph).

The current PHEVs are mostly overly complicated, using highly advanced (expensive) stock engines. Once customers and car makers start to 'trust' the electrical components, they should be more inclined to simplify the ICEs again.

And with that, gasoline cars could easily slash their effective gas consumption by a very large percentage - enough to make it less important whether BEVs take over entirely.


Balancing the carrot with the stick rather than believing the carrot can do all seems more realistic.

Technology needs to deliver but when faced with the well understood concept of dumping often inferior product to price sensitive consumers all parties need to be forward thinking.
The hidden costs are not small.
We saw how the market price of solar panels has halved twice and is close to halving again largely owing to investment spurred by favourable international legislation and a ready market.
The moneys invested by taxpayers and business has been recouped several times so far to every ones benefit (though some vested interests are not happy).

Regardless - technology will move on as it always must and I will be very surprised if the coming years and decades fail to deliver some game changing outcomes towards zero emissions.

20 years ago I would have said that solving the transport conundrum will be just a small step in the necessary direction. Today the situation remains but the industry and popular consensus is well advanced.


We are trying to find the right time and the best way to exchange our three (3) excellent 45 mpg Toyota HEVs with improved 55+ mpg HEVs or 100+ mpge FCEVs and or a the best mix of both.

The availability and non-availability of charging units and H2 stations will have to be fully considered.

The new (2018) Toyota Camry 55+ mpg Hybrid (and other similar HEVs) will be on the short list.


We are not going to go from less than 1% to over 90% EVs over night. This should be obvious to anyone who is realistic.


When we discuss the Norway case and the implication for electric car penetration, we always leave out one very important word. I’ll illustrate.

Here’s the usual story:
(1) Norway aggressively supports plug-in vehicles. The buyer pays considerably lower purchase tax (amounting to nearly the price of the vehicle in some cases), permits special lane privileges, forgives/eliminates city entry and road tolls, provides free parking, and heavily subsidizes charging at residences and workplaces. Norway has the highest price for petrol and diesel, greatly encouraging the use of stored electrochemical energy for personal transport. This is bolstered by enormous renewable energy supplies (hydroelectric). As a collateral influence, Norway’s excellent public transport system eases the pressure a driver may perceive about range, allowing a simple and affordable alternative if range is perceived to be limiting for some drives. Finally, Norway is both wealthy (with a sovereign “rainy day” trust of over US$1M per citizen) and characterized by a very “green” cultural consciousness.
(2) Norway’s market share of new LDV’s by Plug-Ins is 25%.

Have you figured it out? Hint: the word is missing from (2).

OK, here you go: the missing word is ONLY: Norway’s market share of new LDV’s by Plug-Ins is ONLY 25%.

If the story for Plug-Ins is so compelling AND it has the most verdant opportunity possible, why isn’t it 50% or more? And how will the rest of the world even come close? (Note: before you have a cow, please know I’ve been a Plug-In driver since 2013.)



Toyotas HEVs may be complicated but our three units have been in use for almost 4 years without a single problem.

They are highly recommended.


Herman, do Norway's subsidies include PHEVs?  Given my experience, I find it hard to believe that market share in the relevant segments would not push 100%.  If you could buy an EcoBoost Fusion and pay 100% tax on it, versus a Fusion Energi and pay 0% tax on it, you'd expect almost 100% of Fusions sold to be Energi models.

The limited offerings of PHEVs in other segments (like minivans and luxury cars) might explain why penetration is only 25%.  An untaxed Tesla is still going to cost several times as much as a 100%-taxed Yaris.


Subsidies for electrified vehicles are excellent to increase sales but should be based on total vehicle price and be limited to vehicles under $50K.

TESLAs and others over $50K should not qualify but electrified vehicles under $50K should get more, starting at $100/per increasing progressively with lower vehicle price. A ceiling of 50% of vehicle price could be used for new HEVs, PHEVs, BEVs and FCEVs.

A new progressive Federal carbon/gasoline/diesel fuel tax would be required to cover extra cost to make the project budget neutral?


The experience is already started in japan since last fall where the gasoline serial hybrid nissan note e-power have gotten instant sales leadership beating the prius on cost and mpg and driving pleasure. It can be improved with a plug-in version with solar roof.

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