Log in to the online community

Want to post a reply? You'll need to log in
We need your help to tackle the transport challenge!
Our aim is not to “drain the ocean” in a few months but to add a voice of engineering insight to the debate, demolish potential myths and legends and suggest some sensible ways forward. We don’t expect to achieve pinpoint accuracy in our investigation, but we can be honest about that. We want to establish some genuine truths and point to where more work or funding should be focussed. We need more information and guidance to existing reliable reports and research on carbon in materials mining and manufacture, infrastructure provision, renewal and maintenance, and end of life recycling. Please share your thoughts by commenting below.
9 Replies
Roger Bryant
297 Posts
These are some calculations I made and posted on here a couple of years ago. This is based on Germany but I don't think the UK's numbers are that different:
There is a lot written regarding the replacement of fossil fuelled (petrol and diesel) cars with electric cars. Some suggest it is easy, others suggest it is impossible. I decided to look briefly at the electricity requirements required to do this in Germany.
First step how much petrol and diesel is currently used?
From the IEA
Germany petrol and diesel consumption 2010-2011.
Petrol 450 000 barrels per day
Diesel 1050 000 barrels per day
As a cross check on the total consumption:
Total consumption petroleum consumption for Germany 2015
2 372 000 barrels per day
Next step what is the electrical energy equivalent of 1 barrel of Petrol/Diesel? From a couple of sources:
1 barrel (crude) is 1,700 kilowatt hours 
A barrel of oil contains about six gigajoules of energy. That’s six billion joules or 1667 kilowatt-hours
If we take 1.7 MWh per barrel for petrol annual automotive energy input is:
Petrol 765 000 MWh per day= 765 GWh per day = 279 000 GWh = 279 TWh
Assuming an efficiency of 20% for a petrol vehicle the energy required for petrol automotive use in Germany is 55.8 TWh per year.
Taking an overall efficiency for an electric vehicle to be 80% (electricity transmission losses, battery charging efficiency) replacing the petrol vehicles with electric vehicles would require 70 TWh per year.
What proportion of the diesel is for automotive use against road or rail transport is not obvious. Suggesting a total of 100TWh for the annual automotive consumption seems reasonable.
If all the diesel consumers were replaced by electric vehicles the annual electricity consumption would increase by around 220 TWh per year
 Currently Germany produces around 600 TWh of electricity annually.
 Increasing this to 700 TWH to allow for the charging of electric cars is not trivial, nor is the reinforcement of the distribution infrastructure. Increasing to 820 TWh to replace all fossil fuelled transport is probably impossible in the suggested time scales.
Best regards

Roger Bryant
297 Posts
This has also been previously posted on here looking at the overall problem. It is encouraging that the engineering comunity is actually starting to look at the reallity:
OK so we have a problem that requires engineering solutions. The engineering community should be part of the solution but I don’t see any concrete action. There is a lot of rhetoric and virtue signalling but no planning, no road maps of how to reach a solution, no estimates of resources and time scales.

Ms Thunberg can berate as many political leaders as she likes, but without engineering nothing will actually change. Resources will always be limited and these will control the time scales. Moving the ‘CO2 Neutral’ target from 2050 to 2100 may not be ‘kicking the can down the road’, it may be the optimum way. Is it sensible to shut down generating stations before the end of their useful life and so waste some of the energy and materials used in their construction, probably not.

Firstly what is the problem to be solved? The UK shall be ‘CO2 Neutral’ by 2050. What does that actually mean? What does CO2 Neutral mean?

1) Don’t burn anything that contains carbon?

2) Burn things containing carbon and then stick the carbon back in the ground somehow?

3) Burn things containing carbon and buy carbon credits (indulgences)?

The technology for 2) does not exist in  an industrial form yet and probably won’t by 2050. It might be available by 2100. If the whole world is trying to become CO2 neutral there won’t  be enough carbon credits to go round for 3) to be practical so that leaves 1).

1) means don’t burn coal, oil or gas (possibly wood as well) for:

a) Electricity generation
b) Process heating
c) Domestic heating
d) Transport

The technology generally exists to replace fossil fuelled transport with electric/hydrogen power. The electricity and hydrogen need to be produced somewhere which increases the load on a) Electricity generation. A large amount of infrastructure need to be built for charging EVs and distributing hydrogen for fuel cell or combustion engined vehicles. We need to increase our ability to produce battery or fuel cell powertrains, including the supply chain, by a factor of 100. Is this possible by 2030, 2040 or 2050 depending on which rhetoric you choose?

How do we replace oil and gas for domestic heating? The first step is obviously to reduce demand by reducing heat loss. This is quite difficult with a lot of the UK’s housing stock and previous attempts at improving insulation have resulted in numerous problems with damp etc. There will still be a need for heating so how can this be achieved?

i) Ground or air source heat pump.

ii) Electrically heated storage system.

Both of these increase the load on a) Electricity generation and may be difficult to install in existing UK properties. Changing cooking from gas to electric is relatively easy but further increase the load on the electricity generation and distribution systems.

I don’t have any answers for process heating. How can we manufacture concrete and smelt metals without burning gas or oil? Aluminium smelting and some of the refining processes can be done electrically but that also increases the load on a) Electricity generation.

 How to proceed with electricity generation and distribution? The load on the system has been increased by the other solutions and we have to shut down more than half of our existing capacity. What are the alternatives?

Nuclear is a good start for base load but the current generation of reactors have slow response times to changing loads. It’s unlikely that newer generation systems will be available in time to be on stream by 2050. They will be available by 2100. The fuel cycle will also need to be supported by breeding and reprocessing. Could we build ten or more nuclear power plants by 2050?

I don’t think Solar PV is viable at the UK’s latitudes, in southern Spain it may be.

Wind is an option, however the low energy density and moderate capacity factor will require many turbines spread over large areas. The intermittency will remain a problem and will require a complementary system of storage or back up. The concrete and steel requirements for wind power are greater than those for nuclear power which offers a significantly greater service life. Could we build and install enough wind turbines by 2050?

Tidal barrages/pumped storage. Tidal barrages also require vast areas due to the limited head (tidal range) and slow cycle time (11hrs). They also have an intermittency but it is plannable and can be managed by multiple basins with some loss of total efficiency. A useful contribution to the problem would require a barrage on all the UK’s major estuaries. The barrages could also be used as pumped storage facilities to support wind power but that removes the generating capacity. Separate pumped storage facilities could be built to support wind power but the likely, mountainous, regions are well away from the generation sources and end users. This will require expansion and reinforcement of the grid system. Are there enough places to install tidal and pumped storage systems? Could enough be built by 2050?

If the above can supply enough electricity what about the distribution system. In another thread it was noted that domestic distribution is based on an average 6 or 7 amps single phase per property. In a CO2 Neutral world that is not enough. Additions are required for EV charging, cooking and heating. Will doubling the value be enough? How can that sensibly be achieved? I would suggest reinforcing at higher voltages and doubling the number of substations to reduce the disruption of the 415/240V system to a minimum. How many new substations would that be to be built and installed, 1000s?

This is a possible road map to a CO2 Neutral future. It is full of assumptions that can be challenged. It contains many open questions. It does not contain estimates of the amount of raw materials involved. Is it possible by 2050? I don’t think so. Is it possible by 2100? Maybe. Is it necessary?
Best Regards

Thank you for this!  The absolute number you calculate for Germany may not be exactly the same as for UK but the big picture is the same.  Very useful.  Did you go on  to guesstimate what the carbon content of the new generating capacity would have to be to fulfil this extra energy need or be able to point to any work you are aware of around that, please?
Hum, now you can see why we are determined not to boil the ocean.  It will be enough to demonstrate the reality for Transport.  We've got some good stuff on the carbon footprint of a new battery EV or PHEV car.  Hydrogen seems to be a difficult topic with much lobbying for "blue" hydrogen (basically made by burning fossil fuel) and the calorific content of the product.  We can already say that with current technology a diesel train that had a fuel range of say 1200km would, if the engine and fuel tanks etc were replaced by battery power, might do 350km and if by hydrogen might do 100km.  However, where we need more help now is in the construction and maintenance carbon of roads, railways and ports / transfer depots, as well as in the embedded carbon in new trains, planes and ships.
Roger Bryant
297 Posts
The carbon and resources requirements for additional generating power is difficult to determine. Information like the amount of concrete and steel required and the amount of earth to be moved is easy to find for new Nuclear Power Plants. It is very difficult to find similar information for onshore wind and even harder for offshore wind. With the limited information I could find 3GW of wind, assuming ~30% utilisation required as much concrete as Hinkley Point C. The wind power has an expected life of 20-25 years, Hinkley Point C 60 years plus. Most wind and solar costings are parasitical. The backup and storage problems are left to someone else to deal with/pay for. There is a frequently bandied around figure that wind power pays back the energy used in it’s construction in around a year. I have not found figures to back that up or to confirm what is included. I have to assume that this is measured at the terminals of the wind farm and does not include the transmission and backup/storage installations. The energy payback  time for solar PV seems even more dubious, ranging from a few years in southern Spain to probably never in northern latitudes. I currently cannot accept biomass burning as having any green credentials at all.
As you say hydrogen is a problem due to the large conversion losses. Blue hydrogen is a waste of resources. You are burning fossil fuel to create the hydrogen and then burning more fossil fuel to capture and store the carbon that is released. Producing hydrogen by electrolysis is inefficient. The numbers I have seen suggest 3 MWh of electricity is required to generate 1 MWh equivalent of hydrogen. There are some interesting comments in this article.


I don’t know if there is a direct, thermal, means of producing hydrogen with nuclear power but to produce it by electrolysis just seems wasteful.
Unfortunately most of these ‘green’ ideas assume infinite resources and that these resources can be obtained carbon free. Currently anything you build requires the burning of fossil fuels. To make cement, to make steel, to make copper wires, to refine rare earths all generate emissions. If we try to change too quickly we will actually increase rather than reduce emissions in the short to medium term.

Is it better to run our current systems to the end of their useful lives rather than prematurely scrapping them and wasting the resources invested in them?

Are the 2030 or 2050 targets realistic or even sensible?

Roger Bryant
297 Posts
“Our aim is not to “drain the ocean” in a few months but to add a voice of engineering insight to the debate, demolish potential myths and legends and suggest some sensible ways forward.”

Let’s have a look at some of the myths and legends, do we have climate problem or a climate emergency. A recently released paper looks at 79 predictions of climate-caused apocalypse going back to the first Earth Day in 1970. It notes that 48 (61%) of the predictions have already expired as of the end of 2020.


Maybe some people want there to be a climate emergency for idealistic or control purposes.  I looked at this in this post on here:


As I said in that piece I fully support the reduction in the use of our finite resources, reduction of pollution and reduction of our impact on the planet. I don’t think that targeting CO2 is the correct way to achieve these goals.

Where does the CO2 driven climate emergency come from? Mathematical models and extrapolations.  If you look at the actual data you can maybe find a problem but certainly not an emergency.  The climate has changed, is changing, and will continue to change with or without us. What do we actually know?
The longest directly measured temperature series is the Central England series held by the UK Met office:


If you look at the chart, the temperature rose by more than 1.5°C between about 1700 and 1730. The temperature rose around 1°C between about 1975 and 2000. Were both of these man made? Were both of them natural? How do the climate models explain the rise in the 1700s. The temperature is then fairly flat from around 2000.
The longest measured CO2 series is from Mauna Loa:


This is always shown with an offset zero. It is a fairly trivial task to import the raw data and draw a ‘normal’ graph starting at zero.

What about global temperatures? There are several series available. As the IET is UK based I will use the ones from the Met office:


The various temperature series are in reasonable agreement but they only go back to 1900. If you look at the Central England series quite a lot happened before then. There is also a significant difference between the north and south hemispheres. For the northern hemisphere there is somewhat dubious attempt to show an increasing rate of temperature rise by starting from a cool spell in the 1970s.

The next graphs come from the IPCC AR5 Working Group 1, The Physical Science Basis:


On page 18 it shows the model outputs in red with a confidence band. Measured temperatures are black. The measure temperatures are always below the model and are starting to leave the confidence band. It also records the reduction in the rate of warming after 1998, the so called ‘Pause’. I am waiting to see how AR6 explains the continuing discrepancy between the models and reality.

The IPCC uses four scenarios, RCP2.6, RCP4.5, RCP6.0 and RCP8.5. RCP8.5 is the worst case and it has been suggested it could be difficult to dig coal fast enough to achieve it. Most of the ‘Emergency’ is based on this scenario. RCP6.0 is around business as usual, RCP4.5 is if an effort is made to reduce CO2 emissions and RCP2.6 is an unlikely best case.
This is shown graphically in this article:


Figure 4 shows it quite well.

So do we have a problem or an emergency? Is it more sensible to make changes over a longer timescale, replacing life expired items rather than scraping functional items

What is important is reduction in the use of finite resources, reduction in pollution, reduction in change of land use and sustainable use of natural resources such as fish. Are the current plans in accordance with this?

-Blue hydrogen is not. It is increasing our consumption of finite resources.

-Green hydrogen is dubious due to the large conversion losses. Using wind generated electricity will increase the energy payback time significantly possibly to zero when the energy requirements of the electrolysis plant are taken into account. Using solar PV is unlikely to have an energy payback.

-Biomass is in general not, burning actual wood waste is probably ok but the amounts are quite limited.

-Wind and solar PV are again dubious as they currently only exist parasitically. The true energy payback and resource consumption will only be available when they deal with their own intermittency and backup/storage.
Again very helpful and I’ll keep in my mind your rule of thumb re 3:1 Electricity/Hydrogen.  I have now got some good material from RSSB on trains and have approached HS2 and NR for infrastructure values.  Certainly today steel and concrete manufacture is fossil-fuel powered.
This report from last April looks into the lifecycle emissions of EVs: https://www.transportenvironment.org/sites/te/files/downloads/T%26E%E2%80%99s%20EV%20life%20cycle%20analysis%20LCA.pdf

Our own analysis suggests that electricity generation in the UK would need to be around 600-800TWh by 2050 (depending on what else is assumed) in order to support the net zero transition, in particular, by way of electrification of heat and transport (https://es.catapult.org.uk/reports/innovating-to-net-zero/). This electricity would need to come from low carbon sources such as offshore wind, nuclear and other renewables but these might be supported during peak demand periods by gas plants and an array of storage options (battery, thermo-mechanical and hydrogen storage). Overall, the electricity being supplied to EVs would/and is likely to be getting lower in carbon intensity. 

13 Posts
Dear Professor Andrew McNaughton,

Thank you for opening up the discussion about this issue to this community and welcome to the forum! I hope that you will find the input of the community on the whole helpful, informative and supportive.

I would like to take a few minutes to address two specific parts of your original introductory piece found at this URL: https://www.theiet.org/impact-society/sectors/transport/transport-blog-posts/towards-a-net-zero-carbon-future-the-true-scale-of-the-transport-challenge/

Just before that, I would like to join Adam Thirkill in pointing out that Transport & Environment are well ahead with this kind of analysis and would encourage you to look at what they, and their network of partners across Europe, have been working on for many years to help you achieve your goals with your own project.


This piece did not make it clear why you are undertaking this work. Why are you undertaking this work?

It suggests what you wish to try to do, what you hope the deliverables will be and how you intend to try to get there, but not why you are doing it.

My belief is that being as clear and transparent about your motivations (what do you believe) as possible is vital to inspire a community into constructive (altruistic) action, and that this is missing from your writing at the moment.

If I have misunderstood your writing, then I apologise that I did not understand what you were saying and humbly request a clarification.


Secondly, I regret to inform you that I believe you appear to have been misled, even as you get started on this topic. I was alarmed enough when I saw it, that I felt I must take some time to try to help or to understand whether I have been misled instead.

I would be glad to come to an understanding about this matter with you. I am sure you expect nothing less from IET members that to hold yourselves and each other to the highest professional standards and you will not take it personally that I am attempting to do the same.

"Research in Europe suggests that the carbon embedded in mining raw materials, manufacturing and transporting a new battery for say an electric SUV is so large that it would have to run upwards of 120,000 miles on 100% green electricity before its lifetime carbon footprint was less than a new petrol version of the same vehicle!"

As a scientist, I feel compelled to request you make clear your sources for this claim. I am willing to believe you have high quality, transparent sources for this claim, which is why I feel it is acceptable to politely ask to see them.

My fear is that you have seen subsequent reporting of a debunked, PR activity with poor transparency as to their "why" for commissioning the extensive work put into this information campaign. As an alternative point of view to your sources, I implore you to take a few minutes to read the words of Michael Liebreich of Bloomberg New Energy Finance and see both sides of the coin. I believe I can trust in his appraisal of the detailed technical analysis because he holds a first class degree in Engineering from the University of Cambridge and has spent much of his career looking into these issues.

My sources are the following:



I am trying to help because I believe that sensible use of resources now if crucial to achieving decarbonisation goals, and the more scientific consensus can be built the greater our chances of minimising the destabilisation of Earth's life support systems.

Life creates conditions conducive to life. Shall we all try and help engineering and technology do the same?

Thank you very much for your time and the work of you and your colleagues.

Keep safe and have a nice day!


P.S. In this spirit of honesty, I wish to make it clear that I am British engineer, trained in the UK. I work as professional research and development engineer for a world-leading developer of hydrogen fuel cells, based outside the UK. Despite this, my view is that renewable hydrogen technology is not a prudent technology for the UK to choose to decarbonise transport outside of shipping and aviation. This may appear counter-intuitive but I will try to be honest and impartial about the strengths and weaknesses of the technology I develop, as well as I can.

P.S.S. I wish to add that I believe it is very important to assess the risks of potential 'bait-and-switch' strategies when evaluating proposals for transportation systems based on hydrogen, or more generally "e-fuels" or "biofuels", because the potential for these strategies jeopardise our chances of achieving our (legislated) decarbonisation requirements. If you would like more information or to have a discussion about this, you need only ask.


Log in

Want to post a reply? You'll need to log in