Request ID: FOI-1660-2324 Date published: 18 September 2023
You asked
Can you please tell me how much Particulate Matter (PM) and Nitrogen Oxides (NOx) a TX4 Diesel Taxi which you do licence creates? And does this LPG engine have less than the requisite emissions limits that TfL have set?
We answered
Our Ref: FOI-1660-2324
Thank you for your request received on 21 August 2023 asking for information about taxi emissions.
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm we do hold the information you require. You asked:
Can you please tell me how much Particulate Matter (PM) and Nitrogen Oxides (NOx) a TX4 Diesel Taxi which you do licence creates? And does this LPG engine have less than the requisite emissions limits that TfL have set?
Any new diesel TX4 taxi since 2016 has been built to conform to the Euro 6 emissions standard, although these can no longer be newly licensed in London.
However, there can be a substantial difference between the laboratory type approval test and real-world vehicle operations. For this reason, TfL refers to the COPERT emissions factors when estimating emissions from various types of road vehicle. The COPERT emissions factors are designed to represent how vehicles perform over a range of speeds and road types.
Using COPERT, a Euro 6 diesel TX4 taxi is estimated to emit 1.1g/km NOx in urban driving, Compared with 1.36g/km for a Euro 5 vehicle. Using standard fitment diesel particulate filters, Euro 6 levels of particulate matter emissions can be expected from any Euro 6 or Euro 5 diesel TX4.
Using the same COPERT estimates, but taking account of the LEVC ZEC taxi being a petrol plug-in hybrid, the NOx emissions are estimated to be 0.03g/km NOx under the same driving conditions, while a TX4 taxi, converted to LPG, typically emits 0.36g/km NOx. Therefore, an LPG converted TX4 taxi emits ten times more NOx than the LEVC ZEC vehicle, but two thirds less than a Euro 6 diesel TX4 taxi. Please note there are specific conditions for eligibility to convert to LPG on a London licensed taxi.
Unlike NOx, CO2 emissions are directly related to the fuel consumption of the vehicle. The Euro 6 diesel TX4 taxi is estimated to emit 220 g/km CO2 under urban driving conditions based on COPERT emissions factors, while the LPG converted TX4 is estimated to emit about 240 g/km. The plug-in hybrid LEVC ZEC taxi is estimated to emit around 55 g/km under similar driving conditions, provided that the battery is charged as necessary.
If this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.
Please see the attached information sheet for details of your right to appeal.
Yours sincerely
Gemma Jacob Senior FOI Case Officer FOI Case Management Team General Counsel Transport for London
