Conversion of a commercial gasoline vehicle to run bi-fuel –(hydrogen-gasoline) – dec 27 2025

D.Sa ´ inz, P.M. Die ´guez, C. Sopena , J.C. Urroz, L.M. Gandı´a*

Escuela Te ´cnica Superior de Ingenieros Industriales y de Telecomunicacio ´n, Universidad Pu ´blica de Navarra, Campus de Arrosadı´a, E-31006 Pamplona, Spain

international journal of hydrogen energy 37 (2012) 1781 e1789

Abstract

Bi-fuel internal combustion engine vehicles allowing the operation with gasoline or diesel  and hydrogen have great potential for speeding up the introduction of hydrogen in the  transport sector. This would also contribute to alleviate the problem of urban air pollution.  In this work, the modifications carried out to convert a Volkswagen Polo 1.4 into a bi-fuel  (hydrogen-gasoline) car are described. Changes included the incorporation of a storage  system based on compressed hydrogen, a machined intake manifold with a low-pressure  accumulator where the hydrogen injectors were assembled, a new electronic control unit  managing operation on hydrogen and an electrical junction box to control the change from  a fuel to another. Change of fuel is very simple and does not require stopping the car. Road  tests with hydrogen fuel gave a maximum speed of 125 km/h and an estimated  consumption of 1 kg of hydrogen per 100 km at an average speed of 90 km/h. Vehicle  conversion to bi-fuel operation is technically feasible and cheap

 

1. Introduction

Almost all important world car manufacturers are developing  hydrogen fueled vehicles. Most of them are fuel cell electric  vehicles (FCEVs) [1] although some companies are also  developing cars and buses powered by hydrogen fueled  internal combustion engines (H2  ICEs); this is the case, for  example, of BMW, Ford and Mazda. This fact, along with  the parallel development of hybrid and full electric powered  vehicles, evidence the current interest and at the same  time concern for the transport sector. This is due to its almost  complete dependence on oil-derived fuels and its main associated enviromental problems: urban air pollution and  greenhouse gas emissions. Cost-effective production of  hydrogen and electricity, ideally from renewables, but also from nuclear energy and low-CO2 technologies (e.g. natural gas reforming and coal gasification with CO2  capture and  sequestration) and their introduction in the transport sector  are key milestones towards a sustainable energy economy  .  

 

Critics with the hydrogen fuelled internal combustion  engine vehicles (H2  ICEVs) often argue that these vehicles are  inefficient and that require large fuel tanks, concluding that  they do not offer any advantage. Against this argument it should be not forgotten that both fuel cells and ICEs are constrained by the same maximum efficiency that is established  by the second law of Thermodynamics [8]. On the other hand, some recent thermodynamic studies as the work by  Nieminen and Dincer, show after a comparative second law  analysis for naturally aspirated gasoline and hydrogen fueled  spark ignition ICEs, that the H2  ICE achieved an exergetic efficiency of 41.37% whereas for the gasoline engine it was 35.74%

 

For more information in this excellent study click on this link

https://hydrogenfuelsystems.com.au/wp-content/uploads/2025/12/Conversion_of_a_commercial_gasoline_vehi-2.pdf

 

Conclusions

It has been shown in this work that the conversion of a commercial gasoline vehicle into a bi-fuel (hydrogen-gaso-  line) car is technically feasible and relatively cheap (about  6000 V in equipment and 200 man-hours). Obviously these  costs would be much lower in the event of a series production.  The possibility of bi-fuel operation is considered very impor-  tant as it is possible to use hydrogen for undemanding urban  routes and reserve the use of gasoline for longer trips by road.  The change from a fuel to another is very simple and does not  require stopping the car. This type of vehicles have the  potential of reducing the problem of urban air pollution and  accelerating the introduction of hydrogen in the trans-  portation sector because the current infrastructure of the  powerful automotive industry could be exploited for their  mass production. Perhaps the main problem that would  remain is the storage of a sufficient amount of hydrogen to  assure a reasonable autonomy although bi-fuel operation  could significantly alleviate the requirements of the storage  system in the short term.

 

 As for the vehicle conversion the main modifications are as follows:

1. Adding a hydrogen storage system, in our case hydrogen gas cylinders at 200 bar placed in the car boot, and a new  fuel line connecting the storage system with a low-  pressure hydrogen accumulator where the hydrogen  injectors are assembled.
2. Machining the intake manifold to allow the entry of hydrogen
3. Incorporating a new programmable electronic control unit that manages hydrogen operation and an electrical  junction box that allows controlling the change from  gasoline to hydrogen and vice versa.  The performance of the bi-fuel vehicle has confirmed the  superiority of hydrogen over gasoline operation in terms of  thermal efficiency and fuel consumption. Nevertheless, the  bi-fuel vehicle described in this work is not fully optimized.  Aspects such as the modification of the drive ratio and  improved hydrogen storage systems are under consideration  for future works.

Saturday, December 27, 2025