2. The data we may collect about you

Personal data, or personal information, means any information about an individual from which that person can be identified. It does not include data where the identity has been removed (anonymous data). 

We may collect, use, store and transfer different kinds of personal data about you which we have grouped together as follows: 

• Identity Data includes first name, maiden name, last name, username or similar identifier, marital status, title, date of birth and gender. 
• Contact Data includes billing address, delivery address, email address and telephone numbers. 
• Financial Data includes bank account and payment card details. 
• Transaction Data includes details about payments to and from you and other details of products and services related to relevant transactions. 
• Technical Data includes internet protocol (IP) address, your login data, browser type and version, time zone setting and location, browser plug-in types and versions, operating system and platform, and other technology on the devices you use to access this website.  
• Profile Data includes your username and password, your interests, preferences, feedback and survey responses.   
• Usage Data includes information about how you use our website, products and services. 
• Marketing and Communications Data includes your preferences in receiving marketing from us and our third parties and your communication preferences. 

We may also collect, use and share Aggregated Data such as statistical or demographic data for any purpose.  Aggregated Data could be derived from your personal data but is not considered personal data in law as this data will not directly or indirectly reveal your identity. For example, we may aggregate your Usage Data to calculate the percentage of users accessing a specific website feature. However, if we combine or connect Aggregated Data with your personal data so that it can directly or indirectly identify you, we treat the combined data as personal data which will be used in accordance with this privacy policy. 

We may also collect some Special Categories of Personal Data about you including details about your race or ethnicity, religious or philosophical beliefs, sexual orientation, political opinions, trade union membership, information about your health, and genetic and biometric data. We do not collect any information about criminal convictions and offences. 

If you fail to provide personal data 

Where we need to collect personal data by law, or under the terms of the agreement we have with you, and you fail to provide that data when requested, we may not be able to perform the agreement we have or are trying to enter into with you (for example, to provide you with goods or services or to licence works). In this case, we may have to cancel the agreement you have with us but we will notify you if this is the case at the time.  

4. How we use your personal data

We will only use your personal data when the law allows us to. Most commonly, we will use your personal data in the following circumstances: 

• Where we need to perform the agreement we are about to enter into or have entered into with you.
• Where we need to carry out a task in the public interest or in the exercise of official authority vested in us.
• Where it is necessary for our legitimate interests (or those of a third party) and your interests and fundamental rights do not override those interests.
• Where we need to comply with a legal obligation.

To find out more information about the lawful bases upon which we will rely on to process your personal data, please refer to the Glossary below. 

Purposes for which we will use your personal data 

We have set out below, in a table format, a description of all the ways we plan to use your personal data, and which of the legal bases we rely on to do so. We have also identified what our legitimate interests are where appropriate. 

Note that we may process your personal data for more than one lawful ground depending on the specific purpose for which we are using your data. Please contact us if you need details about the specific legal ground we are relying on to process your personal data where more than one ground has been set out in the table below.  

Marketing 
We may use your Identity, Contact, Technical, Usage and Profile Data to form a view on what we think you may want or need, or what may be of interest to you. This is how we decide which products, services and offers may be relevant for you (we call this marketing).  

You will receive marketing communications from us if you have requested information from us or entered into agreements with us and you have not opted out of receiving that marketing. 

Third-party marketing 

We will get your express opt-in consent before we share your personal data with any third party for marketing purposes.  

Opting out 

You can ask us or third parties to stop sending you marketing messages at any time by contacting us or them at any time.  

Cookies 

You can set your browser to refuse all or some browser cookies, or to alert you when websites set or access cookies. If you disable or refuse cookies, please note that some parts of this website may become inaccessible or not function properly. For more information about the cookies we use, please click on the following link  http://www.pla.co.uk/Privacy-and-Cookies-Policy   

Change of purpose 

We will only use your personal data for the purposes for which we collected it, unless we reasonably consider that we need to use it for another reason and that reason is compatible with the original purpose. If you wish to get an explanation as to how the processing for the new purpose is compatible with the original purpose, please contact us [email protected].   

If we need to use your personal data for an unrelated purpose, we will notify you and we will explain the legal basis which allows us to do so. 
Please note that we may process your personal data without your knowledge or consent, in compliance with the above rules, where this is required or permitted by law. 

6. International transfers

We share your personal data within the PLA. This may involve transferring your data outside the European Economic Area.   Whenever we transfer your personal data out of the EEA, we ensure a similar degree of protection is afforded to it by ensuring at least one of the following safeguards is implemented:  

We will only transfer your personal data to countries that have been deemed to provide an adequate level of protection for personal data by the European Commission. 

8. Data retention

How long will you use my personal data for? 

We will only retain your personal data for as long as reasonably necessary to fulfil the purposes we collected it for, including for the purposes of satisfying any legal, regulatory, tax, accounting or reporting requirements. We may retain your personal data for a longer period in the event of a complaint or if we reasonably believe there is a prospect of litigation in respect to our relationship with you, or directly or indirectly concerning you. 

To determine the appropriate retention period for personal data, we consider the amount, nature and sensitivity of the personal data, the potential risk of harm from unauthorised use or disclosure of your personal data, the purposes for which we process your personal data and whether we can achieve those purposes through other means, and the applicable legal, regulatory, tax, accounting or other requirements. 

In some circumstances you can ask us to delete your data: see your legal rights below for further information. 

In some circumstances we will anonymise your personal data (so that it can no longer be associated with you) for research or statistical purposes, in which case we may use this information indefinitely without further notice to you.  

10. Glossary

LAWFUL BASIS 

Legitimate Interest means the interest of our business in conducting and managing our business to enable us to give you the best service/product and the best and most secure experience. We make sure we consider and balance any potential impact on you (both positive and negative) and your rights before we process your personal data for our legitimate interests. We do not use your personal data for activities where our interests are overridden by the impact on you (unless we have your consent or are otherwise required or permitted to by law). You can obtain further information about how we assess our legitimate interests against any potential impact on you in respect of specific activities by contacting us. 

Performance of Agreement means processing your data where it is necessary for the performance of a agreement to which you are a party or to take steps at your request before entering into such an agreement. 

Comply with a legal obligation means processing your personal data where it is necessary for compliance with a legal obligation that we are subject to.  For example, in order to comply with the NHS Test and Trace procedure introduced as a result of COVID-19. 

THIRD PARTIES 

External Third Parties 

• Service providers acting as processors internationally who provide IT including data storage and system administration services.
• Professional advisers acting as processors including lawyers, bankers, auditors, brokers and insurers based in the UK who provide consultancy, banking, legal, insurance and accounting services.
• HM Revenue & Customs, regulators and other authorities acting as processors or joint controllers based in the United Kingdom who require reporting of processing activities in certain circumstances.

YOUR LEGAL RIGHTS 

You have the right to: 

Request access to your personal data (commonly known as a "data subject access request"). This enables you to receive a copy of the personal data we hold about you and to check that we are lawfully processing it. 

Request correction of the personal data that we hold about you. This enables you to have any incomplete or inaccurate data we hold about you corrected, though we may need to verify the accuracy of the new data you provide to us. 

Request erasure of your personal data. This enables you to ask us to delete or remove personal data where there is no good reason for us continuing to process it. You also have the right to ask us to delete or remove your personal data where you have successfully exercised your right to object to processing (see below), where we may have processed your information unlawfully or where we are required to erase your personal data to comply with local law. Note, however, that we may not always be able to comply with your request of erasure for specific legal reasons which will be notified to you, if applicable, at the time of your request.  

Object to processing of your personal data where we are relying on a legitimate interest (or those of a third party) and there is something about your particular situation which makes you want to object to processing on this ground as you feel it impacts on your fundamental rights and freedoms. You also have the right to object where we are processing your personal data for direct marketing purposes. In some cases, we may demonstrate that we have compelling legitimate grounds to process your information which override your rights and freedoms. 

Request restriction of processing of your personal data. This enables you to ask us to suspend the processing of your personal data in the following scenarios:  

• If you want us to establish the data's accuracy. 
• Where our use of the data is unlawful but you do not want us to erase it.
• Where you need us to hold the data even if we no longer require it as you need it to establish, exercise or defend legal claims.
• You have objected to our use of your data but we need to verify whether we have overriding legitimate grounds to use it.

Request the transfer of your personal data to you or to a third party. We will provide to you, or a third party you have chosen, your personal data in a structured, commonly used, machine-readable format. Note that this right only applies to automated information which you initially provided consent for us to use or where we used the information to perform a contract with you.  

Withdraw consent at any time where we are relying on consent to process your personal data. However, this will not affect the lawfulness of any processing carried out before you withdraw your consent. If you withdraw your consent, we may not be able to provide certain products or services to you. We will advise you if this is the case at the time you withdraw your consent. 

As the statutory harbour authority, licensing authority and owner of the bed of the tidal Thames, the Port of London Authority (PLA) is committed to fostering the sustainable development and management of the estuary in accordance with the Government's Marine Policy Statement, environmental duties under the Harbours Act 1964, and the principles outlined in the Port Marine Safety Code and its associated Guide to Good Practice. 

We will strive to maintain the highest standards of marine safety and environmental stewardship while minimising our environmental impact and deliver the PLA's contributions to the Thames Vision 2050, encompassing the Trading Thames, Destination Thames, and Natural Thames pillars. In pursuit of our mission to maintain the Thames as the UK's number one port, we will proactively comply with environmental legislation, prevent pollution and drive continuous improvements in our operations, which in turn ensures a sustainable and thriving river ecosystem for current and future generations by: 

• Achieving Net Zero by 2040: Commit to achieving net zero emissions for our operations by 2040 through proactive measures that reduce air emissions, decrease energy consumption, enhance energy efficiency, increase our reliance on renewable energy sources, improve waste management and sequester carbon in our landholdings. 

• Implement Climate Adaptation Strategies: Develop and implement comprehensive climate adaptation strategies to enhance resilience against climate change impacts, regularly assess risks, and integrate adaptive measures into our operations.

• Enhance Biodiversity: Manage the PLA estate to ensure that biodiversity is maintained or improved where possible. 

• Sustainable Procurement Practices: Pursue efficiencies that reduce the PLA’s environmental impact by adopting sustainable procurement practices. 

• Prevent pollution: Proactively implement and maintain effective pollution prevention measures throughout operations to minimize environmental impact and ensure a high level of preparedness for potential incidents, taking prompt action when necessary, and collaborating closely with stakeholders

The Port of London Authority (PLA) is committed to taking collaborative action with stakeholders across the port sector to create cleaner air, build Climate Resilience, improve water quality and increase biodiversity. 

The PLA will communicate this environmental policy to all staff, contractors, suppliers and stakeholders. Provide guidance and appropriate training where necessary, and report on our environmental and sustainability performance frequently. In maintaining an Environmental Management System (EMS) under 14001:2015, we will continually improve, assess the impacts of our activities on the environment and monitor and audit their effectiveness. This policy was approved by the PLA Executive Committee in January 2025. 

Chief Executive 

Robin Mortimer

3. Introduction

Alternative diesel fuels have been widely used at a commercial scale in road transport, but there is still relatively limited operational experience with their use in vessel engines to allow the PLA to make an informed decision on which alternative fuel to switch to. Therefore, the PLA had undertaken trials on Gas-To-Liquid (GTL) and Hydrotreated Vegetable Oil (HVO) on one of the Harbour Service vessels, Kew (see Section 3.1 for details), to better understand the environmental benefits relative to Ultra-Low-Sulphur Diesel (ULSD) and to identify if there are any unintended consequences.

To evaluate the air emissions reduction in a maritime setting, the PLA had commissioned University College London to compare the pollutant concentration within the exhaust gas during the operation with neat ULSD, neat GTL, and neat HVO (see Section 3.2-3.5 for the brief description of the fuels). A post-trial engine inspection was also carried out by the PLA’s engineers to ensure there are no unintended consequences to the state of the engines.

A use case that based on the average annual usage of the Kew and the fuel consumption rate of each fuels was also established to appraise the potential air and greenhouse gas emissions saving of the alternative diesel fuels.

3.1 Vessel Specifications & Profile

The PLA’s Harbour Service vessel, Kew, is 13.5 m long, 4.8 m wide with a weight of 11 tonnes and has two Tier II marine diesel engines, John Deere 6068TFM75 6.8 Litre Straight 6 marinesed engines producing 201 hp at 2600 rpm. They are keel cooled and have dry exhausts and each engine has an independent fuel tank. The fuel system for each engine has a Racor 30 micron external fuel filter followed by the engines 30 micron primary fuel filter. This is finally followed by an oil and water separator.

Kew is used in the middle and lower districts of the tidal Thames, between Putney Bridge and the North Sea, to provide regular patrol. The vessel can achieve top speeds of around 20 knots. The typical annual operational profile is as listed in Table 2.

3.2 Ultra-Low-Sulphur Diesel (ULSD)

Sulphur is a naturally occurring component of crude oil, including diesel, and sulphur dioxide (SO₂) or sulphur particulate matter are emitted when the fuels are burned. The Ultra-Low-Sulphur Diesel (ULSD) is a diesel fuel that has been refined so that its sulphur content is 15 part per million (ppm, equivalent to mg/kg) or less.1 The European Fuel Quality Directive (2009/30/EC) stated as of 1st January 2011, all gas oil for use in all non-road mobile machinery, including inland waterway vessels, must contain no more than 10 ppm of sulphur.2 To be compliant with the legislation, Kew had been running on ULSD before the start of the trials of alternative diesel fuel.

The lower amount of sulphur in diesel fuel can reduce the emissions of SO₂ and sulphur particulate matter. However, the emissions of other air pollutants, such as NO_x and other aromatic particulate matter, cannot be reduced without any other post-combustion abatement interventions, such as selective catalytic reduction (SCR) or diesel particulate filter (DPF).

3.3 Gas-To-Liquid (GTL)

The GTL fuel is a synthetic oil derived from natural gas, a type of fossil energy source, but have distinctly different characteristics than the traditional diesel fuel. The GTL fuel has a paraffinic nature, high cetane number, low amounts of total aromatic and sulphur content compared to traditional diesel fuel (Table 3), which have the potential to reduce the emissions of PM. The higher cetane number also leads towards improved combustion that might result in lower carbon monoxide (CO) and Total Hydrocarbon (THC) emissions.3,4

It is colourless, odourless, non-toxic, and biodegradable that it can be packaged, transported, and stored using the same equipment, materials, and procedures as conventional diesel. It also exhibits the flexibility to use as a direct fuel or in blends with fossil fuel which allows seamless introduction without major engine modifications or a new engine or refuelling infrastructure. Due to the potential of lower emissions compared to traditional diesel fuel, it is regarded as a clean alternative fuel.

3.4 Hydrotreated Vegetable Oil (HVO)

Hydrotreated Vegetable Oils (HVO), a type of biofuel and commonly referred to as renewable diesel, is produced from vegetable and/or animal oils and fats through hydro processing.5 The feedstock for HVO is flexible, allowing the use of a wide range of low quality waste and residue materials, such as food waste and oil removed from wastewater sewers (also known as brown grease), for fuel production. HVO produced from waste is considered to have zero-life cycle greenhouse gas (GHG) emissions up to the process of collection of the materials can typically save 88% of the life cycle GHG emission1 relative to diesel fuel.2 The HVO fuel produced from vegetable oil, such as rapeseed, sunflower, and palm oil, can have a typical life cycle greenhouse gas emission savings between 40%-68% relative to diesel fuel2 due to the capture of carbon dioxide during the growth of the plant. However, the other key additional feedstock needed for HVO production is hydrogen, which today comes mainly from a fossil source.5

The HVO fuel has similar fuel properties as the GTL fuel (Table 3) that it also has the potential of reducing the emissions of PM, CO, and THC. Some HVO fuels on the market contain an additive system, which aids to reduce the emissions of air pollutants chemically and cleaner combustion.6 Among other components, the additive package includes a detergent that could potentially cleans the fuel system, valves and injectors.

The HVO fuel also exhibits the flexibility to use as a drop-in replacement for traditional diesel fuel that it can be used without needing engine and infrastructure modifications. The unsaturation and contaminants were removed during production that it is has better storage stability5 and relatively long shelf life.7

3.5 Blend with Diesel Fuel

The alternative diesel fuel trials on Kew did not include blended fuels, however, it is possible to blend in any desired ratio of GTL or HVO into diesel fuels without compromising fuel quality and engine modification.8 Fuel Quality Directive 2009/30/EC (recital 33) states that limit for the content of biodiesel is not required for diesel-like hydrocarbon biofuels and HVO.

Laboratory and land-based studies shown the GTL-diesel or GTL-biodiesel-diesel mixture resulted in a decrease in CO, PM, THC, and SO₂ emissions compared to that for diesel.9,10,11 The results for NO_x emissions from the blended fuel were inconsistent. In general, except for NO_x, the reduction in emissions increases with the increase in percentage of GTL or biodiesel, however, it is uncertain that the improvement is correlated linearly with the content of the alternative fuel or not.

For the HVO-diesel blend, some studies shown the HVO blend resulted in CO, PM, and THC reduction compared to that for diesel,12,13 however, some studies shown the HVO blends did not lead to any reduction in regulated emissions.14

5. Exhaust Emissions Results

5.1 Exhaust Concentration of CO₂

The levels of CO₂ in the exhaust gas samples, representing the CO₂ emitted through combustion, during operation with GTL are consistently appreciably lower than that with ULSD, and HVO at engine speeds above 800 rpm. The emissions of CO₂ from the pipeline are positively correlated with the amount of fuel burnt, and therefore, the results suggest the fuel flow rates were lower and thus engine load produced during the operation with GTL in compare to with ULSD or HVO despite the equivalent engine speed.

The comparable CO₂ emissions during operation with HVO and ULSD at all engine speed suggest similar levels of work produced. The range of CO₂ emissions reduction from the combustion of HVO relative to ULSD found in this study also in agreement with the CO₂ conversion factors used by the UK government,16 with biofuel conversion factors including an “outside of scopes” CO₂ relating to the CO₂ emitted during combustion that is deemed to be offset by the growth of the biofuel feedstock. The CO₂ conversion factors at the point of combustion is 2.74 kg of CO₂ /L for diesel and 2.36 kg of CO₂ /L for biofuel.16

5.2 Exhaust Concentration of NO_x

In general, the levels of NO_x emitted increase with increasing engine speed, especially apparent during operation with ULSD and HVO. A lower NO_x concentration during combustion of GTL and HVO relative to ULSD at all engine speeds were observed. The emission of NO_x increases rapidly with increasing in-cylinder temperature. A higher engine load is likely to have increased in-cylinder temperature, yet, the total level of NO_x produced will have been tempered by the shorter duration at these higher temperatures per combustion cycle with the increase in engine speeds.

In the case of the GTL fuel, this is likely primarily attributable to the lower levels of engine work produced during operation with GTL, as mentioned in Section 5.1. The lower level of fuel burnt resulting in lower in-cylinder temperatures, which reduced the production of NO_x. Other experimental studies9 have found a decrease in NO_x emissions with GTL compared to those from diesel fuel running, attributable to the higher cetane number of GTL fuel and subsequently a shorter ignition delay. However, the magnitude of the reduction depends on engine load and fuel injection conditions.

For HVO, the emissions of NO_x were generally found to be reduced relative to diesel by other combustion studies under laboratory and vehicle testing conditions.17 Nevertheless, the magnitude of reduction is significantly sensitivity to fuel injection timing and other engine operating conditions.

5.3 Exhaust Concentration of PM

The emissions of PM were significantly lower at all engine speeds during operation with GTL and HVO relative to ULSD. The rate of particulate formation during combustion can be increased by the presence of aromatic molecules within the fuel, as these are the precursors to the formation of initial soot particles. The total aromatics content was not stated for the ULSD; however, the level of PAH is higher than the total aromatics content of the GTL and HVO fuels.

The formation and emission of particulates are also sensitive to the fuel air ratio during combustion, with leaner mixtures reducing soot formation and increasing rates of oxidation. In the case of GTL, the significantly lower PM emissions may in part be attributable to the suggested lower fuel flow at a given engine speed. For HVO, there is no apparent suggestion of a lower engine load relative to ULSD and the reduction likely attributable to the fuel chemical properties.

5.4 Exhaust Concentration of THC

The emissions of THC arise due to incomplete fuel combustion, arising from either insufficient temperatures or levels of oxygen. The increasing engines speeds can be expected to reduce the occurrence of both, with higher levels of energy release and reduced time available for fuel over-dilution.

In general, the emissions of THC decrease with increasing engine speed when operation with ULSD or GTL, and lower THC emissions at a given speed in the case of operation with GTL or HVO relative to that with ULSD. The significantly higher cetane number of the GTL and HVO fuel relative to ULSD would likely have reduced the duration of fuel ignition delay following the start of injection and decreased the time available for fuel over-dilution prior to the start of combination that reduces the production of THC relative to ULSD. Notwithstanding the cetane number is the same for HVO and GTL, the influence of engine speed in THC emissions in operation with HVO were not clear.

5.5 Exhaust Concentration of CO

Similar to the formation of THC, emissions of carbon monoxide (CO) arise due to incomplete combustion of fuel carbon, and so might be expected to reduce with increase engine speeds.

The levels of CO emitted show a general decrease with increasing engine speed when operating with ULSD or GTL fuel. The lower levels of CO emitted in the case of operation with GTL relative to ULSD and HVO at all engine speeds greater than 800 rpm is consistent with the suggestion in Section 5.1 that the fuel flow rates, and engine loads were lower during operation with GTL.

In contrast to ULSD and GTL, the highest levels of exhaust CO during operation with HVO were found at the highest engine speed of 2500 rpm. The higher levels of CO observed with HVO are in agreement with the lower emissions of NO_x as shown in Section 5.2, which both indicate the lower in-cylinder temperatures in the case of HVO combustion.

5.6 Uncertainties in the Exhaust Monitoring

The exhaust samples were collected on dedicated sampling cruise with the same route but on different day and time. The effects of tide and weather conditions were not considered for the exhaust sampling analysis, which might affect the engine load and fuel consumption, and hence, the emissions.

7. Use Case Result

7.1 Annual Air Pollutant Emissions

The estimated annual emissions of NO_x, PM, and THC is shown in Table 5. The emissions of PM are significantly lower with the use of alternative fuels. The emissions of NO_x are almost halved for GTL and almost a third for HVO.

7.2 Annual Greenhouse Gas Emissions

The scope 1 CO₂e and the “outside of scope” CO₂ emissions are listed in Table 6. The scope 1 CO₂e is significantly lower with the use of HVO relative to ULSD due the uptake of CO₂ during the growth of the plant or organic waste being used as feedstock. No CO₂e or CO₂ values were calculated for GTL as there is no conversion factor available. However, as mentioned in the Introduction that the feedstock of GTL is natural gas, a type of fossil fuel.

References

1 European Commission, “Alternative Fuels for Marine and Inland Waterways; An exploratory Study (Report EUR 27770 EN),” European Union, EUR, 2016.

2 European Parliament and of the Council of 23 April 2009, Directive 2009/30/EC, Special edition in Croatian: Chapter 13 Volume 055 P. 187 - 212, Current consolidated version: 10/06/2016.

3 M. Oguma, S. Goto, K. Oyama, K. Sugiyama and i. M. Mor, “The Possibility of Gas to Liquid (GTL) as a Fuel of Direct Injection Diesel Engine.,” SAE Technical Paper 2002-01-1706, 2002.

4 M. Lapuerta, O. Armas, J. Hernández and A. Tsolakis, “Potential for reducing emissions in a diesel engine by fuelling with conventional biodiesel and Fischer–Tropsch diesel.,” fUEL, vol. 89, pp. 3106-13, 2010.

5 European Alternative Fuel Observatory, “Hydrotreated Vegetable Oils (HVO),” European Alternative Fuel Observatory, [Online]. Available: https://eafo.eu/alternative-fuels/advanced-biofuels/hvo. [Accessed 3 2021].

6 New Era, “GreenD+ HVO,” New Era, [Online]. Available: https://newerafuels.co.uk/green-d-hvo/. [Accessed 3 2021].

7 Crown Oil, “HVO Fuel (Hydrotreated Vegetable Oil Fuel),” Crown Oil, [Online]. Available at this link. [Accessed 3 2021].

8 Y. Huang, S. Wang and L. Zhou, “Effects of Fischer-Tropsch diesel fuel on combusion and emissions of direct injection diesel engine,” Frontier of Energy and Power Engineering in China, vol. 2, no. 3, pp. 261-267, 2008.

9 H. Sajjad et al., “Engine combustion, performance and emission characteristics of gas to liquid (GTL) fuels and its blends with diesel and bio-diesel,” Renewable and Sustainable Energy Reviews, 2014.

10 M. Gunfeel, Y. Lee, K. Choi and D. Jeong, “Emission characteristics of diesel, gas to liquid, and biodiesel-blended fuels in a diesel engine for passenger cars,” Fuel, vol. 89, no. 12, pp. 3840-3846, 2010.

11 M. Bassiony, A. Ibrahim and M. El-Kassaby, “An experimental study on the effect of using gas-to-liquid (GTL) fuel on diesel engine performance and emissions,” Alexandria Engineeering Journal, vol. 55, no. 3, pp. 2115-2124, 2016.

12 L. Rantanen, R. Linnaila, P. Aakko and T. Harju, “NExBTL - Biodiesel Fuel of the Second Generation,” SAE Technical Paper 2005-01-3771, 2005.

13 D. Athanasios, N. Ioannis, D. Athanasios, K. Dimitrios, S. Zissis, B. Stella and L. Kalle, “Evaluation of a Hydrotreated Vegetable Oil (HVO) and Effects on Emissions of a Passenger Car Diesel Engine,” Frontiers in Mechanical Engineering , vol. 4, no. 7, pp. 2297-3079, 2018.

14 R. Suarez-Bertoa, M. Kousoulidou, M. Clairotte, B. Giechaskiel, J. Nuottimäki, T. Sarjovaara and L. Lonzaa, “Impact of HVO blends on modern diesel passenger cars emissions during real world operation,” Fuel, vol. 235, pp. 1427 - 1435, 2019.

15 Neste Oil, “Hydrotreated Vegetable Oil (HVO) - premium renewable biofuel for diesel engines,” Neste Oil Proprietary publication, 2014.

16 Department for Business, Energy & Industrial Strategy, “Government conversion factors for company reporting of greenhouse gas emissions,” Gov.uk, 2021 6 2020. [Online]. Available at this link. [Accessed 3 2021].

17 S. Y. No, “Application of hydrotreated vegetable oil from triglyceride based biomass to CI engines - a review,” Fuel, vol. 115, pp. 88-96, 2014.