Perspectives of a Sustainable Future Based on LPG and Renewable BioLPG as Fuel Suppliers: New Developments and Existing Barriers

Abstract

This chapter provides an overview on the outstanding production, distribution and storage technologies that will likely make the liquefied petroleum gas (LPG) and renewable BioLPG expand their utilization as a cleaner alternative to traditional fossil fuels. The growth of the Global LPG Market size will be presented, with a focus on US and the Europe, the Middle East and Africa (EMEA) regions. Moreover, the increment of worldwide policies aimed at reducing greenhouse gas emissions (GHGs) will be investigated. The growth of the LPG market is primarily propelled by the rising demand for a cost-effective and environmentally sustainable substitute of conventional fossil fuels. Concerning the residential sector, the demand for LPG is due to such end-uses as cooking, water heating and other household purposes. Regarding transportation, LPG’s popularity as an alternative automotive fuel (auto-gas) has also contributed significantly to its widespread adoption in this sector. On the other hand, the utilization of BioLPG is also going up since it is chemically indistinct from LPG and so, it can be ‘dropped-in’ to existing LPG boilers and appliances. Finally, the existing barriers and the new developments on this topic will be investigated to understand why LPG and BioLPG could represent a great investment for the future.

1. Introduction

In a world grappling with the challenges of global warming and climate change, liquefied petroleum gas (LPG) is gaining popularity as a clean and sustainable alternative source to carbon fossil fuels. Primarily composed of propane and butane [1], LPG offers a cleaner burning alternative to traditional fossil fuels, such as coal and oil [2]. It is due to the fact that, when ignited, LPG emits significantly lower levels of harmful pollutants, including carbon dioxide (CO₂), nitrogen oxides (NOx) and particulate matter (PM). Now, according to the World LPG Association (WLPGA) [3], LPG emits up to 15% less CO₂ than coal and 30% less than oil when used for heating and cooking purposes. This is because LPG produces less CO₂ emissions overall. Compared to gasoline, previous studies have demonstrated that LPG produces, respectively, 69.94%, 46.48%, and 47.89% lower hydrocarbon (HC), NOx and carbon monoxide CO emissions. The lower HC emissions have been demonstrated to be due to the higher flame’s propagation speed and combustion temperature of LPG [4, 5].

Furthermore, the impact that LPG has on air pollution is far lower than natural gas when used in spark-ignited engines. Previous comparative studies showed as direct consequence of its considerably higher methane (CH₄) emissions that compressed natural gas generates a 10% and 4% higher brake-specific carbon dioxide equivalent (bsCO₂eq) at low engine loads than LPG. Moreover, LPG fuel consumption is lower when producing the same amount of energy, as it has a higher energy content compared to natural gas [6]. Indeed, the European Commission approved a long-term strategy for driving EU towards a net-zero GHG economy with the target of reducing emissions by 80–95% in 2050. As part of the European Green Deal, the Commission proposed on 4 March 2020 the first European Climate Law to enshrine the 2050 climate-neutrality target into law [7].

In summary: the worldwide awareness that reduction in greenhouse gas emissions plays a vital role in mitigating climate change and improving air quality has driven LPG to be considered a crucial tool in the fight against global warming. Therefore, LPG is a perfect candidate to be the clean alternative to petroleum in the medium term for the transition to sustainable fuels and transport [8].

1.1 BioLPG, the renewable and sustainable form of LPG

Some studies, such as Ref. [9], showed how switching fuels to LPG in the immediate term and, progressively, to BioLPG as a direct replacement fuel, can contribute to establish pathway towards decarbonization for industrial and commercial businesses. BioLPG is a renewable and sustainable form of LPG derived from organic waste materials, agricultural residues and other biomass sources with a carbon intensity of around 70–80%, which is lower than that for oil. It is also called renewable propane and biopropane, as it can reduce the carbon footprint and CO₂ emissions up to 80% [10].

BioLPG can be produced in several ways depending on the feedstock and processes used. In Figure 1, the main process currently in use, together with their technology readiness level (TRL), is presented.

Figure 1.

Feedstocks and processes for biofuel production. Source: Liquid Gas UK [11].

As it can been seen from Figure 1, among all promising production processes, hydroprocessing of vegetable oils (HVO) is the most mature one and, currently, it is the main production route for biopropane, able to produce (via HVO and fats) significant volume of HVO BioLPG with a process performance in the range of 5–8% [11]. Therefore, there is still significant work ahead to implement and test novel technologies able to produce BioLPG at commercial scale and at affordable costs to end users [10].

The growing interest in BioLPG as renewable fuel can be attributed to the following factors: First, BioLPG is produced by renewable crops grown and waste feed stocks, which made it an ideal energy solution to meet the EU sustainable goals and enable the transition to a circular economy. On the other hand, BioLPG offers similar performance and efficiency as conventional LPG as both are chemically identical. Consequently, it is compatible with all LPG applications and it can be blended and used by all existing LPG equipment without significant modifications. Moreover, BioLPG offers the same benefits as conventional LPG in terms of high quality, low-carbon fuel with reduced emissions and improved air quality, but with the added advantage of being renewable and carbon neutral. Furthermore, the growing concerns about greenhouse gas emissions resulted worldwide in the implementation of supportive policies and incentives to encourage the adoption of cleaner fuels as in the UK, where Liquid Gas UK (LGUK) has proposed BioLPG as a potential solution to satisfy residual gas needs for off-grid heating to reduce carbon emissions [12]. These initiatives, coupled with the increasing availability and affordability of BioLPG, have contributed to the rise of its use among industries, households and the transportation sector [13].

2. Current trends of the LPG market in US and EMEA regions

Liquefied petroleum gas, together with its eco-friendly sibling, BioLPG, is playing a crucial role in reducing greenhouse emissions. To understand what delves into the reasons behind the growing popularity of LPG and BioLPG as a competitive clean fuel, it is important to be aware of the market trends.

Especially in developing countries, LPG has the prevalent usage as household fuel [14]. Such countries as India, Indonesia, Morocco or some South American nations still rely on LPG on a daily basis, while others like some countries in Africa aim to increase household LPG use up to 80% by 2030 [9].

The recent trend in LPG consumption worldwide shows that, on average, it is equal to 54.28 thousand barrels per day (picture from 2021) based on the data belonging to 185 countries. The country with the major consumption of LPG in 2021 was China with 2258.97 thousand barrels per day, followed by the USA with 1374.98 thousand barrels per day [15]. Table 1 shows the Top 10 global countries’ worldwide LPG consumption in 2021 (values are expressed in thousand barrels per day).

Global rank	Countries	LPG consumption, 2021; (thousand barrels per day)
1	China	2258.97
2	USA	1374.98
3	India	886.55
4	Russia	802.34
5	Saudi Arabia	494.83
6	Japan	404.53
7	South Korea	299.92
8	Mexico	278.86
9	Indonesia	271.86
10	Thailand	194.80

Table 1.

Top 10 global countries’ worldwide LPG consumption in 2021 [15].

2.1 LPG market in the USA

In the USA, LPG is predominantly used for commercial and domestic use, heating or cooking, followed by chemical industry where the LPG’s largest market is petrochemical feedstock. Moreover, in agriculture industry, LPG is largely used for fueling machinery, livestock-rearing, crop-drying, weed and animal waste disposal. Furthermore, it is also used as an engine fuel alternatively to gasoline and as a stand-by fuel for facilities that have interruptible natural gas service contracts [16]. The U.S. field production of propane increased in the past decade and it is forecasted to rise by another 5% in 2024. Altogether, the use of LPG for residential and commercial heating purposes has witnessed an increase of 20%, as shown in Figure 2.

Figure 2.

U.S. field production of propane in thousand barrels. Source: EIA.

Furthermore, the USA is the largest LPG exporter in the world. LPG exports reached 14.5 million tonnes of seaborne volume in the second quarter of 2023, the highest quarterly total ever to reach a peak of about 1.7 million barrels per day (b/d) exported in March 2023 (see Figure 3).

Figure 3.

Monthly U.S. propane exports by destination region—January 2004-March 2023. Source: Environmental Impact Assessment (EIA).

2.2 LPG market in Europe

In Europe, the versatility of LPG as fuel that can be easily liquefied and stored in multiple ways allowed its use in different sectors, such as space and water heating, cooking, lighting, power generation, industrial processing, and heating and automotive fueling.

In 2023, Europe’s LPG demand stood at 46.79 million tonnes and it is forecasted to reach the 77.68 million tonnes roughly in 2032 [17]. The aviation industry and its use for domestic cooking are predominant in European regions but the rising consumption of this fuel in the automotive transportation is driving the growth of the LPG market. In fact, auto-gas consumption (as it is called LPG fueled in cars) has increased more than 10% in the past 5 years, with BioLPG accounting for a significant portion of this growth [18].

Vehicle emissions of millions of EU citizens (including cars and vans) have been accounted to be, respectively, for around 12% and 2.5% of the total EU emissions of CO₂, respectively. Therefore, EU governments are promoting initiatives to bolster the use of LPG as retrofit fuel for internal combustion engine vehicles, for large vehicles and fleet management solutions [19].

Liquefied petroleum gas, together with BioLPG, can represent a green alternative to fossil fuels to meet the EU sustainable targets, especially in urban areas. The 2003 European Emission Testing Program (EETP) demonstrated that LPG-fueled vehicles are 120–180% better than petrol and 2000% better than diesel in terms of NOx. Moreover, it is 99% better than diesel in terms of particle emissions what is the clear advantage of its use [20].

Recent issues, like COVID-19 and Ukraine war, highlighted the need for building reliable coordinating measures to secure energy supply. The Directive 2009/119/EC requires EU Member States to maintain minimum stocks of crude oil and/or petroleum products. Likewise, the membership obligations of the International Energy Agency (IEA) include maintaining oil reserves equivalent to 90 days of net imports [21]. Moreover, the Russian conflict pinpoints the potential of LPG as natural gas substitute in case of disruption due to their physical similarity and compatibility with the existing infrastructure. In this framework, EU self-sufficiency can be promoted by adopting LPG for three main reasons: due to its large availability, the overall balance in EU consumption and production and the geographical diversifications of the imports [20].

As it is well known, LPG can be derived from a plurality of sources such as crude oil and natural gas, and its possible production from biomass (BioLPG), which has lately attracted government attention worldwide. Commonly transported as liquid in different ways, among its advantages there is the fact that it does not rely completely on a fixed reticulated and pipeline infrastructure as it happens with natural gas. Rather, it can be transported by using a combination of ways, like ships, road tankers and tanker rail cars. These suitable characteristics, together with extensive availability of LPG and its flexible and decentralized distribution network (as shown in Figure 4), enable its use in rural and isolated areas that are not served by other energy fuels.

Figure 4.

Map of the LPG industry and distribution. Source: European Commission Joint Research Centre (JRC) [22].

The LPG industry allows import, storage and pressurized transport of LPG everywhere and it is especially significant in areas that are not served by the natural gas distribution infrastructure. Accordingly, Figure 4 shows the LPG supply chain from the production site at refinery or gas receiving terminals to the end user. LPG can be imported by pipeline, rail and road or can be containerized. The bulk of storage can be refrigerated at atmospheric pressure with a temperature of −43°C or pressurized at ambient temperature with a pressure from 4.0 to 13.0 bar. Domestic distribution of LPG also takes place by road transport, rail, pipelines or ISO (International Organization for Standardization) container on road or by sea.

Regarding the LPG consumption, European countries (based on 27 countries) consumed 29.71 thousand barrels per day in 2021, as shown in Figure 5. The highest value was for Germany, with 116.56 thousand barrels per day, while the lowest value was for Luxembourg with 0.33 thousand barrels per day. Only a few European countries have included LPG in their energy mix. Germany, France and Italy have strongly embraced LPG usage. The reason why Germany and France decided to rely on LPG, mainly for the automotive sector, which resides on their market trend that is less affected by prices of inflation (like gasoline) and, consequently, LPG results as a convenient, alternative fuel [23]. Moreover, the tough rise of gas price has stressed this tendency and prompted many refineries to switch to LPG as a cheaper alternative. In Italy, LPG usage has grown in the last years due to a strategic decision of adopting BioLPG as a renewable fuel before shifting to electric car or heat pump. Nowadays, BioLPG consumption has reached the 50% in the automotive sector, 25% for heating and cooking and the remaining by the industrial process. Italy is trying to increase LPG production, especially BioLPG, from organic sources, which is expected to reach the 5 million metric tonnes/year by 2030 [3].

Figure 5.

Liquefied petroleum gas consumption (2021), in thousand barrels per day. Source: Environmental Impact Assessment (EIA).

The EU production is slightly lower than the demand, needing a 6% of LPG net import from abroad (Figure 6) but LPG supply is expected to exceed by far the projected demand by 2030 [24].

Figure 6.

Supply vs. demand European LPG (thousands of tonnes). Source: World LPG Association (WLPGA).

In Europe, the existence of a highly fluid international trading market guarantees that LPG imports are geographically diversified. Figure 7 shows the geographical diversification of the European LPG imports, as well as the export terminal locations. In the first 10 months of 2022, the European Union significantly increased its seaborne imports of LPG from the United States, reaching 6.4 million metric tonnes between January and October 2022, which represents almost twice the same period in 2021 [24].

Figure 7.

Key European LPG import and export terminal locations. Source: World LPG Association (WLPGA).

The current growth of the LPG market is mainly propelled by the rising demand of a cost-effective and environmentally sustainable substitute for conventional fossil fuels. In this framework, BioLPG is gaining popularity too since it is chemically indistinct from LPG and so, it can be ‘dropped-in’ to existing LPG boilers and appliances. In spite of that, the BioLPG market is still limited and, indeed, if compared with LPG global production, BioLPG production is still less than 0.1% [25]. However, it is expected to grow over 2.2 metric tonnes per year (Mt/yr) by 2030 [9].

3. The role of the LPG and BioLPG towards more sustainable mobility in Europe

Automotive LPG, also known as Autogas, constitutes together with BioLPG a dynamic duo widely used in the EU as alternative to fossil fuel. Benefits of using Autogas are related to its large availability, safety, lower emissions and the lower cost they entail if compared with gasoline and diesel (Figure 8). Studies have demonstrated that Autogas-fueled vehicles emit over 20% less carbon monoxide, 10% less CO₂ and more than 40% less nitrogen oxides than gasoline engines [26]. Moreover, minimum adaptations to the existing infrastructure are required to use LPG, with minimum investment in infrastructure [27].

Figure 8.

Total carbon emissions for various fuels. Source: Alliance AutoGas.

Figure 9 provides an overview of the average Autogas price, showing that it is more convenient, from the economic point of view, than fossil fuels (petrol and diesel). As it can be seen, Autogas is an appealing solution towards the green EU pathways as it is an economic alternative. The large availability of this fuel and the surplus of its supply, able to afford the ensuing growth in the demand together with favorable tax rate established by the EU Directive, are the reasons why LPG is the most promising and economic fuel alternative for the automotive sector’s decarbonization [28].

Figure 9.

Overview of the average pump price in a euro per liter (€/l) (value-added tax (VAT) and exercise duty included) in a selection of EU countries (2013). Source: Oil Bulletin, Directorate-General for Mobility and Transport (DG MOVE), European Commission.

Nowadays, as shown in Figure 10, there are about 8.5 million registered vehicles (new and retrofit passengers’ cars) fueled with LPG in the EU and over 30,700 Autogas filling stations [29]. This increment of about 16% in Autogas vehicles, compared to the previous year, is due to the ongoing energy transition that has identified the automotive sector as responsible for the almost 20% of Europe’s total greenhouse gas emissions (GHGs) [30].

Figure 10.

The total number of alternative fueled passengers’ cars in the EU. Source: Alternative Fuels Observatory [29]. Considered types of cars are: battery electric vehicles (BEVs); plug-in hybrid electric vehicles (PHEVs); vehicles fueled by hydrogen (H₂); liquefied petroleum gas (LPG); compressed natural gas (CNG); and liquefied natural gas (LNG).

Autogas market is well developed worldwide. LPG demand reached about 46.79 million tonnes in 2023, although it is forecast to grow sensibly in the next future reaching 69.89 million tonnes by 2030 [31]. According to the countries where the consumption of Autogas is more significant, just five countries (Turkey, Russia, South Korea, Poland and Ukraine) together accounted for almost a half of the global Autogas consumption in 2021, as shown in Figure 11.

Figure 11.

World Autogas consumption in 2000–2021. Source: World LPG Association (WLPGA)/Argus (2022); International Energy Agency (IEA) databases.

Figure 11 also shows a significant increment of Autogas consumption from 2010 since, in that year, a re-categorization of LPG demand assigned before to the residential sector was produced.

Regarding the USA, Autogas has been used in transportation since 1912 thanks to the California Energy Commission, which encouraged Autogas vehicle conversions and refueling stations. After that, Autogas was declared an alternative fuel under the Energy Policy Act of 1992 [32]. Today in the USA, there are about 155,000 road vehicles powered by Autogas and about 2500 public filling stations with available fuel for use in vehicle distributed on all US territories (Figure 12).

Figure 12.

Propane filling stations’ location by the US state. Source: Alternative Fuels Data Center [33].

Together with the LPG, opportunities for feeding the existing vehicles with BioLPG are also under evaluation in the USA. Renewable propane (BioLPG) obtained using renewable or bio-based feedstock is nowadays used as drop-in replacement fuel for conventional propane [34]. The LPG’s low price, the reduced maintenance cost and the minimum environmental impact, together with the low level of noise pollution, made Autogas engines attractive for urban transportation. In 2014, in the USA, it was estimated that more than 7000 busses for pupil transportation were reconverted to Autogas propane engines [35].

The spread out of federal and state regulations to stimulate Autogas applications has brought about the wide spread of vehicle conversions and the increase in the refueling stations, but the American Autogas market is still small when compared to other automotive fossil fuel markets [36]. The chart in Figure 13 shows the trend in the USA vehicle registration from 2016 up to 2020. Hydrogen fuel cell light-duty vehicles show the greatest growth, reaching the maximum peak in 2019, while the annual change in propane is more volatile as propane vehicles are mostly used for school bus fleets. Electric vehicle registrations had seen a steady growth until 2020, but they grew more than any other light-duty vehicle type between 2021 and 2022 [37].

Figure 13.

Change in US vehicle registration counts. Source: Alternative Fuels Data Center.

The US federal and state regulations and incentives have had a significant impact on the wide spread of LPG-driven vehicles, as evidenced in Figure 14. Tax credits, low-interest loan programmes and tax exemptions adopted by different States reduced the LPG cost of conversion and offered more incremental savings to end users [38]. The introduction of lower fuel tax rates on LPG has resulted in a lower maintenance cost for LPG vehicles than petrol or diesel ones. Moreover, the introduction of the National Energy Policy Act 1992 obliged US citizens to shift to more sustainable fleets fueled by alternative fuels (among them, LPG). In terms of safety, the design and construction of LPG tanks have been regulated by US government agencies and handling protocols have been approved for personnel training [39].

Figure 14.

Propane laws and incentives by state. Source: Alternative Fuels Data Center.

4. Existing barriers and new developments in LPG and BioLPG as fuel for a sustainable future

The adoption of LPG and BioLPG as clean fuel alternatives in Europe and the USA faces several challenges and barriers that need to be addressed.

The growing global awareness and concern about global warming and greenhouse gas emissions have led governments worldwide to implement regulation and subsidies to start a sustainable transition towards alternative and green fuels and, among them, LPG and renewable LPG. Despite that, additional incentives should be established to increase the use of alternative fuels for vehicles and infrastructure. Governments should work closely with fuel providers and fleet managers to offer incentives able to make drivers switch to alternative fuels and increase LPG applications.

Autogas, as alternative fuel for light-duty vehicles in the EU, is facing relevant challenges related to current regulation, which bans the use of internal combustion engines after 2035. Germany weakened the law by introducing an exception for synthetic e-fuels; Italy, Romania and Bulgaria decided to remain neutral and just Poland voted against that legislation. In this context, the European Commission is developing new legal rules for allowing just the sale of cars powered with e-fuels after 2035. Unfortunately, the role of Autogas in this scenario is not clear, as CO₂ neutral fuels are not explicitly identified in the legislation [30].

Additional studies should be carried out to evaluate the emission rate of the existing vehicles fueled with LPG and, especially, BioLPG to demonstrate their low environmental impact and to make grow people’s awareness about the potential benefits in quality of air when using LPG. There are studies ongoing with the purpose of evaluating the benefits of LPG and BioLPG fuels in terms of emissions of secondary organic aerosols (SOA). Moreover, investments in research and development should be done by manufacturers to improve the efficiency of LPG system and reinforce refueling LPG infrastructure for vehicles [34].

Forecast about LPG automotive sector expects a steady growth of the automotive market in the coming years. However, the trend of LPG engine markets is still affected by the impact of inflation on LPG prices. In Europe, the current price policy undertaken by each Member State should be able to mitigate inflation effects on the LPG price, as it is still the driving factor for end users’ fuel choice [40].

Among the new developments, it is interesting to highlight the latest advancements in fuel cell production as eco-friendly power source that extracts hydrogen from LPG. Although hydrogen is commonly produced from natural gas, steam reforming is a technology that can be used to produce hydrogen from other fuels like propane [41].

Manufacturers are exploring new fuel cell technologies and new ways of producing hydrogen by using renewable energies or alternative fuels. Indeed, propane can be a valid alternative due to its low emissions when compared with other existing fuels [42]. Accordingly, different studies have demonstrated the possibility of producing high concentrations of hydrogen from LPG reforming. Actually, during the final state of propane cleavage of the steam reforming, the reaction of oxidative reforming of LPG resulted in a lower coke formation, a higher production of H₂ with a yield value that can vary from 77.5% to 92.2%. On the other side, the most suitable conditions for the process required the use of an excess of water (H₂O/LPG = 7.0) and intermediate temperatures (973 K) [43, 44, 45, 46].

Among the studies focused on the use of propane in different fuel cells, the special suitability of propane for direct fuel cells (DPFCs) has been identified. The two main reasons for propane’s choice as an alternative fuel rely on the fact that infrastructures for direct propane fuel cells are already available in rural areas as propane is still predominantly used there for heating. Moreover, in rural areas, the power price produced by DPFCs is still competitive compared to the one of grid-connected utilities. Furthermore, propane is available everywhere and it can count on a reliable and robust infrastructure, while hydrogen distribution infrastructure is not ready yet. Additionally, the lower cost of propane as fuel for hydrogen production can positively affect the cost of manufacturing hydrogen. Ultimately, hydrogen storage is very expensive while propane can be easily stored and transported [47, 48].

Regarding BioLPG, its use has been tested in automotive applications with positive results and it is widely supported by regulation worldwide. On the contrary, for power generation applications, it is still required to carry out the implementation of subsidiary policies able to incentivize and boost power generation from renewable propane. BioLPG is characterized for lower emissions than conventional diesel; it is practically neutral and it allows a reduction of 3 tonnes of CO₂ for each tonne of BioLPG consumed. In this scenario, the framing of a supportive incentives regulation for LPG power applications can actively contribute to the energy transition and accelerate decarbonization [49].

5. Conclusions

This chapter highlights the advantages of LPG as a sustainable alternative to carbon fossil fuels due, among other benefits, to the lower emissions of CO₂ (15% less than coal and 30% less than oil) and other pollutants. This fact may help reach international commitments assumed by different countries for environmental reasons, such as the target of reducing emissions of the European Commission by 2050. Moreover, the so-called BioLPG (that is a renewable and sustainable form of LPG derived from organic waste and biomass sources) can help to reduce the carbon footprint up to 80%, considering the life cycle of the used materials.

Both LPG and BioLPG are mainly used for residential applications (mainly cooking and space heating) and for mobility issues to fuel cars. The automotive LPG, also known as Autogas, presents several benefits such as large availability, safety, lower cost and lower emissions. In fact, Autogas-fueled vehicles emit over 20% less CO, 10% less CO₂ and 40% less NOx than gasoline engines.

In spite of LPG’s benefits, there are still barriers that prevent the massive utilization and further development of this fuel in terms of sustainability. Many of them are regulatory since the role of LPG in the framework of future clean energy supply has not been clearly stated, with a lack of regulation existing in that direction to promote the utilization of this fuel in the short term. In the automotive area, one of the most promising future applications of LPG is the obtaining of hydrogen to be used in combustion engines or fuel cells. In summary: Properties of LPG and its variants (BioLPG and Autogas) make a good solution to accelerate decarbonization and contribute to the energy transition for a future cleaner and sustainable energy production.