Energy demand and consumption are anticipated to rise, particularly for fossil fuels ^[1][2][3][1,2,3]. Fossil fuels, often referred to as traditional energy, are extensively used in India’s automobiles and industrial facilities ^[4][5][4,5]. Plastic consumption went from 4000 tonnes per year in 1990 to 4 million tonnes per year in 2001 and is projected to escalate by 3.5–4 lakh million tonnes per year by 2022 ^[6][7][6,7]. After they have served their purpose, items made of plastic are thrown away. Biological breakdown is not possible with these materials ^[8][9][8,9].

Consequently, they are either buried or burned [10]. These processes pollute the air and the land, making them not eco-friendly. Tyres and waste plastic are classified as hazardous or solid waste in India ^[11][12][11,12]. About 60% of (retreated) waste tyres are thought to be disposed of in both urban and rural areas via unidentified routes ^[13][14][13,14]. The risks associated with waste tyres include air pollution brought on by the open burning of plastic, aesthetic pollution brought on by the accumulation of waste plastic, illegal waste collection, and additional effects such as changes to hydrological regimes when gullies and watercourses turn into dump sites ^[15][16][17][15,16,17], as shown in Figure 1.

Most waste comprises thermoplastic polymers, and this percentage is steadily rising globally ^[18][19][18,19]. Therefore, waste plastics present a severe environmental challenge due to their enormous quantity and disposal issues because thermoplastics take a very long time to biodegrade ^[20][21][20,21]. The conclusion drawn from every line of reasoning and argument in favour of and against plastics is that it is not biodegradable [22]. Several different kinds of research have been done regarding the disposal and decomposition of plastics [23]. Currently, disposal techniques are used in landfills and mechanical, biological, thermal, and chemical recycling. Chemical recycling is one of these methods, and it’s a research area that’s recently attracted much attention because the products that come from it are beneficial.

In India, there are currently no substantial alternative energy sources ^[24][28]. Moreover, it imports more than 49% of its energy requirement, owing to its inability to fulfil energy demand in 2017. In 2016 and 2017, the price of imported crude oil and petroleum products climbed by 39.8% and 23.0%, respectively, due to Thailand’s growing oil consumption ^[25][26][29,30]. Thailand has purchased chiefly crude oil from countries in the Middle East. It is predicted that the use of renewable energy in Thailand will gradually climb. It has been proposed that oil produced from recycled plastic is utilised as an alternative fuel for automobiles to increase this proportion while decreasing the quantity of primary energy consumed. This programme moves toward fuel diversification via energy conversion technologies, notwithstanding the declining need for energy in the transportation sector. In addition, it focuses on the use of oil derived from discarded plastic in diesel engines.

There is much plastic garbage because factories and homes produce too much waste. These wastes are difficult to handle and take hundreds of years to decompose. Only 2% of chemicals are recycled, compared to the majority of plastic, which is recycled mechanically ^[27][28][31,32]. In general, the landfill method of waste management is currently in vogue ^[29][33]. This method typically necessitates a large amount of landfill space and affects the environment, causing soil pollution.

Plastic garbage contains hydrocarbons, the main constituent of conventional fuels ^[30][34]. By converting plastic trash into fuel, the possibility of recycling improves. Products may be acquired from the manufacturing process and utilised as an energy source equivalent to traditional fuels. In terms of waste management, it may also improve the environment by minimising the challenge of locating landfill sites, thus reducing the quantity of plastic trash created and lowering the cost of plastic waste disposal. The diverse plastic compositions affect various sorts of plastics as well. Recent research found that the combination of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) in oil products has a higher heating value than the use of LDPE, polypropylene (PP), or HDPE by themselves. The most excellent yields were determined to be LDPE ^[31][35]. Oil from recycled plastic-powered engines was also tested, and it was discovered that there was almost no variation between it and diesel fuel ^[32][36]. The thermal efficiency of waste plastic oil was significantly higher when compared to that of diesel fuel ^[33][34][37,38].

Kalargaris et al. investigated the exhaust emissions of a diesel engine with 4 cylinders and direct injection. It uses diesel mixed with varying amounts of waste plastic oil, increasing ignition delay and nitrogen oxide emissions ^[35][39]. There were more hydrocarbon emissions than with diesel fuel ^[36][40]. These findings contradict the findings of another study that observed the exhaust emissions of a diesel engine with 4 cylinders and direct injection.

Biodiesel is expected to become a green energy source in energy mobility. Much research has supported using biodiesel as a viable substitute for diesel fuel. It is envisaged that the presence of oxygen in fuel molecules will result in cleaner biodiesel combustion and lower emissions. On the other hand, there are not an excessive number of reports involving biodiesel that has been combined with used plastic oil. For instance, Ramesha et al. discovered that a B20 mixture of algae biodiesel fuel and waste plastic oil might be utilised as fuel for diesel engines when blended together ^[37][41].

The oil from the waste plastic–biodiesel combination displayed 16% greater braking thermal efficiency than diesel engines. Furthermore, nitrogen oxide emissions increased slightly compared to diesel, while hydrocarbon and carbon monoxide emissions decreased. Senthilkumar et al. examined recycled plastic oil in diesel engines in conjunction with Jatropha biodiesel and observed that the waste plastic oil–biodiesel combination had higher brake thermal efficiency and brake-specific fuel consumption than oil from waste plastic ^[38][42]. When waste plastic oil and Jatropha biodiesel were combined, the emissions of hydrocarbons and carbon monoxide were reduced ^[39][40][43,44]. Without modifying the engine, waste plastic oil–biodiesel blends were used in the current researchtudy as an alternative fuel in a diesel engine. Castor and palm oils were blended with old plastic oil after transesterification and utilised to make the biodiesels that were ultimately selected ^[41][42][45,46]. The palm tree is a critical commercial crop in Thailand and the principal feedstock utilised in biodiesel production. Due to its substantial oxygen content in fuel molecules and outstanding fuel lubricity, castor oil was a viable alternative to edible feedstock ^[43][44][47,48]. Regarding the emissions produced, the oxygen in the fuel molecules assists in boosting the combustion processes. In this rpapesearch, the researchers r, we investigated the impact of mixing bio-diesel with oil from recycled plastic on the resulting fuel mixture’s fundamental physical and chemical fuel properties. The primary areas of the researchers'our investigation were the performance, combustion characteristics, and exhaust gas emissions of a diesel engine with a single cylinder. During the engine test for the combustion characteristics part, basic measures such as in-cylinder pressure and crank angle were logged. These data were used to evaluate the engine’s performance. The first rule of thermodynamics’ mathematical underpinnings was then used to calculate the rate at which the test fuels released heat. The specific heat ratio (SHR) was estimated using the in-cylinder pressure and the combustion chamber volume under the assumption that there was a polytropic process ^[45][49].

According to the observations of Machiraju et al., pyrolysis with a catalyst can produce a fuel with chemical properties similar to conventional fuels ^[46][50]. Observations indicate that pyrolysis is a feasible and economical process. The processing of one kilogramme of trash plastic results in the production of 0.75 kilogrammes of usable liquid fuel, all without releasing any contaminants and toxins. Along with the reduction in crude oil imports, there is also a reduction in the waste of harmful plastics. The fuel produced is most similar to diesel and can be used directly to start diesel engines. The biofuel generated has a pyrolysis Castrol oil content of 48.6%, a wax content of 40.7%, a pyroplin content of 10.1%, and a carbon black content of 0.6%, which is similar to plastic oil ^[43][47].

Brindhadevi et al. illustrated and explored the catalytic degradation of LDPE in a solid reactor using synthetic catalysts, which are expected to produce gasoline, hydrocarbon-rich liquid fuel, coke, and gas ^[47][51]. During the initial reaction, the TiO₂ catalyst generates the maximum yield of liquid fuel; as the reaction continues, this yield rapidly decreases. During cracking using the TiO₂/AlSBA-15 catalyst, the gasoline content rose from 45.6% to 85.4%, as did the liquid fuel efficiency (89.1%) and conversion (98.4%). The calorific value of the liquid fuel generated by the composite catalyst is 47.8 MJ/kg, which is higher than that of regular petroleum.