Nowadays, climate change is giving a more serious impact to the world. Climate change is caused by greenhouse gases (GHG) that trap heat in the atmosphere, such as carbon dioxide (CO2) and nitrous oxide (NOx). CO2 dominated the global GHG emission by 81% in 2018 [1]. In Indonesia, the transportation sector became the second highest CO2 emitter in 2017 by 28% [1]. It is because Indonesian transportation still heavily relies on crude oil-derived fuels which emit CO2, during combustion. The GHG emission from transportation in Indonesia is expected to increase from 143 MtCO2 in 2015 to 218 MtCO2 in 2030.
Meanwhile, the national crude oil production is declining and has been lower than the consumption level since 2004 due to the natural decline [2]. However, at the same time, the fuel demand must be met. Therefore, there must be an effort to find and commercialize a more sustainable substitute product of crude oil-derived fuel in order to mitigate climate change by reducing greenhouse gas emission and carbon footprint, and to reduce the national demand for crude oil.
Biodiesel can be considered as one promising alternative energy resource for petroleum products due to environmental issues and the decreasing fossil fuel resources [3]. With very minimal modifications or even without any modification of the engines, biodiesel can be used directly. Biodiesel itself is commonly produced from transesterification of high-fat plants, such as palm and soya. Despite that palm oil contributes a maximum share of 35% compared to others, the demand has driven palm oil plantations to deforestations and threatened biodiversity [3]. Therefore, more sustainable feedstock is required to substitute the use of palm oil.
Used cooking oil (UCO) has the potential to be considered as a more sustainable resource for biodiesel production. The fact says many countries, such as the United States and European Union promote industry development and the use of biodiesel derived from UCO [3]. The transesterification technology has been commercially used for biodiesel production. However, the UCO still consists of oxygen that lowers its efficiency of heating value. Researchers have found hydrotreatment method as a new way to convert UCO to a better quality of biodiesel, usually known as Hydrotreated Used Cooking Oil (HUCO) [4]. Therefore, we propose commercializing HUCO as a more sustainable product to substitute crude oil diesel.
Animal fats. Cooking oil consumption in Indonesia reaches 6,2 mT/year and there is no effort yet to collect and treat UCO for other uses [12]. Mostly, UCO is being re-used as new cooking oil, which causes negative impacts on public health, or disposed into drainage and contributes to environmental problems. Easy way collecting UCO usually is obtained from public areas such as restaurants, hospitals, cafeterias, and the food industry [5].
With a more integrated system which covers households all around the country, 1.68 billion litres of UCO can be collected and utilized as mixture component diesel fuel [5]. Besides to reduce the negative impacts on health and environment, utilizing UCO brings profit and positive impacts on the energy sector. Nowadays, most countries use transesterification palm oil as biodiesel, which also still brings slight negative impact, yet scientists have found technology to convert UCO to better quality biodiesel using hydroreatment. This method meets the circular economy of palm oil.
The role of energy in the economy of a country can be from two sides, which are demand and supply. In the terms of demand, energy is a directly consumed product. Meanwhile, in the terms of supply, energy is a key factor in the production process. This makes energy as a driving force for a country’s economy [7]. Along with the increasing number of population and economy, Indonesia’s energy needs increase from year to year. The achievement of energy supply in 2019 reached 219.08 million tonnes oil equivalent (MTOE), increased from 2018 which was 205.25 MTOE. The energy mix consists of renewable energy, petroleum, coal, and natural gas. From the same data, the use of petroleum has decreased from 79 MTOE in 2018 to 73.56 MTOE and for renewable energy has increased from 17.54 MTOE to 20 MTOE [8].
These numbers show how committed Indonesia in reducing the impact of depleting fossil fuels as well as the environmental impacts it causes. Not only does by Indonesia, the limitation of using fossil fuel energy and replacing it with renewable energy, usually known as the utilization of renewable energy, has become a joint program from various countries in the world. In 2015, the 21st Conference of Parties was held in Paris and resulted in an agreement to stop global warming by limiting Greenhouse Gas (GHG) emissions. Based on National Energy Board’s data, Indonesia is targeting to increase energy supply by 400 MTOE by 2025 with at least 23% of renewable energy, which are from geothermal, hydro, wind, biomass, and other sources, also will be allocated to generate electricity by 75% and 25% for engine fuel. National Energy Plan (RUEN) data shows the rise of utilization of renewable energy as engine fuel from 13.6 MTOE in 2019 to 15.2 MTOE in 2020 [8]. This indicates the trend of using renewable energy in society is increasing and in line with the commitment to reduce negative impacts on the
The common biofuel is biodiesel fatty acid methyl esters, however, it still has acidic number and low heat value due to the presence of oxygen which reduces the efficacy [9]. Recently, research has found similar properties of UCO to diesel fuel and it has been considered as the sustainable material for biodiesel production, only it needs to be treated due to high viscosity and oxygen contained [10]. Improved refining and treatment are needed to enhance the quality of UCO-based biodiesel.
Catalytic hydrotreatment can be the answer to this problem. Although hydrotreatment is popular in petroleum refineries to remove S, N, and metals, only lately it has expanded in the area of biodiesel production. Hydrotreatment is more advantageous over transesterification because of its lower processing cost, compatibility with the infrastructure, NOx emission reduction, and feedstock flexibility. Hyrdotreatment consists of two main steps, the hydrotreating of UCO and isomerization. The hydrotreating occurs in the form of deoxygenation, decarbonylation, decarboxylation, improved the cetane number by reducing oxygen contained in UCO. But the fuel produced still has high cold flow properties which are not suitable for the engine. Therefore, isomerization is needed which addresses an improved fuel with sufficient low cold properties [10].
The catalyst used is Ni/Co-Mo-based supported with Al2O3, usually is used in petroleum refineries to maximize the desulphurization and denitrogenation efficacy while in vegetable oil, or in this case is UCO, can reduce the heteroatom oxygen. This usage of this catalyst in hydrotreating along with H2 offers high yield, around 90% conversion [11].
For industrial production, the UCO collected after filtration is fed in the reactor along with H2 at 1:500 ratio. The catalytic hydrotreatment occurs at 340oC and produces gas and liquid products. The gas product contains the excess H2, CO and CO2 (by product from decarbonylation and decarboxylation), and light hydrocarbons. After the cleaning process, the gas product is recycled as the main resource of H2. The liquid product contains the diesel fuel molecules and water. Both gas and liquid products are separated resulting in diesel fuel only which is mainly paraffin and Iso-paraffin. The liquid products still need to be isomerized which enables to convert the normal paraffin to iso- and cyclo- paraffin, the more stable diesel fuel [10], [11].
We propose H30 which is a blend of 30% HUCO and 70% fossil diesel in a litre of fuel since it is more recommended than the use of neat HUCO (H100) [5]. Firstly, the viscosity of H100 is high and its volumetric calorific value is lower than fossil diesel due to its lower density. Secondly, its high cetane index requires engine adjustments. Lastly, it is impossible to completely substitute fossil diesel since the current national fuel consumption is higher than the national UCO production.
H30 has similar properties to fossil diesel and D30 and even better cold properties and higher cetane index than B30. Also, due to its higher heating value, H30 has shorter ignition delays, thus it can provide more time to complete the fuel combustion process. In addition, all H30 fuel properties already meet the Indonesian government’s regulation of diesel fuel standards according to Kepdirjen Migas Nomor 28.K/10/DJM.T/2016.
H30, as a new biofuel technology, needs a comprehensive environmental impacts analysis during its life cycle, called as Well-to-Wheels (WTW) analysis. The total WTW GHG emissions of fossil diesel, B30, D30, and H30 are 88.6 g CO2eq/MJ, 80.7 g CO2eq/MJ, 76.6 g CO2eq/MJ, and 64.5 g CO2eq/MJ, respectively [6]. Therefore, H30 yields 27% saving of WTW GHG emission in respect to fossil diesel which is higher than B30 and D30 with 9% and 14% savings, respectively.
Increasing the UCO collection for H30 production would also have health benefits by preventing UCO reuse in food. Repeated use of cooking oil increases the level of 4-hydro-2-trans-nonenal in the oil which is a toxic substance linked to stroke, Alzheimer’s, Parkinson’s, and Huntington’s diseases.
The best pricing scenario for H100 product is to reach break-even point after 10 years, thus the H100 fuel price would be 0.743 USD/L or 10,400 IDR/L assuming that 1 USD equals to IDR 14,000 [7]. Taking that Indonesia’s non-subsidized diesel fuel price is 9,400 IDR/L, thus the approximated price for non-subsidized H30 would be 9,700 IDR/L. In order to comply the Public Service Obligation that states the subsidized diesel fuel price in Indonesia must be 5,150 IDR/L, the government must provide a subsidy of 4,550 IDR/L of H30 which is 300 IDR/L higher than the subsidy for conventional diesel fuel. However, the government could save the crude oil import deficit. Given that the possibly collected UCO in Indonesia is 3 billion L/year with HUCO blending percentage is 30% and assuming that the hydrotreatment yield is 90%, the H30 production per year is 810 million L/year, equivalent with 5.09 million barrels oil per year. Assuming that the oil price is 50 USD/barrel, hence, the government can save up to 254.7 million USD each year from crude oil imports.
To support the energy resilience, Indonesia could commercialize H30 which is a blend of 30% HUCO and 70% fossil diesel as an alternative biofuel with competitive quality compared to conventional diesel. This program could contribute in reducing GHG emissions while also saving money from importing crude oil. Indonesia produces a large quantity of UCO, which is mostly wasted or reused in food with negative health impacts. However, the effective way to collect UCO to be produced as HUCO still have to be worked out. Therefore, an integrated effort from every stake-holders is needed to put H30 into the commercialization stage.
2021-2-28-1614489362