Promotion and Potential Analysis of Biogas Plants to Produce Compressed Biomethane Gas for Transportation in Thailand


 BackgroundThe implementation of activities agriculture resulted in a large amount of wastewater and organic waste. In the past, Thailand has been using these to produce biogas to replace fossil fuels in the country. At present, biogas production has a residual amount due to no use in farms/factories. So, it to be released into the atmosphere. The government has a policy of biogas by the upgrade to produced biomethane for fuel vehicles but it is still just a prototype system. Therefore, if the government has targeted of the development biomethane in commercial plants, it is necessary to analyze the financial feasibility to an incentive of investors and plan for energy effective support. Including, people can use gas at a reasonable price and create a comprehensive energy source in sustainable agriculture.ResultsThe research evaluates the commercial investment potential of compressed biomethane gas plants based on upgrading biogas by water scrubber technology. The results identified biogas plants must have a digester volume of 2,000 m3 or more to produce compressed biomethane gas. Locations of 10 plants with the potential to establish compressed biomethane gas plants in Thailand. The capacity of compressed biomethane gas plants at 3, 6, 12 and 24 tons/day with no subsidy, subsidy 20% and 30% from the government. The plant should have a capacity of 12 tons/day or more in on subsidy from the government that there will be a financial possibility. The government should be subsidy at 30% in the plants of capacity at 3 tons/day for small plants can operate their businesses, subsidy 20% in the plants of capacity at 6 tons/day. In the part of plants more 12 tons/day which the government should be added measures such as Measures for low-interest loans, tax relief measures, etc. In addition, 10 locations will be expected to reduce greenhouse gas emissions by about 78,333 tCO2e/year. Conclusion﻿This study can be used to support decision-making on commercial investment in clean technology to promote the use of resources in agriculture for efficient transportation and support energy-efficient plans to provide an alternative sustainable fuel source to reduce global warming.


Introduction
Thailand is located in the center of mainland Southeast Asia, covering approximately 513,120 km 2 with a total population of around 66.5 million [1]. Thailand's nal energy consumption in 2019 was 85,708 ktoe. The commercial energy consumption was shared 84.2% of the total nal energy consumption while the renewable energy was shared 9.9% and the traditional renewable energy was shared 5.9%. However, petroleum products consumption played the greatest proportion 49.10% of the total nal energy consumption, followed by electricity 20.25%, alternative and renewable energy 9.95%, coal/lignite products 8.30%, natural gas 6.50% and traditional renewable energy 5.90% respectively [2]. Agriculture is the main economic activity in the area, predominantly consisting of livestock farms such as cattle, pigs, laying hens, etc., and cassava and sugarcane elds, which are primary economic crops and support the industrial sector. However, wastewater and waste are involved in most agricultural activities. It is considered a potentially bene cial source of wastewater and wastewater utilization. As renewable energy, biogas is a sustainable alternative to fossil fuels, fuel oil, lique ed petroleum gas (LPG), electricity, etc. However, sometimes biogas needs to be emitted into the atmosphere. Therefore, the quality of biogas should be improved to produce biomethane for vehicles and is one option for maximizing the use of agricultural waste, reducing the use of fossil energy and the emission of greenhouse gases (methane) into the atmosphere.
Over the years, the number of NGV users in Thailand has increased because of the high oil price in the global market. Therefore, the government has implemented a policy to encourage cars, public vehicles, and trucks to switch to natural gas by xing the NGV gas price to make it cost-effective. According to the statistics as of March 2019, vehicles using NGV reached 380,931 cars increasing by 20% in the previous ve years [3].
The Thai government has recently introduced the concept of biogas puri cation to produce biomethane and as an option to replace petroleum in areas far away from a natural gas pipeline, such as the north, northeast (south area), and south (west area), since the supply and transportation of NGV to these areas is di cult and expensive. The supply of energy is limited in these areas with the transportation costs based on the distance from the mother station or natural gas pipeline [4]. Consequently, through the Energy Policy and Planning O ce, the government is promoting biomethane research to provide a solution to this problem by developing alternative energy using biogas puri cation for producing compressed biomethane gas (CBG). This CBG is the only renewable energy source with the potential to replace LPG and NGV, as well as being the only form of alternative energy in Thailand that can replace fuel oil for vehicles. Biomethane gas is biogas which undergoes quality upgrading by removing carbon dioxide (CO 2 ), hydrogen sul de (H 2 S), and moisture [5] using technologies such as water scrubbing, pressure swing adsorption, and membrane separation to meet the speci cations of vehicle fuel. However, to replace NGV for use in vehicles, biomethane gas must be stored at high pressure (up to 200 bar) [6] which is why it is called compressed biomethane gas (CBG). Biomethane gas and compressed biomethane gas have similar properties: they are lighter than air, experience no accumulation when leakage occurs, and only ammable at between 5-15% by volume at 650 º C. However, they have different methane content, with biomethane containing more than 80% methane by volume. Biomethane purity standard vary according to country. For example, the Netherlands requires at least 85%, Switzerland 96%, and Sweden 97% of CH 4 content in the injected biomethane [7]. The biomethane standard in Thailand is set according to the requirements of the Department of Energy Business, and must have the same properties as NGV, namely 83-89% methane by volume [8]. Therefore, it can be directly used as an alternative to NGV. Moreover, in Thailand, the calori c value of biomethane gas for use in cars must be between 37-42 MJ/Nm 3 [9].
Biogas plant in Thailand is scattered throughout the country. Thailand still lacks the integration and cooperation in making the most of the bene ts. This research is a considerable distance from the natural gas pipeline and considerable area has many biogas plants with the potential to establish a compressed biomethane gas station for local transportation. Therefore, this research focuses on the nancial, investment, subsidies from the government, and environmental bene ts (Reduction of greenhouse gas emissions). Investors can use the ndings to help in decision-making while the government sector can use the information for the effective planning and promotion of renewable energy technologies.

Methodology Of The Financial Investment And Greenhouse Gas Emission Reduction Assessment
Methodology of the nancial investment Background of the compressed biomethane gas promotion in Thailand The compressed biomethane gas project (CBG) is aimed at promoting alternative energy sources and supported by the Ministry of Energy to encourage the use of compressed biomethane gas to replace NGV under the Alternative Energy Development Plan (AEDP2015). The Ministry of Energy is investigating the concept of biogas puri cation to produce biomethane with similar properties to natural gas as an alternative to petroleum fuel in the areas far away from the natural gas pipeline. Biomethane gas is a clean fuel option for consumers and more entrepreneurs are supporting its production by investing in compressed biomethane gas stations in areas far away from the natural gas pipeline to help people gain better access to renewable energy sources. The AEDP2015 has a target to increase the proportion of energy usage by producing compressed biomethane gas from biogas to meet 5% of NGV demand with 4,800 tons per day, or about 2,000 ktoe by 2036 [10].
In accordance with AEDP2015, the Department of Alternative Energy Development and E ciency, Ministry of Energy aims to develop renewable energy through compressed methane by upgrading technologies to replace LPG and natural gas for vehicles (NGV), by supporting owners of plants who already have a biogas system and su cient biogas production capacity to produce compressed biomethane gas of no less than 3 tons/day. The level of support on offer for the construction and installation of biogas upgrading and compressed biomethane gas systems is no more than 15,000,000 baht per plant for large animal farm owners and the following seven potential industrial groups: cassava starch, food and beverages, palm oil, whiskey and beer, rubber, paper, and ethanol.
These plants must be currently under construction, already operating a biogas system producing excess biogas from electricity or heat energy or experiencing problems in connecting to the electrical grid. Although they may have a biogas production capacity of no less than 6,000 m 3 /day, plants must have the potential to produce no less than 3 tons/day of compressed biomethane gas. The total production of CBG from all project participants should be no less than 5 million kg/year. The government is supporting targeted areas more than 50 km from the natural gas pipeline. These include the northern, central, southern, and northeastern areas and those with problems connecting to the electrical grid (feeder line). The direct subsidy from the government is 20-30% of the investment cost for biogas upgrading and compressed biomethane gas systems, as shown in Table 1. Table 1. Investment support by the Thai government for compressed biomethane gas production [11].

Capacity CBG
Subsidy conditions 3,000-5,999 kg/day Less than or equal to 30% of the investment in biogas upgrading and compressed biomethane gas systems, but not exceeding 9 million baht per project.
6,000-11,999 kg/day Less than or equal to 25% of the investment in biogas upgrading and compressed biomethane gas systems, but not exceeding 12 million baht per project.
Equal to or greater than 12,000 kg/day Less than or equal to 20% of the investment in biogas upgrading and compressed biomethane gas systems, but not exceeding 15 million baht per project.
Thailand's Ministry of Energy announced the speci cations and quality of biomethane for vehicles in 2018 to build con dence and trust for investors and users. They determined that the pure methane gas content should not be less than 80% by volume, for use in vehicle fuel and can be used as direct fuel or mixed with natural gas.
The potential of biogas plants to produce biomethane gas  [13]. The Thai government began promoting the use of biogas in the rst swine farms, subsidizing approximately 33% of the total investment. Aggarangsi (2013) conducted a study on the development of biogas technology in Thailand's livestock farms, revealing that three main sectors in the country operate biogas systems: animal husbandry, the food industry, and community enterprises. These have the potential to produce more than 1 million m 3 /year of biogas, but only 36% of the total biogas can be used to replace fossil fuels [14].
Therefore, as previously mentioned, for maximize bene t, biogas should be used to produce biomethane gas to support sustainable energy in Thailand. Accordingly, the objective of this research is to identify areas with the potential to operate compressed biomethane gas stations to provide fuel for vehicles using the biogas system This research analyzes water scrubber in upgrading biogas technologies since it requires low capital and operating expenditure and does not require high-skilled operators (shown in Table 2). The costs of biomethane gas production can be divided into biogas cost, upgrading capital cost, upgrading operations and maintenance cost, capital cost of compressing equipment, compressing operations, and maintenance cost. 5 Energy Research and Development Institute at Chiang Mai University studied a local gas grid project submitted to the Energy Policy and Planning O ce. The result showed that 1 m 3 of biogas (at CH 4 55% by volume) converted to CBG production at 0.45 kg, including the cost of biogas pipeline transportation of approximately 702,777 baht/km was used to calculate the potential total cost of CBG production [10]. The researcher reviewed the appropriate biomethane cost pricing guidelines and determine the cost structure of biomethane production. The price structure is divided into two parts, separated according to the production process, namely the material cost (biogas purchase), the biogas pipeline cost and the biogas upgrading cost (biomethane produce process) and set the unit of product in the form of baht per kilogram. The scope of analysis is shown in g. 4.
From the cost-based pricing approach according to the study results "Biomethane Promotion Strategic Plan Project for Commercial Energy Use" prepared by Energy Research Institute, Chulalongkorn University. It is proposed to use a nancial model in which the project's suitable internal nancial rate of return (FIRR) by determining the purchase price of biomethane re ects the investment return not lower than the investment of other businesses that are at risk at the same level. The nancial model used to determine the purchase price of biomethane is a future cash ow valuation throughout the project life (this study analyzes the project life at 15 years.). The cash ow consisted of cash in ows and out ows. The cash ows must be high enough to motivate investors to invest in the development of biomethane system but it must not be too high that it is a burden to the government in the long term.
The spatial assessment of suitable areas for producing biomethane in Thailand. Researchers surveyed biogas plants that were distributed across the country by questionnaires with strati ed sampling. Then, grouped of biogas plans that near area analysis for transfer biogas by pipeline to the biomethane gas distribution station su ciently, determined the transportation distance is not more than 50 kilometers. Including, comparing the CBG production capacity of 3, 6, 12 and 24 tons/day in case of no government subsidy, subsidy 20% and 30% respectively.
Currently, Thailand has actively commercial CBG in one plant that replacing CBG with NGV. This plant has biogas purchase price of 2 THB/kg biogas and a purchase price of CBG at 15.68 THB/kg CBG . Including, the total of capital cost and operation/maintenance of CBG capacity 3, 6, 12 and 24 tons/day was 46.6, 67.9, 98.8 and 144.9 MTHB respectively. (shown details cost in g. 5) This research determines the equivalent heating value of CBG to NGV for vehicles at 43.46 MJ/kg (95% mol of methane). An investment feasibility analysis on the compressed biomethane gas stations was applied to identify the nancial indicators, namely: Net Present Value (NPV), Financial Internal Rate of Return (FIRR), Payback Period (PP), and cost per unit according to the conditions shown in Table 3.

Results
Potential biogas plant groups with the capacity to produce biomethane gas The network of pipelines in Thailand currently stretches 4,255 km from onshore to offshore [23]. There are pipelines through the central, western, and eastern areas, meaning that most of the transportation sector chooses to use natural gas as fuel, especially as the cost of natural gas is lower than biomethane gas. According to the Ministry of Energy's biomethane production promotion plan, areas far away from natural gas pipelines must bear the burden of higher fuel costs, while other parts of the country do not. Therefore, this research analyzes only these areas and the transportation of biogas from plants to compressed biomethane gas stations no more than 50 km away. Based on the research principles of PTT in 2017, the cost of transporting NGV for a distance of more than 50 km is not worth the investment. There is also the problem of using the highway as the main route for transporting biogas from the pipeline to the compressed biomethane gas plants. The location and distance from the pipeline of potential biogas production plants can be obtained from Google Maps and the Power BI program.
The group with CBG production capacity of 3 tons/day has three groups, namely group C, I and D with the remaining biogas from the utilization of 8,324,250 m 3 /year. The group with CBG capacity of 6 tons/day has two groups, namely group G and J with the remaining biogas from the utilization of 10,758,000 m 3 /year. The group with CBG production capacity of 12 tons/day has three groups, namely group A, B and E with the remaining biogas from the utilization of 28,795,800 m 3 /year. And, the group with CBG production capacity of 24 tons/day has two groups, namely group H and F with the remaining biogas from the utilization of 34,412,400 m 3 /year, as shown in Table 4.
From the results of this study, it can be seen that Thailand has a large amount of biogas remaining from its use (approximately 82,290,450 m 3 / year), but Thailand is still unable to utilize this biogas to its full potential. Thus, Thailand should therefore use this biogas as renewable energy as much as possible, to reduce emissions into the atmosphere which causes global warming. Financial investment feasibility analysis The nancial investment analysis was divided into 3 cases: 1) No subsidy from the government 2) subsidy 20% of the total investment and 3) subsidy 30% of the total investment. Including, divided into groups according to the capacity of CBG production at 3, 6, 12 and 24 tons/day in the condition of the distance biogas transporting by pipeline at 50 km. The study was as follows.
In no subsidy from the government, the nancial internal rate of return (FIRR) at CBG production capacity of 3, 6, 12, 24 tons/day was 7.97%, 10.12%, 25.13% and 28.44%, respectively. Production of 3 tons/day has the most payback period of 9.28 years with a unit cost of 14.65 baht/kg CBG , at a capacity of 24 tons/day has the shortest payback period was 3.58 years with a unit cost of 12.26 baht/kg CBG . Therefore, the project that has the possibility of investment was CBG plants have the production capacity of 12 tons/day or more because FIRR more than the market interest rate (12%). In subsidy from the government 20% of the total investment, the nancial internal rate of return (FIRR) at CBG production capacity of 3, 6, 12, 24 tons/day was 11.64%, 14.09%, 31.83% and 35.83% respectively. The production of 3 tons/day has the most payback period of 7.53 years with a unit cost of 14.02 baht/kg CBG , at a capacity of 24 tons/day has the shortest payback period was 2.68 years with a unit cost of 11.99 baht/kg CBG . Therefore, the project that has the possibility of investment was CBG plants have the production capacity of 6 tons/day or more because FIRR more than the market interest rate. In subsidy from the government 30% of the total investment, the nancial internal rate of return (FIRR) at CBG production capacity of 3, 6, 12, 24 tons/day was 14.08%, 16.76%, 36.52% and 41.04% respectively. Production of 3 tons/day has the most payback period of 6.28 years with a unit cost of 13.70 baht/kg CBG , at a capacity of 24 tons/day has the shortest payback period was 2.36 years with a unit cost of 11.86 baht/kg CBG . Therefore, all CBG plants have the possibility of investment. The results are shown in Table 5. So, in case no subsidy from the government at the maximum capacity at 24 tons/day will be lowed costs from the lowest production capacity (3 tons/day) of 16.31%, subsidy 20%, at the maximum capacity at 24 tons/day will be lowed costs from the lowest production capacity (3 tons/day) of 14.48%, subsidy 30% at the maximum capacity at 24 tons/day will be lowed costs from the lowest production capacity (3 tons/day) of 13.43%. it can be concluded that the higher the amount of CBG will have the potential for a greater return on investment, and the increased production capacity of the CBG plants, cost price of CBG per unit will be lower. (shown in Fig. 6 and Fig. 7) However, biomethane has the potential to be cost-effective in terms of performance bene ts on the customers and entrepreneurs can supply fuel to operate their businesses sustainably. In particular, large scale production of more than 12 tons/day which the located near a potential source of biogas plants. It makes more competitive in the market. But, if it is a small CBG plant less than 12 tons/day, it will not be cost-effective because of the cost of producing CBG still higher than other fuels.

Reducing greenhouse gas emissions
The results show that three groups have the capacity to produce CBG at the rate of 3 tons/day can be greenhouse tons/year can be reduction in greenhouse gas emissions about 78,333 tCO 2 e/year, as shown in Fig. 8.
However, if the government can facilitate the construction of all CBG plants, the consequent reduction in greenhouse gas (methane) emissions into the atmosphere will mitigate the impact of environmental pollution. Furthermore, it will support the policy of the United Nations Framework Convention on Climate Change (UNFCCC) to achieve operational cooperation and common global goals. The aim of the UNFCCC is to strengthen the global response to the threat of climate change by holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels [24].

Conclusions
The integration of biogas plants is helping to strengthen of energy and agriculture sector. Promoting the adoption of clean technology in the production of renewable energy makes areas far away from the natural gas pipeline to be able to use clean energy and local resources e ciently. The results showed that Thailand has 10 potential areas for establishing CBG plants. A Plant with a large quantity of CBG capacity per day is a good nancial return on investment. On the other hand, plants with a low quantity of CBG capacity per day are not nancially viable. This is because larger plants have lower unit costs. The government should help nance these groups by subsidy at least 20% of the total investment. Including, increase tax measures or lower loan interest rates for large-capacity plants with incentives to continue operations in the long term. CBG has advantages in transportation compared to other fuels, because transportation is near to biogas plants within a distance of less than 50 km. In the future, the promotion of the use of CBG in the transport sector will be very cost effective when the price of natural gas tends to rise. While the cost of CBG production still the same. However, for CBG plants in Thailand to be commercially viable, the government would still have to provide subsidies to stimulate investment in the project and build con dence to encourage more vehicle owners to consider this energy choice. Furthermore, if the government decides to speed up the plan to promote CBG stations then it should have a proper plan to support all biogas plants, thus enabling them to increase or maximize production. The government also needs to manage its subsidy support and investment promotion policy at the same time. For this reason, helping to make CBG widely used all over the country, helping to reduce costs on importing energy from abroad and reduces environmental impact.

Recommendations
From the above study, can summarize the model of promotion of the establishment of compressed biomethane gas distribution station in Thailand by dividing the promotion into 3 phases as follows: The rst phase (2020 to 2022) is the large investors or with nancial readiness and is a technology-respected person. They have the con dence to invest. Thus, the way of promoting in this group should be promoted water scrubbing technology as it is the lowest cost technology and promote the establishment of stations in the area with potential rst to be a model for other entrepreneurs. But, this groups no have subsidy from the government that they have the potential of nancial investment, the government should add other policies to support such as investment support measures, tax measures and measures for low interest loans, etc. The second phase (2023 to 2030) is the start of the growth of technology. Most of the entrepreneurs began to see examples from the rst phase of entrepreneurs.
They were imitated and gained market share quickly. Therefore, if the government wants biomethane to be used as renewable energy for vehicles and cover remote areas. The government should be subsidizing to all CBG plants. Which subsidy 20% for CBG plants have the capacity production lower than 6 tons/day and 30% for CBG plants have the capacity production more than 12 tons/day. The third Phase (2031 onwards) is the beginning of the market saturation. Most investors are widely accepted in technology and there are many imitations to create stations. The market share may not be even half that the risk not worth the investment. In this period, if the government wants to support the continuous construction of biomethane gas stations to seriously replace fossil fuels, the government needs a relatively high subsidy for the purchase price. In addition, the government should add other policies to support same as the rst phase such as investment support measures, tax measures and measures for low interest loans, etc. (shown in Fig. 9) However, in the case of the private sector to operate a government project. Private investors invest when the nancial rate of return of a private-invested project is higher than the market interest rate. The government should be set the difference of both rates at the appropriate level. In addition, the government should mainly consider the interests of the people who use the service. And then, consider the private sector will return to government organizations in the secondary order. This is to ensure the service fee is fair to users and service providers.
In addition, the government should make a signi cant contribution to the environment because not only is biomethane a renewable energy source, it also helps to reduce greenhouse gas emissions. Moreover, development of these biomethane plants would support the policy of the UNFCCC, reinforcing Thailand's commitment to reducing greenhouse gases by 20-25% by 2030 [25]. This policy aims to drastically reduce fossil fuel consumption while increasing the use of clean energy through environmentally friendly processes, thereby supporting the common goal of many countries around to world, namely to reduce global warming.