Sustainable energy transition in Bangladesh: Challenges and pathways for the future

The industrial development of a country plays a vital role in its overall progress and is closely tied to its capacity of electricity generation. However, the scarcity of natural resources and increasing costs of fuel in global markets pose significant challenges for developing countries like Bangladesh in managing the rising expenses of electricity generation. Consequently, the government of Bangladesh is exploring alternative energy resources such as solar, wind, hydroelectricity, biomass, and biogas to supplement fossil fuels and optimize electricity generation cost. This paper aims to provide a comprehensive overview of the current status of natural resources, including gas, coal, and oil, which are conventionally used for electricity generation in Bangladesh. It highlights concerns about dwindling resource availability and their impact on the country's energy landscape. Through numerical analysis, it demonstrates the detrimental effects of relying heavily on gas‐based power plants, leading to electricity supply instability. To address the ongoing energy crisis, the paper proposes the adoption of renewable energy sources as a viable solution. Additionally, it also acknowledges the challenges associated with implementing large‐scale renewable projects in distinct areas of the country, such as limited infrastructure, technical constraints, and the need for significant investment. Overcoming these barriers is crucial for achieving widespread utilization of renewable resources. This paper concludes by offering recommendations to overcome these challenges and maximize the contributions of renewable energy in meeting future energy demands. The suggestions include developing robust infrastructure, implementing policy reforms to attract investment, emphasizing research and development, and promoting community engagement in renewable energy initiatives. It also highlights the potential of renewable energy resources in shaping a more secure and sustainable energy future for Bangladesh, emphasizing the importance of electricity generation for socio‐economic development.


INTRODUCTION
A developing country like Bangladesh has significantly increased its electricity generation capacity over the last decades.Most of this generated electricity supports the growing export-oriented industry sector, which is the foremost component of ensuring sustainable economic development.But, the country has been facing numerous challenges in ramping up the electricity supply due to its acute shortage of fossil fuels.As per the annual energy reports from the past couple of years, depicted in Figure 1, more than 85% of the total electricity generation is continuously sourced from conventional fuels, with natural gas dominating the contribution with over 50% each year. 1,2It has also supported domestic and industrial sectors over the last few decades.But, extensive use of these fuels, especially natural gas, raises concerns about their available reserves for future production.Moreover, some recent survey research reports [1][2][3][4] and articles [5][6][7] have already anticipated that these fuels' existing reserves will run out within the following decades.Despite having a reasonable coal reserve, multiple issues like high extraction costs, location in densely populated regions and so forth, force us to purchase a significant amount of coal to generate electricity. 8Moreover, there is no significant oil reserve that demand fulfills by only importing. 9The rising price in the world energy market due to war scenarios and natural calamities eschews the import of these fuels to maintain stable foreign reserves. 10Therefore, finding an alternative source of electricity generation is a national goal for further development.It inspires 2400 MW future generation from costly nuclear fuel, forecasted to be operational within the next few years.This project associates massive initial expenditure, challenges in adapting advanced technology, and concerns about energy market regulatory risks.As a consequence, the government is prioritizing the establishment of renewable energy plants over traditional fossil fuel plants to meet the country's significant electricity demand, driven by the favorable geographical location of Bangladesh. 11However, in recent years, these sources, primarily solar power, have accounted for only 0.38% of the total electricity generation. 4This percentage is insufficient considering the country's electricity demand, especially due to the ongoing decline in fossil fuel reserves.As a result, the government continuously offers multiple incentives to public and private developers for installing large-scale renewable projects to enhance the contribution from these sources.But developers faced numerous challenges in large-scale implementations, primarily due to government organizations' lack of support and experience in adapting new technology involving these plant establishments.This paper explores the current state of the country's electricity generation scenario and highlights the impact of the gas shortage on future generations.It illustrates the existing fossil fuel reserves, such as natural gas, coal, and oil, whose rapidly declining nature raises more concern about the sustainable future.It portrays the country's existing renewable energy penetration framework and future installment plans focusing on solar, wind, hydro, and biogas systems.Additionally, it addresses the potential challenges in implementing large-scale renewable projects in underdeveloped localities through public and private developer organizations.It also proposes possible action plans encouraging developers to achieve the millennium development goals by raising renewable penetrations.

PRESENT ENERGY SCENARIOS
As of 2041, Bangladesh strives to be a developed country, primarily focused on the government's multiple master plans illustrating a roadmap for future power sector development.To meet its electricity needs, it is predominantly reliant on fossil fuels.But rapid degradation of these leaves the country to find an alternative source to meet the current energy crisis.This section addresses the current electricity generation status along with the existing fossil fuels inventory.

Status of electricity
The dependency on electrical energy in every sector is continuously increasing, and it has become a fundamental right to access electricity for the individual in today's modern arena.The government has already taken multiple steps to bring the mass people and areas under the shadow of electrification. 12They also encourage the development of economic zones, mills, and industry to enhance the overall GDP growth ($416 billion in 2022) and step toward the developed country list.These recent establishments significantly increase the total electrical energy consumption and demand rate.As a result, energy consumption during the year of 2021-2022 reached a total of 85,607 GWh, exhibiting a substantial increase of approximately 5184 GWh compared to the preceding year. 1 This upward consumption trend is projected to drive an annual demand growth of around 7%, as shown in Figure 2. 2 It is also forecast that Bangladesh will need 57,000 MW of F I G U R E 1 Annual electricity generation breakdown by fuel sources. 1,2I G U R E 2 Electricity demand up to the year 2040. 1

F I G U R E 3
Installed plant capacity based on fuel types. 1,2,13ectricity generation to overcome its electricity demand in 2040. 1 This increasing demand is continuously forcing us to raise electricity generation capacity.As of June 2023, Bangladesh has installed a plant capacity of 26,007 MW, utilizing various fuels such as natural gas, coal, furnace oil, and diesel, as depicted in Figure 3. 13 This indicates a predominance of electricity generation from diversified fossil fuels in the last few years.However, there is now a growing contribution from renewable energy sources.But, the country's average daily total generation hovers around 12,500 MW, with the highest recorded generation reaching 14,800 MW. Te demand for electricity escalates significantly during the summer due to extreme weather conditions.This data reveals that despite having a substantial installed capacity, the country is currently generating just above 50% of its total capacity.The primary reason behind this discrepancy is the inadequate supply of fossil fuels, particularly natural gas, coal, and oil, to multiple power plants.As a consequence, these plants are compelled to operate below their rated capacity.In order to bridge this gap and meet the escalating electricity demand, it is imperative to address the issue of insufficient fuel supply.Furthermore, this issue poses a substantial financial burden on the government as it incurs additional capacity charges for privately-owned power plants that face insufficient fuel supply.This is a matter of utmost significance, especially considering that the private sector holds a significant stake of around 45% in the country's total plant capacity. 2 Experts have strongly recommended the renegotiation of capacity payments with power plant owners to address the challenge of declining foreign reserves.By proactively addressing fuel supply constraints in the electricity sector through constructive dialogues and effective measures, financial strain can be alleviated, power generation infrastructure utilization can be optimized, and sustainable solutions can be found.
Based on the empirical data presented in Figure 3, it is evident that gas holds a significant share in the energy generation landscape of the country.This includes the contribution of captive power plants and multiple gas-based facilities, which collectively account for a substantial 44% of the daily electricity generation. 13However, this heavy reliance on gas resources presents several challenges.Notably, in the previous year, gas-based electricity generation consumed approximately 46% of the total gas extracted from diverse gas fields, as reported in the annual inventory. 2This highlights the significant consumption of gas resources by the power sector, indicating a heavy dependence on gas for electricity generation.The high utilization of gas underscores the importance of diversifying the energy mix and reducing dependency on gas by promoting the integration of renewable energy sources.However, the increasing demand for electricity poses a formidable task as it requires an augmentation of gas extraction to sustain the full-scale operation of multiple power plants.Alarming forecasts also indicate that the projected gas demands for future electricity generation, as well as for industrial and domestic sectors, as outlined in Table 1, are poised to surpass the potential supply by the year 2030.These circumstances raise concerns about the long-term sustainability of a gas-dominated electricity generation paradigm.To ensure energy security and mitigate the risks associated with over-reliance on gas, it is imperative to diversify the energy mix and explore alternative energy sources.Prioritizing the implementation of solar, wind, and hydroelectric power projects can enhance the resilience of the energy sector while alleviating the strain on gas resources.Furthermore, it is crucial to enhance energy efficiency measures, promote conservation practices, and foster innovative solutions to meet the surging electricity demand while mitigating the impact on gas supply.Embracing a comprehensive and multidimensional approach will enable the country to navigate the challenges posed by the diminishing gas reserves, pave the way for sustainable energy development, and ensure a reliable and secure electricity supply for future generations.

Status of natural gas
Natural gas has been a driving force in Bangladesh's electrical generation, as seen in Figure 4, fueling the nation's rapid economic growth since its independence. 1This valuable energy resource has not only met the country's electricity needs but also stimulated various sectors, contributing to overall development.The quest for oil and gas in this region began in the 19th century, supported by limited geological mapping data. 14The Indian Petroleum Prospecting Company made the first significant attempt to find oil and gas in Sitakunda in 1908, 18 years after the initial oil discovery in Digboi, Assam. 15Subsequently, the Burmah Oil Company drilled two shallow wells in Patharia between 1923 and 1931, although no discoveries were made.In total, six exploratory wells were drilled, with the deepest reaching 1047 m.However, further activities were disrupted by the onset of the Second World War.The promulgation of the Petroleum Act in 1948 attracted international oil companies, including STANVAC, PPL, Burmah Oil Company, and PSOC, to further explore the country's resources.Despite several unsuccessful drilling attempts by STANVAC and PSOC, PPL successfully discovered gas in Haripur and Chattak during the 1950s.PSOC achieved significant success by discovering five gas fields, including the first offshore well, Cox's Bazar-1. 15In 1961, the establishment of the Oil and Gas Development Corporation laid the groundwork for further oil and gas exploration in Bangladesh.After gaining independence in 1971, exploration activities by both national and international companies gained momentum.Petrobangla, fully known as the Bangladesh Oil, Gas, and Mineral Corporation, played a key role in continuing exploration efforts.The enactment of the Bangladesh Petroleum Trend of energy generation from gas resources. 1,2t in 1974 facilitated international participation through production sharing contracts (PSCs).Companies such as Ashland, ARCO, BODC (Japex), Union Oil, Canadian Superior Oil, and Ina Naftaplin took up PSCs and conducted surveys along with drilling operations in the offshore area.Among them, Union Oil Company discovered the Kutubdia gas field in 1977. 15A significant milestone occurred on August 9, 1975, when the government purchased five major gas fields from Shell Petroleum Company Limited, strengthening the country's energy security.Subsequently, Petrobangla intensified exploration activities, leading to the discovery of the first commercial oil pool, Sylhet no. 7, in December 1986.The establishment of BAPEX as the Bangladesh petroleum exploration and production company in 1989 further advanced exploration efforts, resulting in the discovery of gas in additional locations through exploratory drilling.The formulation of the National Energy Policy in 1996 and the adoption of PSCs marked a new phase of exploration, with several gas fields such as Moulvibazar, Sangu (offshore), Bibiyana, and Jalalabad being discovered and developed.Till now, Bangladesh has made significant progress in gas production and exploration, with 20 out of 28 discovered gas fields already in production as of December 2021. 3This led to a peak gas production per day surpassing 2700 MMCFD in December 2016, indicating the growing capacity of the gas sector.However, despite the increase in production, the rising demand for gas has created a widening gap between supply and demand, illustrated in Table 1.To address this challenge, Bangladesh began importing liquefied natural gas (LNG) in August 2018.The introduction of LNG imports has helped to bridge the supply-demand gap by supplementing domestic gas production.Additionally, massive exploration programs are being implemented in both onshore and offshore areas.These programs aim to discover new gas fields and increase the overall production capacity of the country.Bangladesh's current natural gas output, including re-gasified LNG, stands at around 2.95 billion cubic feet (BCF), according to Petrobangla. 15The majority of gas extraction, about 90%, occurs in the eastern parts of the country, as depicted in Figure 5.Over the years, approximately 18 trillion cubic feet (TCF) of gas have been extracted from these fields. 16owever, recent reports indicate a decline in gas production, particularly at the Kailash Tila gas field in Sylhet, which has experienced a drop in production capacity from an average of 69 MMCFD to 29 MMCFD between 2020 and 2022. 5s a result, extraction from five wells in this field has been suspended due to insufficient gas reserves.On the other hand, Titas gas field has emerged as the top gas producer in the country, with recorded gas production of around 5186 BCF since its discovery.It is estimated to have an anticipated reserve of 2696 BCF. 17 However, most of the gas fields in Bangladesh are now facing rapid depletion of reserves, as shown in Table 2, raising concerns for the country's developing economy.Currently, only 20 out of the listed gas fields are currently fully operational, contributing to the scarcity of gas reserves.These operational fields are estimated to hold nearly 11 TCF of gas.However, recent surveys depicted in Figure 6, indicate a decline in gas production by 286.4 MMCFD over the past 2 years. 18This downward trend is expected to continue, potentially leaving Bangladesh completely gas-free by 2030-2041.To address the decline in gas production, the government is actively searching for new gas fields in various locations within Bangladesh.Promising areas, such as Patia, Sitapahar, and Kasalong in the Chittagong Hill Tracts, have already shown potential with the discovery of anticlinal structures.However, exploration and drilling activities in these areas are still at an early stage due to logistical challenges posed by the mountainous terrain.Additionally, the government can consider re-excavating dry and discontinued gas fields.This approach can help maximize gas extraction by utilizing existing resources.It would involve assessing the feasibility of reactivating wells, implementing modern extraction techniques, and leveraging advanced technology for F I G U R E 5 Geographical location of existing gas and coal fields in Bangladesh.

TA B L E 2
Declination of gas extraction and reserve from year 2016 to 2022. 5,15,20

F I G U R E 6
Shifting landscape of gas production: 2016-2022. 4,20hanced recovery.Furthermore, offshore gas exploration presents significant opportunities for Bangladesh.However, the country has lagged behind neighboring countries like Myanmar and India, in this area due to a shortage of advanced machinery.Out of the 26 shallow and deep exploration blocks listed offshore, only four have been explored thus far. 19To unlock the potential of offshore gas reserves, the government needs to invest in advanced machinery and technologies capable of exploration and extraction in offshore environments.However, the declining gas production in Bangladesh highlights the importance of diversification and investment in alternative energy sources.To reduce dependence on depleting gas reserves, the government should prioritize renewable energy projects, such as solar and wind power.This shift toward renewable energy sources will not only enhance energy security but also contribute to sustainable and environmentally friendly development.In addition to promote renewable energy, energy conservation and efficiency, measures should be implemented at all levels.This includes adopting energy-efficient technologies, improving infrastructure for energy transmission and distribution, and raising awareness among the population about responsible energy consumption.To ensure a secure and sustainable energy future, Bangladesh needs to develop a comprehensive long-term energy strategy.This strategy should involve extensive planning, research and development, and international collaborations to harness the potential of renewable energy sources effectively.By embracing sustainable and environmentally friendly solutions, Bangladesh can overcome the challenges posed by declining gas reserves and ensure a reliable and sustainable energy supply for its citizens.

Status of coal reserves
Coal was considered the world's primary commercial energy source until the end of the 19th century.But, the development of petroleum resources has significantly reduced its contribution to the existing global energy mix.Yet, it remains a dominant fuel globally, including in Bangladesh.The country's geological survey has discovered five Gondwana coalfields in distinct locations, such as Jamalganj, Barapukuria, Khalashpir, Dighipara, and Phulbari, depicted in Figure 5.However, several geologists have been predicting the possibility of large coal deposits beneath the alluvial plain of North Bengal for more than 170 years.The geologists' hopes were vindicated when searching for oil in 1959, resulting in the drilling of a hole in Kuchma X-1 in Bogra district by the standard vacuum oil company, where Gondwana coal encountered a depth of 2381 m from the surface. 14Consequently, in 1961 under a mineral survey project, the survey authority conducted exhaustive geological, geophysical, and drilling operations in Bogra and Rajshahi districts and found about 1050 million tons of coal resources in Jamalganj.Though country's largest coalfield, Barapukuriua of Dinajpur district, was discovered in 1985, where coal layers were encountered at a shallow depth of about 119-506 m. 21In 1989 another survey found coalfield at Khalashpir in the Rangpur district experiencing coal layers depths of about 257-483 m.An Australian coal mining company discovered another coalfield named Phulbari in 1997, having coal layers depths of about 150-240 m. 22 These coalfields accumulated proved and indicated reserve is around 1242.22 million tonnes (Mt) by October 2022. 23The field-wise coal reserve in Bangladesh is summarized in Table 3.Despite having an immense reserve, the country still has to purchase substantial coal from other countries such as Indonesia, South Africa, and India. 24It is primarily due to the requirement for advanced machinery and expertise to extract and process coal from most domestic reserves.In addition, the existing coal mines and the adjacent plant polluted the local rivers and other waterways, precipitated an underground water shortage, and damaged the health of their workers, residents, and the countryside, raising concerns about agricultural land availability. 25It forced the government to purchase the highest quality coal to establish 29 new coal-based plants in the following two decades, boosting the electricity contribution by 35%. 24The domestically produced and imported coal scenarios of the last 5 years are listed in Table 4. Currently, 2.55% of electricity is produced  F I G U R E 8 Projection of coal supply in Bangladesh. 27om domestic coal, primarily through the 524 MW plant at Barapukuria. 23But imported graded coal encourages the government and multiple private ventures to finance large-scale plants such as Payra at Potuakhali (1244 MW), Matarbari at Cox's Bazar (1200 MW), and Rampal at Bagerhat (1320 MW).As a result, the net energy generation from the coal resources is around 5342 GWh (6.24% of the total) in the year 2021-2022, 1 which is 7% more than the last year, as seen in Figure 7.But the higher cost of coal on international markets raises the energy cost from these plants to nearly double compared to previous estimates.It forces the government to reassess existing coal-fired plants to improve its energy supply and curb costs.However, Bangladesh has been facing wide-scale power cuts over the last few months, primarily due to acute gas shortages.It leads the country to lean on more coal than natural gas in power generation.It is expected to add 4365 MW of coal-fired capacity in the coming years' causing the share of coal in electricity to double. 26This massive generation will mainly come from the newly planned plants using imported coal to generate electricity, resulting in 27,000 tonnes of coal daily requirement.It will also cause a massive ramp-up in coal supply from import than domestic in future years, as projected in Figure 8.

Status of oil resource
Bangladesh has depended on importing crude oil and refined petroleum products since its independence to provide security to the energy supply.It mostly imports from Arab nations like Saudi Arabia and United Arab Emirates. 1 However, the country's only commercial accumulation of oil was discovered in Haripur, Sylhet, in 1986 while drilling an appraisal cum production well in a gas field. 14It produced about 0.56 million barrels of oil due to its tiny size compared to international requirements.It was forced to suspend production due to the declined oil flow and excessive water output in those fields in 1994.Later, in 2012, Bangladesh Petroleum Exploration Company found another financially feasible oil resource in the northeastern Sylhet region, estimated to contain approximately 153 million barrels of oil in two existing gas fields. 28Locally, these domestic sources generate approximately 0.52 million metric tons of gas condensate each year, split into liquid fuels such as petrol, diesel, and kerosene.This production can only meet 7.26% of the total 6.3 million metric ton demand of liquid fuel in the year 2020-2021. 1It forces the government to import a significant amount of crude oil (1.31 million metric tons) and refined petroleum products (4.3 million metric tons) yearly.The accumulated amount contributes primarily to transportation (63%), electricity (10%), agronomy (15%), industry (7%), households (2%), and others (3%). 1 But the ongoing power crisis in Bangladesh prompted by a gas shortage dismantled the authority to revise the multiple oil-fired power plants' lease renewals. 29Moreover, despite skyrocketing fuel oil prices amid the war in Ukraine, the administration has planned to increase fuel oil imports by about 15 million tonnes in 2023. 30It will mainly feed fuel oil-based power plants to tackle chronic power outages already hitting life and livelihood hard.Though authority already imported 44 million tonnes of fuel oils in 2021.As a result, according to the Bangladesh Bank, the country spent $8.9 billion on importing petroleum products in the financial year (FY) 2021-2022, about 67.71% more than $5.3 billion worth of imports in FY 2020-2021. 30Economists also warn that it will further pressure the country's foreign exchange reserves. 31

RENEWABLE ENERGY RESOURCES
The rapid decline of natural gas forces us to find an alternative and effective source for electricity generation, which needs to cover more than 50% of the total demand in the near future.However, achieving such a significant generation from other fossil fuels like coal or oil is challenging due to their high cost, limited availability, and environmental concerns.Moreover, the government's reliance on importing one tenth of the total electricity demand from India to address the increasing demand carries long-term disadvantages, including the rapid depletion of foreign reserves. 2While electricity can be produced from nonfossil fuel sources like solar and wind, classified as renewable resources due to their wide availability and limitless energy supply, installing such resource-based plants incurs higher initial costs compared to fossil fuel plants.However, the depletion of fossil fuel reserves necessitates prioritizing these installations despite the higher upfront expenses.In Bangladesh, solar, wind, hydro, and biomass are recognized as the primary contributing renewable resources based on the country's geographical location.As of June 2023, these sources have an installed capacity of 1183 MW, constituting only 4.5% of the country's total installed capacity. 13Among these resources, solar power dominates by contributing around 80%, including both off-grid and on-grid systems, as depicted in Figure 9.The government encourages increased installations of not only solar plants but also other renewable sources, both in the public and private sectors, to shift dependence away from fossil fuels.A master plan, illustrated in Figure 10, has been developed to progressively increase generation from these sources in the coming years. 4However, the estimated contribution of renewable energy Renewable energy portfolio: contributions by resource type. 13 I G U R E 10 Forecasted electricity generation from renewable energy resources.32,33 F I G U R E 11 Trend of energy generation from renewable resources.1,2 to total electricity demand in 2040 is projected to be only 10%, still significantly below the required amount.32 Comparatively, our neighbor India has set an ambitious target to derive 50% of its energy from renewable sources by 2030 and has already surpassed its initial goals, achieving an installed solar capacity of 64 GW by early 2023.In contrast, Bangladesh's progress in renewable energy has been slower. Despisetting a target of achieving 10% of total electricity generation from renewable sources by 2020, the country has only installed a capacity around 5% and achieved less than 1% as of 2022, depicted in Figure 11.This includes off-grid solar home systems but excludes hydro, as its contribution has remained constant throughout the period.It highlights the urgent need for accelerated efforts and increased investment in renewable energy to bridge the gap and ensure a sustainable future.

Solar energy
Sunlight contains an enormous amount of energy.In 1954, a group of scientists at Bell Laboratory invented the silicon photovoltaic (PV) cell, which can extract this energy to drive an electric device for a significant duration. 34It incorporated a sandwich of p and n type material that absorbs the photon of incident sunlight, converting it into electricity through the well-known "photovoltaic effect".It converted sunlight at a rate of 4%, which is less than a quarter of the efficiency of modern cells. 34The advanced technology allows the doping of multiple materials with poly-crystalline silicon to increase efficiency.Since a single PV cell, based on size, produces around 1-2 W at maximum efficiency, it needs to arrange in a particular fashion forming modules, panels, and arrays for large-scale power generation. 35However, the amount of generated electricity primarily depends on its incident sunlight intensity and duration.Bangladesh is a semitropical country with a geographical location 20 ′ 34 0 to 26 ′ 38 0 North latitude. 14It experiences plenty of sunlight all over the year which always encourages the extraction of a significant amount of electricity from solar energy.The country receives 4-6.5 kWh/m 2 /day of solar irradiation annually, which is moderate in intensity. 11The geographical distribution of country's photovoltaic power potential is shown in the Figure 12.It reveals that the country's Geographical distribution of photovoltaic power potential. 36

F I G U R E 13
Trend of SHS installation in Bangladesh. 36,39,40utheastern part possesses higher potential than the rest.Additionally, the Meghna estuary region has a significant photovoltaic power potential that is suitable for a substantial installation.It emphasizes installing the solar system in both domestic and commercial sectors, which will be technically and economically viable.However, almost 70% of people lacked access to electricity due to inadequate infrastructure and the scattered essence of rural accommodations in the year 2000.Therefore, the Bangladeshi government planned to establish the solar home system (SHS)s in rural areas where most of the population lived.As a result, the government working with several international partners, including the World Bank and GEF, installed roughly 12,000 SHSs in 2003 as part of its development goal to guarantee all citizens have access to electricity. 37It sparked an entrepreneurial spirit in 40,000 villages resulting in an improved livelihood for rural people.Later, the program was actively supported by 56 partner organizations, including GPOBA, JICA, IDB, USAID, ADB, KfW, GIZ and so forth, making it one of the world's most effective off-grid electrification initiatives. 38This program installed 6,037,642 SHSs with a capacity of 263.5 MWp by December 2022 in distant locations where gird extension is difficult and expensive to implement. 38It benefits approximately 20 million people, roughly 12.5% of the total population.The annual and cumulative SHSs installation is illustrated in Figure 13.Though installation was costly and commercially unpopular, it reflects a gradual rise in the early stages.However, it has acquired immense popularity in recent years as a result of subsidizing programs and beneficial policies implemented by the government and other contributors.Since kerosene was used for lighting the house at night in rural areas, this program saves consumption of around 4.74 million tons of kerosene, worth $1711 million approximately. 38It also directly or indirectly involves about 75,000 people with diverse employment opportunities.
However, we are still lagging in establishing a large-sized commercial solar plant that requires considerable open space.But, it is challenging to acquire that much land space for these installments in our overpopulated country.Hence, the government always focuses on installing solar in any open space, predominantly on domestic and commercial building rooftops.Though public and private sectors have already undertaken multiple projects in distinct locations by June 2023, illustrated in Table 5 to enhance the solar contribution in future grids.Currently, ten projects (461 MWp capacity)  13 Furthermore, Bangladesh, a nation where agriculture predominates, uses 1.34 million diesel pumps for irrigation, and its annual petroleum expenditures exceed $1 billion. 39It encourages the government to devise multiple policies with subsidies to popularize solar-based irrigation instead of using costly diesel.Additionally, it gives farmers the ability to increase crop yields, assuring food security.It benefits more than 6000 farmers by installing 2828 systems with a total capacity of 53.33 MWp.Moreover, development programs also established multiple solar projects for multifarious purposes like mini-grids of 5.805 MWp, charging stations of 0.282 MWp, drinking water systems of 0.126 MWp, and solar street lights of 17 MWp resulting in 2612.11MWp total generation. 13esides this, installing solar panels in railway slabs, parking lots, 41 and floating PV 42 in riverine or coastal areas is found to be a promising option for optimizing space.But, due to the acute gas shortage in recent days, the government mandates producing 20% of the required demand from solar or other sources in all the factories and commercial buildings.It influenced Pacific Genes Group in Chittagong to install a solar plant with 3.5 MW which contributes to more than 10% of its electricity demand. 43

Wind energy
In the past, wind energy was used for many different purposes, including driving windmills, pumping water, irrigating crops, and propelling ships.But, a certain wind speed is a prerequisite in operating wind generators in producing electricity from the kinetic energy of the wind.Bangladesh's subtropical climate resulting in monsoon and typhoon seasons, favors heavy rainfall and periodically high wind speeds. 44The government and some partner organizations ran a wind resource assessment campaign to perform customized technical potential analyses from the country's geographical information.Figure 14 represents the resulting wind resource map of Bangladesh.It illustrates 20 meteorological stations, from which only 9 encompassed each of the country's four main geographic regions that participated in the measurement period from June 2014 to December 2017. 45These data assist the government in decision-making regarding wind power installment policy, investment, and subsidy.It also enhanced to lower technical jeopardy and promote private enterprise involvement in the country's emerging wind business.The assessment data was not promising for large-scale wind installments.But it inspired multiple private investors to participate in the government's effort to promote wind evolution as a local, low-emission energy resource that will fulfill rising energy needs and promote rural economic growth.However, according to accessible data, Bangladeshi lands typically experience modest wind speeds, as seen in Figure 14.But, it reflects a potential to produce wind energy in the coastal areas and on its islands.These findings led the government to build two wind-powered plants: the country's first one of 900 kWp at Sonagazi, Feni, in 2005, and another, 1 MWp, at Kutubdia, Cox's Bazar, in 2008. 46However, recent data depicted in Figure 15 from Bangladesh Meteorological Department forecasts a more significant wind power potential than previously, especially in four coastal areas: Mongla, Patuakhali, Kutubdia, and Bhola. 47It illustrates that the average wind speed has been favorable in recent years, notably from May through September, peaking in July.It provides the opportunity for high-potential investment from the government and other private organizations in establishing large-scale wind farms. 48Though, it has already become mandatory to increase these installations to enhance contributions from renewable sources in curbing the current energy crisis.However, due to meteorological limitations, Bangladesh has only extracted around 3 MW of electricity from wind and remained one of the less focused resources.But, continuous encouragement leads to its current installed capacity of 360 MWp through multiple projects in coastal regions especially in Cox's Bazar.The significantly contributed plants of the existing projects by June 2023 are listed in Table 6.Moreover, distinct organizations are still working on analyzing the feasibility of small-sized wind plants with offshore and onshore arrangements in the southern part of Bangladesh. 47,49They have already forecasted a target of 5000 MW of electricity generation from wind resources by the year 2030, including onshore and offshore farm establishment. 50t is contingent on encouraging wind speed data from an American organization covering more than 7700 square miles of surface areas.It explored a convenient wind potential at nine distinct locations in six districts, including Natore (Lalpur), Chattogram (Sitakunda, Chandpur, and Parki Beach), Mymensingh (Gouripur), Habigonj (Madhupur), Khulna (Dacop), Cox's Bazar (Inani Beach), and Rangpur (Badarganj).According to preliminary research at these places, the typical wind speed is 5-6 m s −1 at heights of more than 60-80 m, which is adequate for any small scaled wind generation. 50

F I G U R E 14
Geographical distribution of wind power potential. 45,51 I G U R E 15 Wind power potential in Mongla, Patuakhali, Kutubdia, and Bhola locations. 47

Biomass and biogas energy
Biogas, a renewable energy source derived from the anaerobic decomposition of organic matter, primarily consists of methane (CH 4 ) and carbon dioxide (CO 2 ), along with minor amounts of nitrogen, hydrogen sulfide, and water vapor.Biomass, including plant materials, wood fuels, agricultural waste, and animal byproducts, undergoes fermentation to produce electricity.Nonedible oil seeds like soybean, canola, algae, rapeseed, corn, sunflower, mustard, wheat, pulses, sugarcane, palm, and maize are commonly used for this purpose.In Bangladesh, rice husk, an abundant agricultural residue resulting from rice processing, serves as a prevalent biomass source due to the country's heavy dependence on rice production. 38Annually, Bangladesh generates over 9 million tonnes of rice husk waste from processing approximately 70% of the country's 46 million tonnes of paddy in local rice mills. 52Gasification technology harnesses this waste to produce producer gas, which powers gas generators for electricity generation.The authorities have installed two generators, one in Gazipur (250 kW) and another in Thakurgaon (400 kW), utilizing gas from rice husks.Additionally, more than 80% of rural households have adopted individual biogas plants, utilizing their daily waste to meet energy needs and reduce reliance on external sources. 53While the search for environmentally friendly and safe alternative technologies for biofuel continues, developed countries have shown increased interest in biogas power plants, particularly in managing industrial waste, especially from the poultry and cattle farming sectors.Paragon Poultry Limited in Gazipur has successfully established a biopower plant solely utilizing poultry waste, generating 350 kW of electricity from the waste of 250,000 parent stock chickens. 54This initiative not only fulfills 14-h electricity demand but also produces organic fertilizer for crop cultivation, serving as a potential model for the poultry industry.The government has approved a project worth nearly $2 million to install 64,000 biogas plants in rural areas, providing renewable energy for cooking and electricity generation. 55heir target is to establish over 83,000 biogas plants, collectively generating 0.69 MW of electricity.Collaboration between the government, Infrastructure Development Company Limited (IDCOL), and Bangladesh Power Development Board (BPDB) has resulted in various initiatives, aiming to generate approximately 50.89 MWp of electricity through biogas and 0.4 MWp through biomass by June 2023, as listed in Table 7. 13 These efforts not only contribute to the grid network but also bring electricity to remote areas.The byproducts of biogas and biomass offer numerous socio-economic advantages.Biogas slurry, obtained from the anaerobic fermentation of livestock and poultry manure, serves as a liquid organic fertilizer that can replace chemical fertilizers in field applications through drip irrigation systems. 56This promotes soil health, improves crop yields, and enhances product quality.Additionally, the utilization of biofuels for cooking improves the quality of life for rural households.With 70% of rural residents lacking access to natural gas connections, they rely on expensive wood and kerosene stoves.Biogas plants provide a promising alternative by saving forests and reducing health risks, particularly for rural women.The government has initiated efforts to promote clean cooking and offer clean fuel options to rural households.Majpara Union in the Pabna district has become the country's first "biogas union," utilizing biogas burners for cooking, saving on fuel expenses, and mitigating health hazards associated with wood-burning stoves. 57

Hydro energy
Hydropower, utilizing the kinetic and potential energy of water, stands as the most cost-effective energy source in Bangladesh.The country's abundance of rivers with substantial water flow serves as a catalyst for hydroelectric plant installations, although the construction of infrastructure such as dams and reservoirs incurs significant capital costs.Currently, the solitary operational hydropower facility in Bangladesh is the Kaptai plant, commissioned in 1962, which has consistently generated 180 MW of electricity on a daily basis without noteworthy breakdowns or major refurbishments. 13evertheless, the government intends to augment its capacity by establishing two additional 50 MW units, thus elevating total production to 330 MW to optimize performance during the rainy season. 8Multiple surveys and investigations have been conducted to identify suitable locations for small-scale hydropower installations, resulting in the identification of viable sites including Foy's Lake in Pahartali, Choto Kumira in Chittagong, Sealock in Bandarban, Nikhari Chara and Madhab Char in Baralekha, Moulavibazar, Ranga Poni Gung in Jaintiapur of Sylhet, Bhugai Kangsha in Nalitabari, Marisi in Sherpur district, Punarbhaba and Talma in greater Thakurgaon, and Pathraj in Dinajpur. 58The researchers assessing these sites suggested that the Chittagong-Bandarban area could generate an approximate annual production of 1.16 GWh, while the Mymensingh-Sherpur district could yield 6.31 GWh, and the greater Dinajpur-Rangpur area could produce 1.87 GWh.Although riverine Bangladesh possesses a hydropower potential of about 1600 MW across the Karnaphuli, Sangu, Matamuhuri, and Brahmaputra river basins, it presently exploits only 12% of the available water resources.
Research indicates that damming the Sangu River at Tarasa Chara could create a reservoir with a capacity of 1,900,000 acre-ft, facilitating power generation of approximately 82 MW.Another viable site, Champatoli, could support the construction of a compacted earth-filling dam over the Matamuhuri River, offering an installed capacity of 17,500 MW.Furthermore, the Teesta barrage project, established in 1990, holds promise in generating 125 GWh of electrical power, with an additional 19 potential hydropower sites identified.In addition to these endeavors, the hilly regions of Rangamati, Khagrachari, and Bandarban present numerous streams suitable for small-scale hydropower generation through the development of storage facilities.Moreover, the high tide of rivers and canals reaching the Bay of Bengal in southern regions are utilized for electricity generation, ranging from 5 to 300 kW. 59

CHALLENGES AND PERSPECTIVE ACTIONS
Bangladesh is gradually progressing toward renewable energy development despite multiple constraints related to the power sector.The current energy crisis forces the government to identify and synthesize these constraints to ensure the optimum utilization of renewable sources.The government and private sector stakeholders need to work together to resolve and set the goals for this development. 60The following section summarizes the multiple expert opinions that identify the obstacles to developing presently contributing renewable sources in Bangladesh.

Policy issues
Bangladesh's government has already placed multiple policies to integrate renewable energy into the traditional grid network to achieve the targets set out in the master plan of 2016. 61It introduces tax incentives and promotes private sector participation in the power sector primarily through renewable energy installations.In contrast, most current regulations and rules are ambiguous and have no real-world implications for investors and developers in this volatile global context. 62owever, it significantly assists the government in minimizing the supply-demand difference compared to the last couple of years due to considerable contribution from small power plants owned by the private sector.But current energy scenarios compel the authority to emphasize large-scale grid-connected renewable energy installments, which demand more attractive incentives for the private sector.Since existing policies did not focus on new technology-supported large-scale projects, it needs to be revised for long-term benefits. 7Project developers also faced a lack of guidance regarding the acceptable tariffs for these highly invested systems.It demands more subsidy in terms of offered tariffs by the energy purchasing authority due to the higher cost of production in renewable energy projects compared to low-cost gas power stations.As a result, a more holistically developed policy is a prerequisite to address the preeminent bottlenecks and the entire renewable project's financial aspects.

Lack of land resource
Bangladesh is a country of 57,321 mi 2 with a population of 166 million. 63Its economic growth primarily depends on agriculture.According to the World Bank collection of development indicators, 76% of the country's available land area (50,259 mi 2 ) is occupied by agricultural establishments like cropland, forest, tea estates, saltpans and so forth. 64Contrarily, urban and industrial regions, accreted lands, and rural communities all fall under the category of nonagricultural land.However, the increased population has already diminished a significant amount of cultivable land in the last few years.It forced the government to limit agricultural land usage other than food production to ensure food security.It also mandates the developers to use nonagricultural land for any renewable energy project establishment without clarifying any specific definition of these small available land areas. 65Moreover, there is no proper guidance regarding optimizing agricultural land through these projects.But, large-scale renewable projects like solar farms require a significant portion of land areas, that is, 5 acres for a 1 MW generation. 41It is comparably less (around 1 acre) for a similarly sized wind farm.Therefore, it has become challenging for developers to manage that much land in developed areas.Hence, they are consequently forced to acquire land in undeveloped areas, primarily along riversides in the country's northwest, khas land, and the coastal regions, including islands in the country's south, with limited infrastructure and access. 61These areas usually don't have access to the national grid, raising concern for the grid-tied installment and increasing the cost of the projects.However, land acquisition for public or privately owned projects is not straightforward due to the complex procurement process.Besides that, most landowners are also unwilling to sell or lease their lands since it reflects social status. 66he government is the only body with the authority to purchase any land or property for essential public purposes.They need to assist the developers in purchasing or leasing from several hundred landowners.Moreover, available lands in the coastal regions are prone to flooding in the rainy season due to the anticipated effects of climate change.Respective government authorities should provide the necessary support to conduct erosion protection establishments for the developers.Therefore, developers demand to address all these issues explicitly in revising the energy policy and regulations.

Upgrading grid network
The government has planned to increase its generation capacity to harmonize with future demand.It defines the location of the future generation unit, which demands establishing the required infrastructures to evacuate the generated power.But, large-scale renewable energy projects are not yet synchronized with the existing infrastructure.Moreover, most of these projects are expected to be located in islanded or coastal regions where the expansion of the grid network, like transmission infrastructure, is a prerequisite. 67This penetration also demands a significant increase in the existing grid capacity.However, developers face difficulties extracting the national grid information for conducting technical and feasibility studies.Since this information is not readily available, it forces them to rely on donor organizations' data involving other work.It demands government assistance in establishing harmony between the transmission authority and developers in installing these projects.However, renewable energy sources' essence is intermittent and unpredictable, whose generation fluctuates over short periods depending on the wind's direction or speed and the sunlight's intensity. 68In order to support the high demand during the absence of these sources, the authorities must take spinning reserves into account.These resources are interconnected through a controlled power electronic (i.e., inverter) circuit during grid-tied operation, which produces the required voltage and frequency for grid synchronization. 41But intermittent essence makes it challenging to reproduce appropriate network parameters.However, large-scale penetration of these also raises concerns about traditional grid stability, reliability, and protection issues, as already seen in other countries using renewable sources dominantly.Since Bangladesh's national grid has not been exposed to any large-scale intermittent sources penetration, it requires a detailed technical study to explore the existing grid's robustness or reliability.In addition to that, renewable sources are usually operated in unity power factor mode for maximum energy extraction, which forces to ensure reactive power support from other sources for stable grid management.However, multiple countries prioritize battery storage systems for this support and act as a backup during intermittent energy supply from renewables.However, no research has yet been done on how well the country's grid will hold up to changes in system frequency and voltage brought on by integrating substantial renewable energy-based power plants. 61As a result, developers demand a clear vision of these challenges while planning the installment of large renewable projects in Bangladesh.Moreover, due to a lack of knowledge about renewable energy sources, the respective authority needs to emphasize training the grid operators on managing intermittent energy on the grid.The government should also assess the effect of infrastructure development on grid expansion while imposing a wheeling tariff for renewable energy generation.

Inadequate resource data
Multiple local organizations and academic institutes have undergone numerous feasibility studies to map country's renewable energy resource potential.They have measured solar irradiance and wind speed in different locations, which are not publicly available and have not yet been validated by any national authority.Apart from this, a few international organizations, such as NREL, and UNDP, have estimated wind and solar data using data explorer, a geospatial tool based on satellite model approximation. 61These assessment studies played a vital role in the investment and deployment decisions of the existing renewable projects.But information on resources, such as measures of seasonal change for sun irradiation and wind speed in certain places, is required by developers.They also expect government support in validating the assessment reports for mapping or zoning country's renewable energy projects based on real potential.However, the southern coastal area has a high potential for wind energy despite being vulnerable to natural disasters, including flooding, cyclones, storm surges, erosion and so forth. 67It forces developers to study weather data in assessing project establishment considering these vulnerabilities.

Financial aspects
Governmental organizations in Bangladesh, such the IDCOL have played a crucial role in solar energy establishment, especially solar home systems and other off-grid installations, over the last two decades. 61Renewable energy projects are increasingly financed by numerous commercial and development institutions.But their lack of experience in handling the associated risks of these projects makes it challenging for the new developers.Moreover, the lack of other sources to provide finance, high quoted interest rates from lenders, and short loan tenors that do not match the renewable energy project's cash flow profiles further exacerbate the issue.As a result, developers demand government support or commitment through policy to enhance this credit mechanism, especially for longer payback periods compared to conventional plants.The cost of renewable plants is cheaper than fossil fuel plants.However, renewable energy installation costs are now increasing after years of decline due to escalating costs for materials, transportation, and labor.But, expenditures for coal and gas-supplied plant facilities are rising even more quickly due to the rise in global energy prices brought on by the Russia-Ukraine war.According to recent research, worldwide different plant's average electricity generation costs per MWh are as follows: onshore wind farms ($46), substantial solar farms ($45), coal-based plants ($74), and gas-fired plants ($81). 69During the last few years, a significant amount of investment from commercial banks has been deployed for fossil fuel-based plant establishments while reaching their credit limit for other power sector investments.It also raises concerns for new developers in finding financial sources.Moreover, there is no established standardized procurement program for renewable-based projects.As a result, it offers unrealistically short time frames for bidding and processing, discouraging international developers. 67The government must support developers based on required credit enhancement mechanisms in financing renewable energy projects, such as sovereign guarantees.A well-planned bidding procedure with an open and transparent appraisal of offers to ensure participation from local and foreign developers should be their top priority.Therefore, these problems must be addressed in new policies laying out an explicit methodology for higher tariffs, tax exemptions, and lowering import charges.

Institutional support
Bangladesh is steadily progressing with renewable energy projects, primarily due to inadequate institutional capabilities within the public and commercial entities.It also experiences a lack of coordination between multiple government institutions.The government should involve multiple educational institutes while assessing renewable energy projects in distinct locations through funding opportunities.It will strengthen this renewable sector by improving local capabilities and technical skills.Government institutes like Sustainable and Renewable Energy Development Authority (SREDA) and IDCOL primarily promote and disseminate information on sustainable energy. 61But they must quickly develop a work plan to enhance knowledge and institutional capacity within public utilities and academic institutes.It should focus on energy security, energy generation trends, energy storage, renewable energy project assessment, procurement, grid stability, and protection issues during inverter-based resources integration.

CONCLUSION
The socio-economic development of Bangladesh is presently hindered due to inconsistent electricity supply in the industrial and domestic sectors.This paper illustrates that it is primarily due to the lack of natural gas reserves required for generating a significant amount of electricity.The unregulated use of gas and the unavailability of new gas fields raise more concerns about this generation for future years.In addition, the rising price of coal and oil in the global market force government to lean on electricity generation from renewable sources through multiple master plans.They are promoting renewable resources at optimum levels to meet the rising demand and reduce the stress on fossil fuel plants, especially natural gas.As a result, the government has already applied scheduled load-shedding and shutting down the market at night to save gas for future use. 69Moreover, low foreign exchange reserve forces to avoid importing costly fuel to mitigate the energy crisis.On the other hand, numerous encouragements resulting in Figure 16, which represents the operational, ongoing implementation, and under-planning renewable energy projects in different locations in Bangladesh, are forecasted to be completed by the year 2030.Accumulation of these projects will contribute to slightly above 10% of the total demand in the year 2030, which is lower than the required due to the possibility of out of supply from natural gas-based plants, resulting in a scary future.This paper highlights the scope of promoting renewable energy sources especially solar, wind, hydro, and biogas, more extravagantly due to the geographical advantages.It summarizes the key findings and explicitly discusses potential barriers in establishing large-scale renewable energy-based plants.These barriers may vary across countries but need to be resolved while increasing renewable energy penetration through public and private organizations.The government and the respective authority should also need to assist the developers by enforcing revised policies and regulations.They have already implemented a variety of subsidies and financing programs with favorable terms to viable renewable energy installments and ensure overall energy security.Additionally, by adopting a holistic approach and prioritizing alternative energy options, Bangladesh can mitigate the adverse impacts of declining gas production, reduce greenhouse gas emissions, and build a resilient and self-sufficient energy sector to support industrial growth in the future.

F I G U R E 7
Trend of energy generation from coal resources.1,2 3as supply and demand forecast in million cubic feet per day (MMCFD).3 TA B L E 1
13lar Park Projects in Bangladesh13, eight projects (435.32MWp capacity) are in the ongoing implementation phase, and multiple projects (1310.34MWp capacity) are in the planning phase.These massive installments will contribute 2406.66MWp as solar parks, and 144.37 MWp as rooftop solar to the future grid.
TA B L E 5 13,46plant projects in Bangladesh.13,46Biogas and biomass plant projects in Bangladesh.13 TA B L E 6