Present Situation of Electrical Energy Demand, Supply, Projection of Demand-supply and Renewable Energy Utilization and Progress

—A brief overview of present electricity demand, supply, projection of them and renewable energy generation and progress has been presented in this paper. Electricity is the major source of power for most of the country's economic activities. According to the Bangladesh Power Development Board in July 2018, 90 percent of the population had access to electricity. However per capita energy consumption in Bangladesh is considered low. The country has a very limited energy reserve; small amounts of oil, coal and countable natural gas reserves. The country suffers an internal energy struggle, as about 88% of the country’s power producing thermal plants are gas-based. To solve this problem, renewable energy is being used.


I. INTRODUCTION
Electricity is the major source of power for most of the country's economic activities.Bangladesh being a developing country, the electric energy demand has been increasing at a significantly high rate as well as electric energy supply has been increasing but the state-owned electricity utilities suffer from large energy shortages. The electricity Demand in the system varies one hours to other hours. The maximum demand is occurred during 5 pm to 11 pm which is termed as 'peak hour' and other part of the time is termed as off-peak hour. The extent of this variation is measured in terms of Load Factor, which is the ratio of average and maximum demand. For economic reasons, it is desirable to have a higher Load Factor, as this would permit better utilization of plant capacity. Moreover, the cost of energy supply during peak hour is higher, because some relatively costlier power plants are required to put in operation during the peak hour. For these reasons, load management is essential throughout the year for better capacity utilization of power plants and minimum generation cost.
In the time of Nawab Khwaja Ahsanullah, electrification of the capital city Dhaka began in 1901, only 19 years after New York and 13 years after London. [2] Later, an Electricity Directorate was established in East Pakistan in 1948. There were few Steam Turbines in Siddhirganj (maximum size 10MW), Chittagong and Khulna area at that time. In 1962, 40 MW Kaptai hydroelectric project was installed a 132kV transmission line between Dhaka and Chittagong was commissioned. [8] In 1971, after the independence of Bangladesh only 3% of the population had access to electricity. In 2010, Shikalbaha and Siddhirganj power plant start to generated 255MW and also start to generated 520MW in some private sector. About 1763MW electricity add in national grid and captive power. It has been increased to 59.6% in 2012. However, 79 % percent of the connected consumers suffer from load-shedding, and 60% of the consumers face low voltage supply. In 1974-75, the installed electricity generation capacity was 667 MW whereas in August 2016 it was 12780 MW including the 600 MW power import from India. Bangladesh's total installed electricity generation capacity (including captive power) was 15,351 megawatts (MW) as of January 2017 [4] and 15,500-megawatts in 2018 [6]. The 88% of the population had access to electricity in 2018. [6] There are 52 public power plant in 2019 which generated about 8,845-Megawatt electricity.
The total installed capacity is 20,000 MW (combining solar power). Bangladesh's energy sector is booming.
The present government is committed to ensuring access to affordable and reliable electricity for all citizens by 2021. Recently, Bangladesh started construction of the 2.4gigawatt (GW) Rooppur Nuclear Power Plant expected to go into operation in 2023. Also start construction of 7,554 MW power plant (such as Matarbari Power Station, Payra Thermal Power Plant, Rampal Power Plant, Feni Lanka Power Limited, Payra LNG Power Plant). Bangladesh will need an estimated 35,000 MW power by 2030. Bangladesh Government has undertaken various projects to meet this rapidly growing demand. They propose some new power plant. Our government is expecting to fill-up all shortage of electricity supply after completing these projects.

II. ELECTRICAL ENERGY SYSTEM IN BANGLADESH
Electrical energy system discusses about mainly generation & supply sector, demand sector, consumption sector. The supply sector is categorical as commercial energy and biomass fuels. The commercial energy comprises of natural gas, oil and electricity while the biomass fuels are agricultural wastes, animal wastes and fuel wood. In the demand sector, energy consumers make decision to utilize gas, oil and electricity based on both fuel price and the availability of the fuels whereas the biomass fuel consumption is mainly based on the availability of biomass fuels. The supply sectors (commercial and biomass) are the fuel supplies and imports. The imports are equal to the shortfalls in domestic supply.

A. Electrical Energy Generation
The power sector has experienced considerable progress in meeting the demand for electricity. Access, coverage, and level of consumption have significantly increased over the years. Daily load shedding has significantly dropped. Natural gas and coal are the main sources for power generation in the country. About 62.9% of Bangladeshi generated electricity comes from natural gas, while 10% is from diesel, 5% comes from coal, 3% of heavy oil, and 3.3% is of renewable sources. [2] There also some power plants are under construction and some are proposed. Total installed capacity was 15,953 MW which includes 4,452 MW IPP/SIPP, 1745 MW Rental Power Plant & 251 MW in REB (for PBS) and 660MW Power Import from India. The maximum peak generation was 10,958 MW which was 15.60% higher than that in the previous year. The reasons for lower peak generation with respect to generation capacity were: (i) some plants are out of operation for maintenance, rehabilitation & overhauling (ii) capacity of some plants dated due to aging and (iii) gas shortage.
Total net energy generation in FY 2018 was 62,678 GWh, which was about 9.43% higher than previous year's net generation of 57,276 GWh. Net energy generation in the public sector was 31,082 GWh and 26,813 GWh in the private sector (including REB). Another 4,783 GWh was imported from India through the interconnection in Bheramara and Tripura.
The list of power plants in Bangladesh is given below: Import from Tripura 100MW Import 3. Import from India 40 MW Import GRAND TOTAL 15,953 Total 10154 There is some proposed power plant. These power plant will start electricity generation within next few years. When all of proposed power plant start generation of electricity, we hope that there will no load-shedding occur.   The demand and supply curve show that the shortage of electricity in present. So, some time we face load shedding. It also shows that we can fulfil our all demand in 2032. In 2035, we hope some extra electricity will generate after fulfil all demand.

II. CONSUMPTION PATTERN OF BANGLADESH
Most of the energy consumption occur in domestic and Industrial sector. [6] According to the Bangladesh Power Development Board Energy Consumption Pattern of our Country is given in table: The table show that about 53% electricity consumption by domestic uses and 33% electricity consumption by industrial uses and 0nly 14% electricity used by Agricultural and commercial fields.

III. DISTRIBUTION SYSTEM LOSS
In 1991, Distribution loss in Bangladesh about 40% but present it reduce to only 10% in 2018. [2,3,6,13] Total system loss (Distribution and Transmission loss) last 12 years is given below: In 2006, the total system loss 21.25% which is a large loss in our system. These losses can be reduced to 11.87 % in 2018.

RENEWABLE ENERGY
The source of gas and fuel are limited that is why the government taken some step to use renewable source to generate electricity and already started some project such as Teknaf Solar Park, Sutiakhali, Mymensingh Solar Park, Sunamganj Solar Park.
Now Bangladesh generate only 550 MW electricity from renewable sources. Targets of power generation capacity by 2030 from renewable energy source given below: [1,2,10,13]

Scope of Renewable Energy:
Solar PV: Bangladesh is subtropical country. The daily solar radiation is 4-6.5 kWh/m2. So, it makes the use of solar panels very effective . The government introduced a scheme known as solar home systems (SHS) to provide electricity to households with no grid access.

Wind:
The average wind speed in Bangladesh between 3-4.5 m/s. There is a good opportunity in island and coastal areas for the application of wind mills for pumping and electrification.

Biomass:
The common biomass resources available in Bangladesh are agricultural crop residues, wood residues, animal waste and municipal solid waste, etc.
Biogas: Bangladesh has the potential to generate 5204 Mm3 of biogas which could add around 7.30 GWh electricity to the national grid. The energy starved Bangladesh needs to promote biogas technology to reduce the dependence on conventional energy system as well to ensure energy security for the future.
Hydro-electric: Power can be produced through using the gravitational force of falling or flowing water. It is the most widely used form of renewable energy.The dam at Kaptaimukh, built on the River Karnafuli in the Chittagong Hill Tracts (CHT), is the only hydroelectric power project in Bangladesh.

NEWTON'S EXTRAPOLATION
Extrapolation is a type of estimation, beyond the original observation range, the value of a variable on the basis of its relationship with another variable. The formula of newton's extrapolation s given by:

Demand and Supply projection
Newton's Extrapolation is linear extrapolation but our past data is not linear so we should be considering some factor such as transmission loss, Distribution loss, System losses, Target of renewable energy use and use of captive power. We consider decrement when calculated grid demand, Kd which depend on captive power use (such as personal solar, Biogas etc.) and consider increment when calculate grid supply, Ks which depend on reducing transmission loss, distribution loss and target of renewable energy used. For projection of demand, For projection of Supply, We determine some projection of demand and supply up to 2036. This projection show that we overcome from storage of electricity in 2034. The demand and supply curve show that the shortage of electricity in present. So, some time we face load shedding. It also shows that we can fulfil our all demand in 2035. In 2036, we hope some extra electricity will generate after fulfil all demand.

ACKNOWLEDGMENT
First of all, we would like to express our heartiest thank to almighty Allah to give us blessing and opportunity to complete this project successfully. Then we express our gratitude and thank to our honorable project supervisor Professor Dr. B. K. Bala, Dean, Faculty of Engineering, BSMRSTU for sharing his absolute expertise and valuable time. We are also grateful to different online sources from which we collect a lot of information.

CONLCUTION
In this paper, we have briefly discussed about electrical energy situation in Bangladesh-demand, supply and future projection. According to the research, total electricity supply is almost 15000 MW whether total demand is more than supply [3]. The government have taken some steps to balance this demand and supply. We also projected energy generation till 2036 regarding to the generation improvement. We have calculated that the total grid power generated in Bangladesh is 8845 MW and total captive power generated is 6197 MW [1,3]. As the energy sources are limited, renewable energy sources are also been used. If we use of captive power, reduce system, distribution and transmission loss and use targets of Renewable Energy, we hope to solve shortage of electricity and our projection will be successful.