Advanced science, Bangladesh, Economic, Environmental, International, Technical

Harnessing the Solar Energy absorbed by ocean waters

solar_energy

The world’s oceans constitute a vast natural reservoir for receiving and storing solar energy. They take in solar energy in proportion to their surface area, nearly three times that of land. As the sun warms the oceans, it creates a significant temperature difference between the surface water and the deeper water to which sunlight doesn’t penetrate. Any time there’s a temperature difference, there’s the potential to run a heat engine, a device that converts thermal energy into mechanical energy.

Most of the electricity we use comes from heat engines of one kind or another. The working principle of such an engine is very simple. It operates between two reservoirs of thermal energy, one hot and one cold. Energy is extracted from the hot reservoir to heat a working fluid which boils to form high-pressure vapour that drives a turbine coupled to an electricity-producing generator. Contact with the cold reservoir re-condenses the working fluid which is pumped back into the evaporator to complete the cycle.

The idea of building an engine to harness energy from the oceans, mainly to generate electricity, by exploiting the thermal gradient between waters on the surface and deeper layers of an ocean is known as OTEC—acronym for Ocean Thermal Energy Conversion. With OTEC, the hot reservoir is an ocean’s warmer surface water with temperatures, which can exceed 25 degrees Celsius, and the cold reservoir is the cooler water, around five to six degrees, at a depth of up to one kilometre. The working fluid is usually ammonia, which vaporises and condenses at the available temperatures. This is analogous to choosing water as the working fluid matched to the temperature differential between a fossil-fuel-fired boiler and a condenser cooled by air or water.

The maximum efficiency of a heat engine operating between reservoirs at 25 and 5 degrees Celsius is 6.7 percent. This means efficiency of an actual OTEC engine will be much less, perhaps 2-3 percent. But low efficiency isn’t the liability it would be in a fossil-fuelled or nuclear power plant. After all, the fuel for OTEC is unlimited and free, as long as the sun heats the oceans.

The greater is the temperature difference, more efficient an OTEC power plant would be. For example, a surface temperature of 30 degrees would raise the ceiling on efficiency to 8.25 percent. That’s why the technology is viable primarily in tropical regions where the year-round temperature differential between the ocean’s deep cold and warm surface waters is greater than 20 degrees. The waters of Bay of Bengal along the shores of Bangladesh, a country that enjoys a year round warm, and at times very hot weather, have excellent thermal gradients for producing electricity using OTEC technology.

The world’s biggest operational OTEC facility, with an annual power generation capacity of 100 kW, was built by Makai Ocean Engineering in Hawaii. Tokyo Electric Power Company and Toshiba built a 100 kW plant on the island of Nauru, although as much as 70 percent of the electricity generated is used to operate the plant.

The US aerospace company Lockheed Martin is building an OTEC electricity generating plant off the coast of Hainan Island in China. Once operational, the plant will be able to generate up to at least 10 MW of power, enough to sustain the energy requirements of a smaller metropolis. India is building a 200 kW plant, expected to be operational before 2020, in Kavaratti, capital of the Lakshadweep archipelago, to power a desalination plant. Other OTEC systems are either in planning or development stage in Iran, Kuwait, Saudi Arabia, Thailand and several countries along the Indian Ocean, mostly to supply electricity.

Like any alternative form of energy, OTEC has its advantages and disadvantages, but the advantages outweigh the disadvantages. Among the advantages, the one that stands out is its ability to provide a base load supply of energy for an electrical power generation system without interruption, 24/7/365. It also has the potential to produce energy that are several times greater than other ocean energy options, such as waves and tides. More importantly, OTEC is an extremely clean and sustainable technology because it won’t have to burn climate-changing fossil fuels to create a temperature difference between the reservoirs. A natural temperature gradient already exists in the oceans. The gradient is very steady in time, persisting over day and night and from season to season. Furthermore, the desalination technology as a by-product of the OTEC can produce a large amount of fresh water from seawater which will benefit many island nations and desert countries.

However, recirculation of large volumes of water by OTEC power plants could have negative impacts on the aquatic environment. In particular, the introduction of nutrient-rich deep waters into the nutrient-poor surface waters would stimulate plankton blooms that could adversely affect the local ecological balance. Additional ecological problems include destruction of marine habitats and aquatic nursery areas, redistribution of oceanic constituents, loss of planktons and decrease of fish population.

Since OTEC facilities must be located closer to the shores due to cabling constraints, they could have significant effect on near-shore circulation patterns of ocean water. As a result, open ocean organisms close to the shores will be especially affected because they are known to have very narrow tolerance limits to changes in the properties of their environment.

The biggest drawback of OTEC is its low efficiency. This implies that to produce even modest amounts of electricity, OTEC plants have to be constructed on a relatively large scale, which makes them expensive investments. It’s the price we should be prepared to pay to curb global warming. Industry analysts however believe that in the long run, low operation and maintenance cost would offset the high cost of building OTEC facilities.

The current effort, as agreed in the 2015 Paris Accord, to keep our planet lovable is like taking one giant step backward before trying to move one step forward. If technology for OTEC and other eco-friendly renewable sources of energy are fully developed and globally commercialised, it would indeed be one giant step forward in mitigating global warming. They would also equip communities worldwide with the self-empowerment tools that are required to build an independent and sustainable future.

 

The author, Quamrul Haider, is a Professor of Physics at Fordham University, New York.

Bangladesh, Economic, Environmental, International, Life as it is, Political

Politics of climate change, sinking Bangladesh and floating houses

Climate change is real and permanent. There is no turning round as we have gone past the point of no-return. It can only get worse from here. Climate change is, therefore, an existential threat for our children and grandchildren for whom time is running out fast.

Floating house in BangladeshApparently, it isn’t a threat for those who abdicated leadership of a warmer world and yet formulate environment-damaging energy policies from the luxury of their cooler world—air-conditioned homes and offices. If they cared even a bit about their progeny, they wouldn’t be flying in ozone-layer-depleting private planes or riding fossil-fuel-guzzling stretched limos and SUVs.

A few world leaders led by Donald Trump believe that carbon dioxide makes the earth greener instead of creating climate crisis. Consequently, Trump deleted references to “climate change” from government websites, fired scientists from advisory boards and the Environmental Protection Agency. He seized on the uncertainty in climate models to reverse greenhouse gas emission regulations of the Obama administration and withdrew the United States from the 2016 Paris Agreement on curbing global warming. He even nonsensically blamed this year’s out-of-control California fires on environmental laws. Other climate change deniers are his bagful of deplorables, the well-paid operatives of organisations that take contributions from fossil fuel corporations and a colourful cast of self-styled “experts” who have made a living out of rejecting the scientific evidence of climate change.

They are perhaps not aware that one of the most alarming but reliable projections for global warming has been made by researchers at the prestigious Carnegie Institution of Science in Stanford in California. The results of their research, based on a decade’s worth of satellite observations concerning the net balance between the amount of energy entering and leaving the atmosphere, have been published in the December 2017 issue of the high impact, peer-reviewed journal Nature. They concluded that if large emissions of greenhouse gases continue unabated throughout the century, worldwide temperatures could rise nearly five degrees Celsius between 2081 and 2100.

It is an undeniable fact that episodes of raging wildfires, high-category hurricanes, ferocious cyclones, floods of biblical proportions, deadly mudslides, severe droughts, bone-chilling Arctic blasts followed by lethal heatwaves and the melting of Arctic ice at a rate never before seen are effects of a sub-one degree rise in global temperature since 1880. Heaven only knows what will happen if we, as agreed upon by the 2016 Paris Agreement’s stakeholders, take the free pass of heating up our planet by two degrees before the end of this century.

Even a two-degree rise in global temperature would most likely set the stage for the greenhouse effect to spin out of control, eventually triggering a runaway greenhouse effect whose impacts would be cataclysmic, to say the least. Nevertheless, scientists at the Intergovernmental Panel on Climate Change believe that there is virtually no chance of a runaway greenhouse effect being induced by human activities, despite the fact that greenhouse gas emissions are still moving in the wrong direction.

What triggers a runaway greenhouse effect? The increase of atmospheric carbon dioxide and water vapour, two of the dominant greenhouse gases, would raise the global temperature which, in turn, would cause more water from the oceans to evaporate and carbon dioxide stored in the soil and oceans to bake out. This would be in addition to the carbon dioxide produced by burning fossil fuels. The positive feedback of continued emission of these greenhouse gases would ultimately snare our planet into a vicious cycle of a runaway greenhouse effect, which was responsible for raising the surface temperature of Venus to a blistering 480 degrees Celsius—hot enough to melt lead.

One of the countries that is already paying a hefty price for the climate sins of industrial nations is Bangladesh. It is predicted that the two-degree boost in temperature and the subsequent rise of sea levels would sink the coastal areas of Bangladesh, thereby resulting in an unprecedented human tragedy. Already, the intruding sea has contaminated groundwater which supplies drinking water for coastal regions and degraded farmlands, rendering them less fertile and at places completely barren.

Although engineering adaptations to climate change have been successful in other countries, such as the dikes constructed in the Netherlands, they won’t work in Bangladesh because the soils are sandy and constantly shifting. Thus, if the country does not want to see millions of her climate refugees migrating inland and ending up in decrepit slums, then the government should take a serious look at the “Dream House”—a flood-resistant floating house—built by a team of BRAC University students.

The concept of floating houses and floating villages is not new. There are many such villages in the world. They are communities with houses and other amenities of a town built on top of large raft-like structures or on stilts, as in the Tonlé Sap Lake in Siem Reap in Cambodia.

Floating houses in Bangladesh’s coastal areas could save the lives and livelihoods of millions from the catastrophic effects of anthropogenic climate change. Bangladeshi farmers have already developed techniques for building floating farms, known as “dhaps,” with duck coops, fish enclosures and vegetable gardens anchored by ropes to the riverbanks where the water rises at least three metres during the monsoon season.
The arduous life of the people living in the floating dwellings that would gently rock and roll with the ebb and flow of the Bay of Bengal would not only be a paragon of adapting to climate change but also a modern-day example of Darwin’s “survival of the fittest.”

 

The author, Quamrul Haider, is a Professor of Physics at Fordham University, New York.

 

 

Advanced science, Astrophysics, Bangladesh, Economic, International, Technical

Orbit of Bangabandhu-1 and other satellites

May 12, 2018 is a red-letter day in the history of Bangladesh. On this day, “Bangladesh started a glorious chapter in the history with the launching of Bangabandhu-1 satellite,” President Abdul Hamid said in a message to the nation. Indeed, Bangabandhu-1 added a new milestone to the path of continued advancement of the country. Proudly displaying the flag of Bangladesh on its solar panels, the satellite is orbiting the Earth in a geostationary orbit located at 119.1 degrees east longitude.

The physics of a satellite’s orbit is remarkable. For our current knowledge of orbital motion, we owe tons of gratitude to Johannes Kepler who, in the early 17th century, relentlessly pursued the planetary orbits by putting the Sun at the centre of ‘his’ Universe. In this pursuit, he gave us three laws of planetary motion that endure to this day. Of particular interest to the motion of satellites is his third law, which states that the square of a planet’s orbital period (in years) is equal to the cube of the planet’s average distance (in astronomical unit) from the Sun. One astronomical unit is the average distance of Earth from the Sun, which is approximately 150 million km.

By working with his laws of motion and the universal law of gravitation, Isaac Newton found that Kepler’s third law is a special case of a more general law. He showed that in addition to the cube of the average distance of a planet from the Sun, square of the orbital period is also inversely proportional to the mass of the Sun. Moreover, according to Newton, the orbital speed of a small object orbiting a much more massive object depends only on its orbital radius, not on its mass. Accordingly, if satellites are closer to Earth, the pull of gravity gets stronger, and they move more quickly in their orbit.
The speed, however, depends on the mass of the massive object. That is why an astronaut does not need a tether to stay close to the International Space Station during a space walk. Even though the space station is much bigger than the astronaut, both are much smaller than Earth and thus stay together because they have the same orbital speed.

Satellites can be placed in different kinds of orbit – geosynchronous, geostationary, Sun-synchronous, semi-synchronous, orbit at Lagrange points.When a satellite is placed in a ‘sweet spot’ where, irrespective of its inclination, it orbits the Earth in the same amount of time the Earth rotates with respect to the stars, which is 23 hours 56 minutes and 4 seconds, it would appear stationary over a single longitude in the sky as seen from the Earth. This kind of orbit, where communication satellites are placed, is called geosynchronous orbit.

A special case of geosynchronous orbit is the geostationary orbit, which has a circular, geosynchronous orbit directly above the Earth’s equator. Besides communications, both orbits are also extremely useful for monitoring the weather because satellites in these orbits provide a constant view of the same surface. Using the rotational time and known mass of the Earth, we find that the orbital radius of a geostationary orbit is about 42,220 km from the centre of the Earth, which is about 35,850 km above the Earth’s surface.

Just as geosynchronous satellites have a sweet spot, satellites in a near polar orbit have a sweet spot too. If the orbits of these satellites are tilted by about eight degrees from the pole, a perturbing force produced by Earth’s oblateness would cause the orbit to precess 360 degrees during the course of the year. Satellites in such an orbit, known as Sun-synchronous or Helio-synchronous orbit, would pass over any given point on the Earth’s surface at the same local time each day. Additionally, they would be constantly illuminated by the Sun, which would allow their solar panels to work round the clock. Orbiting at an altitude between 700 and 800 km with an orbital period of roughly 100 minutes, satellites in a Sun-synchronous orbit are used for reconnaissance, mapping the Earth’s surface and as weather satellites, especially for measuring the concentration of ozone in the stratosphere and monitoring atmospheric temperature.

Many Global Positioning System (GPS) satellites are in another sweet spot known as semi-synchronous orbit. While geosynchronous orbit matches Earth’s rotational period, satellites in semi-synchronous orbit, at an altitude of approximately 20,000 kilometres, are in a 12-hour near-circular orbit. With a smaller orbital radius, a satellite would have a larger coverage of ground area on the Earth’s surface.

Other orbital sweet spots are five points located on the Earth’s orbital plane. The combined gravitational force of the Earth and the Sun acting on a satellite placed at these points, known as Lagrange points, would ensure that its orbital period is equal to that of Earth’s. Hence, the satellite will maintain its position relative to the Earth and the Sun.
The two nearest Lagrange points, one between the Earth and the Sun and the other in the opposite direction of the Sun, each 1.5 million km away from the Earth, are home to many space-based observatories. Some of them are the Solar and Heliospheric Observatory designed to study the internal structure of the Sun, the Deep Space Climate Observatory producing accurate forecasts and providing warning by monitoring dangerous space-weather conditions, and the Wilkinson Microwave Anisotropy Probe measuring the cosmic background radiation left over from the Big Bang.
The writer is a Professor of Physics at Fordham University, New York.

Bangladesh, Cultural, Environmental, Life as it is, Political

Well done, Sir!

Dhaka trafficThe The on-duty police officer pleads with a flag-carrying car on Hare Road on June 6. The photo was shared on the ‘Traffic Alert’ Facebook Group. COURTESY: SHAMOL JAHANGIR HUSSAIN.On-duty police officer pleads with a flag-carrying car on Hare Road on June 6. The photo was shared on the ‘Traffic Alert’ Facebook Group. COURTESY: SHAMOL JGIRIN

There are iconic pictures that sometimes capture an age, define a moment in history, exemplify beauty, tragedy, or joy, in ways otherwise impossible to evoke. Who can forget the naked, screaming Vietnamese girl fleeing the napalm attack on her village in 1972; the Chinese man standing in lonely defiance in front of a column of tanks at the Tiananmen Square in 1989; the Times Square kiss; or the raising of the US flag at Iwo Jima, heralding the end of WWII?

The picture published in The Daily Star on June 7 on Page 3 of a police officer pleading with a flag-bearing car to not go the wrong side of the road certainly does not have the same drama or historical resonance. But it is remarkable nonetheless for it not only portrays the exemplary integrity of the officer but also reveals a subtle but stark truth about our political realities. The first gives us hope, the second makes us cringe.

We can be justifiably proud of the fact that an officer could, on his own cognisance and authority, exert the supremacy of law and insist that even the privileged classes follow the standard procedures established for everyone else. This is most reassuring. Moreover this took place in a posh area. The people who live or visit here are the ministers and secretaries, power brokers and high rollers, the insiders and deciders. This is where wealth and power seduce each other, and remain locked in intimate, if illicit, embrace.

These are not people used to hearing the word “no”, or being stopped, or being told that they are engaging in an illegal act, or being made to feel accountable for their actions, or (heaven forbid) being asked to correct their behaviour or reverse their decisions. Power in Bangladesh is usually defined, and often expressed, as the ability to flout the law and face no consequences, or as Erich Segal had put it in Love Story in a slightly different context, “never having to say you are sorry.”

Thus, driving on the wrong side of the road becomes a metaphor of our political times. It is an “in your face” raised middle finger which indicates both an entitlement that is casually assumed, and an attitude that is sneeringly demonstrated.

The reason the picture acquires such enormous significance is because it contradicts our typical experiences and expectations. We are not generally used to the rule of law being duly respected and publicly enforced. In these matters we are more likely to being disappointed and, sometimes, outraged. We read of the increasing numbers of extrajudicial killings in the country where those entrusted with enforcing the law take upon themselves the roles of prosecutor, judge and executioner all rolled into one. We also see pictures of stricken family members holding up photographs of people who have “disappeared”.

Some of these supposed “victims” in both groups are/were presumably horrible individuals who deserve to be removed from our midst. But, no amount of public anger and frustration about supposedly “bad people” can, ever, justify the suspension of the human rights and liberties guaranteed in the constitution. We must never forget that the concept of democracy entails a nation governed by law, not a nation governed by “men” (however well-intentioned the latter may be).

The public confidence in the rule of law is also a bit shaken by the lack of enthusiasm in bringing the full force of the law against the high and mighty. There are the bank-swindlers, the land-grabbers, forest-cutters and water-polluters, the money launderers, the drug kingpins, the local “investors” who park their money in dodgy deals and shady holdings abroad, the real estate scammers, the tax evaders, the corrupt contractors offering shoddy work at inflated prices, and the ubiquitous “gatekeepers” of the rentier state who command its resources and extract payment for services to which citizens have a right. These people are not particularly concerned about being “caught” and, in fact, flaunt their (mostly ill-gotten) wealth in rude and taunting swagger.

Moreover, the citizens see inordinate delays in the investigation of crimes and bringing perpetrators to justice. In the last several years alone the murders of young Taqi in Narayanganj, college student Tonu in Comilla, journalists Sagar and Runi in Dhaka, and many progressive bloggers and social media activists, remain shrouded in ambiguity and confusion.

Crimes against women and minorities are particularly vulnerable to foot-dragging and seeming indifference. The attacks on temples and ashrams, or communal violence in Ramu in Cox’s Bazar, Shantia in Pabna, Nasirnagar in Brahmanbaria, Thakurpara in Rangpur, or Longadu in Rangamati, have not seen much prosecutorial headway. Similarly, of the 4,541 allegations of rape brought to the much-vaunted one-stop crisis centres over the last 16 years, only 60 have been found guilty. And when one is both a woman and “indigenous” (e.g., Kalpana Chakma who was abducted in 1996), the wait for answers can be long and cruel.

The clogged and sluggish nature of the legal system was revealed in the law minister’s own statement in Parliament in January 2018, when he indicated that there were more than 3.3 million cases pending in courts, with more than 476,000 in the High Court Division and 16,565 in the Appellate Division of the Supreme Court. More importantly, almost a million cases have been languishing for more than five years. Not only does this provoke the old dictum of “justice delayed is justice denied” but it also indicates a court system almost overwhelmed by the pressures put on it.

There are also some public concerns about the use of law enforcement agencies as partisan instruments serving the agendas of particular governments, rather than as autonomous institutions serving the interests of the State. Cases may be initiated or withdrawn because of political considerations (even indemnifying entire classes of crimes committed at certain times), and judicial orders may, at times, be held in abeyance. In an unprecedented affront to the Courts, it is even possible for an individual, who had been duly charged, convicted and sentenced for a capital crime by the legal system, to receive a political pardon and then be spirited out of the country in the cover of darkness.

But this litany of criticisms and complaints should not blind us to the fact that most law enforcement personnel are generally honest, dedicated and competent. They toil in thankless, often dangerous tasks, are usually overworked and underpaid, and receive little appreciation even when they take huge risks and make personal sacrifices to uphold the principles of law and justice. Moreover, the system has to contend with a colonial legacy which had defined its structures and priorities; struggle with inadequate resources, training and incentives offered to it; and function within a larger moral environment which neither rewards nor encourages integrity and talent. To expect these people to be saints, when most others around them are not, is both unrealistic and unfair.

However, it is undeniable that there are some widespread anxieties and scepticism about the rule of law in the country. It is in this particular context that this picture is so memorable and the officer so heroic. He serves to reaffirm our faith in the system, and reminds us once again that there are honourable people in law enforcement willing, and daring, to do the right thing.

The only aspect of the photograph that is bit awkward, but which also speaks volumes, is that the officer has his hands folded in front of him in a traditional gesture of submission and forgiveness-seeking. Sir, it is the occupant of the vehicle who should be assuming that posture, not you. The law is on your side. So are we. Stand tall.

 

The author, Ahrar Ahmad is the director-general of Gyantapas Abdur Razzaq Foundation.

 

Bangladesh, Cultural, International, Life as it is, Literary

Origin of Bengali Calendar and the celebration of ‘Noboborsho’

cc614c7fe3b876a539e58a314e7a94c5[1]Only three more days to go before another Bengali New Year (also known as Noboborsho), year 1425 on the 14th of April 2018, ushers in sweeping away the misery and pain of the past year. Welcoming the Noboborsho (also known as Pohela Baishakh i.e. the first of the Bengali month called Baishakh) is a very joyous occasion in Bengali culture and it is very much steeped in tradition. That tradition overrides any religious divide, narrow sectarianism and tribalism.

The day normally starts with boys and girls, men and women, all waking up early in the morning before the sun-rise. They are all dressed in bright colourful outfits and women are donned in bright yellow saris and garlands in their hair. The women carry garlands in their hands as they walk the streets, as if to offer garlands to the exalted souls of the New Year and they chant Noboborsho-welcoming songs. As the sun rises, they would welcome the new day ushering in the new year and pray in songs and kirtons that the new year will bring peace, prosperity and happiness. The procession of men and women in convivial mood continues throughout the day and in the evening, there are theatre stages where songs (mainly Tagore songs), plays, dramas etc. are presented.

The Noboborsho (New Year) is not just the beginning of a year in Bengali tradition, it is the beginning of a new chapter, a new undertaking in life. In olden days (before the creation of Pakistan), the Noboborsho would also see the beginning of a new book – a business ledger – for the traders, small businesses or even professionals such as teachers, doctors, engineers etc. For them the new book was like a diary where past experiences, present accomplishments and future aspirations are all depicted. And, as usual, no big occasion in Bengal would go without distribution of sweets!

There used to be a Ponjika – a short printed book giving major events of the next one year and guiding people through thick and thin of their lives. Altogether, Noboborsho is the culmination of the past year and the beginning of a new year, both of them are of equal significance.

This tradition stretching back centuries was temporarily interrupted by the new state, Pakistan, which was created in 1947 on the basis of religious doctrines. Since the Bengali language and culture evolved over the centuries in the land where Hindus and Muslims (as well as Buddhists, Jains and so forth) lived side by side, Islamic fundamentalists of Pakistan felt threatened by this long-held tradition. They insisted that Bengali language, Bengali tradition are all Hindu tradition and Muslims of Bangladesh should avoid, indeed boycott, these things and become ‘true Muslims’ by adopting Pakistan’s Urdu language. For the Bengali Muslims, it was like tearing up the age-old tradition and identity for the sake of imported religion. This conflict eventually led to the breakup of Pakistan and thence Bengali Muslims reclaimed their tradition and identity now.

Even now, nearly fifty years after the creation of Bangladesh on the basis of language and culture, there are strident calls by the over-jealous Islamists within the country to stop celebrating Bangla Noboborsho on the plea that it is anti-Islamic and blatantly Hinduism. Even the Bengali Calendar is viewed as anti-Islamic practice. These religious bigots preach things without any shred of knowledge and understanding.

The view that Bangla Noboborsho and Bangla calendar are imports from Hindu culture to Muslim Bangladesh is not only blatantly communal and racist, but also grossly misconceived. This assertion on the basis of religious bigotry could not be farthest from the truth.

Let me give a brief background of the history of Bengali Calendar and how the 14th of April came to be used to usher in the Noboborsho, 1425 BS (Bangla Sôn).

The third Mughal Emperor, Muhammad Akbar (also reverentially addressed as Akbar the Great), was a great reformer and instrumental in promulgating a new Bengali Calendar after modifying the then existing calendar. He did so in order to facilitate the administrative procedures and to fix a firm tax collection date in Bengal.

At that time, the calendar that used to be utilised was known as Tarikh-e-Elahi, which followed the Islamic lunar calendar. The lunar year consists of twelve months, but has 354 or 355 days (following 12 lunar rotations round the earth). Thus, there is a drift of about 10 or 11 days every year between the lunar and solar (Gregorian) calendars. That created a major practical problem. A fixed date for the collection of taxes from the farmers and peasants, normally set at the end of a harvest period, gradually came forward by about 11 days every year and fell out of season.

That meant that whereas a tax collection date might have been originally fixed after the harvest period gradually drifted forward and became a date prior to the harvest after just a few years. That created immense misery to the farmers to pay taxes before the harvest! Realising this serious practical problem, Mughal Emperor, Akbar along with the royal astronomer, Fathullah Shirazi developed the Bengali calendar. It was a synthesis of Islamic lunar calendar and the modern solar calendar.

The year Akbar took over the reign of the Mughal Empire was 1556 AD (Gregorian Calendar). That year in Islamic calendar was 963 AH (Anno Hegirae). He promulgated that a new calendar would be started on the 1st of Muharram (which is the first month of the Islamic Calendar) in that year of 963 AH. Following that system, the year would follow the solar year (365 days) and so no mismatch between the new calendar and the seasons would arise from that time. That calendar came eventually to be known as the Bangla Calendar with Bangla months such as Boishakh, Jyoishto etc. assigned to it.

However, that calendar was slightly revised during the Pakistan days by a committee headed by Dr Mohammad Shahidullah under the auspices of the Bangla Academy in 1966. That revised version (when 14th April was fixed as the beginning of the year) was adopted officially in Bangladesh in 1987. That is the calendar that ushers in the Bengali Noboborsho.

Now the question is how do we get to the year 1425 BS on the 14th of April 2018 AD? The following consideration would show how it is done.

As the start of this calendar was 1556 AD (Akbar’s accession to the throne), which was also the beginning of the Islamic year 963 AH, 462 years (2018 AD – 1556 AD) had passed since then until now. Now adding 462 years to the Islamic year of 963 AH (when the system started), we get 1425. This is how we have the incoming New Year of 1425 BS this year.

Also, one can analyse the difference between the Bengali Calendar and the Islamic Calendar. The Islamic year now is 1439 AH, whereas the Bengali year is 1425 BS. The time when divergence took place was in 1556 AD and during these intervening 462 years (2018-1556) the Islamic calendar fell short by 462 x 11 = 5082 days with regard to solar calendar. This then produced over 14 years (5082/355) in Islamic calendar. In other words, an extra 14 years were produced in the Islamic calendar since the commencement of the Bengali calendar, and that explains why it is 1439 AH, but in Bangla calendar it is 1425 BS.

The adoption and modification of calendars are done by many countries – Islamic or non-Islamic – to suit their needs.

Islamic Republic of Iran uses the Solar Hijri Calendar, called the Sham Hijri (SH), which begins with the vernal equinox (the start of spring in the northern hemisphere). The length of time between vernal equinox and autumnal equinox is about 186 days and 10 hours and the other cycle is 178 days. Afghanistan uses a slight variation of the Iranian calendar. West Bengal uses a Bengali calendar where the Noboborsho is on 15th of April.

Thus, any claim that the Bengali Calendar belongs to a Hindu religion or culture and that adoption of this calendar is un-Islamic can be categorically rejected. Such assertions are utter rubbish and pure bigotry.
A. Rahman is an author and columnist.