Month: November 2017

Climate is the average daily weather over a long period of time in a particular location. It is changed by both anthropogenic causes and natural phenomena such as volcanic eruptions and variations in solar radiation. Any change in the statistics of a climate system is commonly known as “climate change”. Anyhow, the term “climate change” is usually used to refer the anthropogenic climate change or change in the climate system due to human activities.

Climate scientists analyze some external measures such as ocean sediments, tree rings, ice cores and pollen remains to uncover the hidden history of climate. Recently, they ascertained that the earth’s climate has changed many times over long periods of time in the past. However, it has not abruptly changed in the previous millennium until the industrial revolution began and there was a certain pattern in the climate system which preserved the living beings including flora and fauna on this planet.

As we all know, climate conditions on the earth are decisive factors in determining the earth’s habitability. Unfortunately, it has been changing at an unexpected rate after the industrial revolution. This recent change in the climate system cannot be explained by natural phenomena alone and is attributed to various destructive human activities.

Human activities that gave birth to a new formidable term “climate change”.

As mentioned above, current change in the climate system is predominantly manmade. Though there are many different anthropogenic causes of climate change, burning of fossil fuels seems to be the most terribly damaging cause. By burning fossil fuels, we release tons of heat trapping gases into the atmosphere at every point of time thereby increasing the amount of heat trapping gases in the atmosphere. This increase has resulted in a gradual increase in global temperature (global warming) and eventually unforeseen change in the entire global climate system that we experience today.

As we have already experienced, climate change affects health, agricultural industry, oceans, forests, economy and almost all the things on the earth. Climate scientists expect more frequent extreme events as we are pumping more and more pollutants into the atmosphere. More extreme events mean more deaths and more damages.

Climate change is not just another change but an aggravating issue which seems to be an origin of a massive devastation soon. Even a small change in the climate system could lead to a broad range of natural disasters such as frequent floods, heat waves, typhoons, heavy rains, wildfires, storms, droughts and many more. Some extreme events may be caused by natural phenomena. But most of these extreme events and disasters may be caused by anthropogenic climate.

Figure: Storm clouds

“Climate change” and “global warming” are interchangeably used in many contexts but have different meanings. Climate change explains alterations occurring in the global climate system in numerous ways whereas global warming is just one indicator of the changing climate. Global warming is simply the long-term increase in the global average temperature and is the most dominating, most damaging sign of the changing climate. Global warming leads to most of the natural disasters and extreme events. In next post, we will discuss the global warming from top to bottom.

1.4 Tidal power

If you live in a coastal area or if you have ever been to a beach, you might have realized that the ocean is a massive reservoir of water with an unimaginable capacity!

The ocean is a really playful place.

Even though the deep sea looks like a calm place the ocean turns to be a wildly overwrought tiger in some locations especially, in the shallow areas.

It interacts with the wind, the Sun and the Lunar leading to different types of disturbances in the sea level and morphology of the ocean.

As we discussed in the previous article, the interaction between the ocean and wind results in ocean currents and waves. In this article, we will discuss another form of ocean energy: Tides!

Tides are formed as a result of the gravitational interaction between the earth and moon. Of cause…. The gravitational interaction between earth and the Sun also causes tides but not as powerful as the tides that caused by the Lunar (Since we are far away from the Sun).

As we all know it, the moon revolves about the earth. Water in the oceans is pulled by the moon’s gravity when moon located just above the ocean. As a result, high tides occur on two sides of the earth simultaneously as shown in above figure. Low tides occur as a compensation, on another two opposite sides at the same time as shown in the same figure. The rise and fall of the sea level that occur twice a day are called tides.

Unlike other forms of ocean energy, tides represent neither direct solar energy nor indirect solar energy. Anyway, tidal power is also a renewable source of energy since tides are continually being replenished naturally. In other words, like all other renewable energy sources, tidal power would never be exhausted.

As long as the earth and noon exist tides would flood onto the shore and recede!

General background

Tidal power has a well-matured technology with a long history compared to any other form of ocean energy. Some countries have already built tidal power barrages to generate electricity.

The first tidal barrage was born in Germany in 1912. However, it was damaged in World War I, unfortunately [1]. One of the famous and oldest tidal barrage built as early as 1966 at La Rance in France is still generating electricity with a power capacity of 240 MW [1, 2]. So it gives an exciting example of a successful tidal barrage built 5 decades ago.

Worldwide tidal power potential has been estimated at 3 TW. Obviously, we can’t install the tidal power devices everywhere since tidal power is highly site-specific. Simply, there are some technological and practical limitations in tidal energy harvesting. Only a few areas in the ocean are technologically and economically viable. Some areas are technologically suitable but are economically impracticable. These technological and economic challenges largely limit the amount of energy that could be harnessed from tides. It has been estimated that less than 3% of the global tidal power capacity is suitable for power generation [2, 3].

It is equal to 90 GW of power!

Some important facts about tidal power

• Tidal power has already become commercially viable and is already being used to generate electricity in commercial scale (France, South Korea, Canada, etc.) [1, 4].
• Several countries are planning to build tidal barrages in near future (the UK, South Korea, Russia, Canada, etc.)
• Garolim tidal power station in South Korea would have a capacity of 500 MW once completed.
• Although worldwide tidal power capacity is 3 TW, the maximum power that could be harnessed would not exceed 90 GW due to technological, environmental, social and economic limitations.

Remark: Global energy demand was around 17.5 TW in 2010 and it would reach 63 TW by next century (2100) according to the recent estimations [5].

• 1 TW= 1000 GW
• 90 GW 5 % of current global energy demand. 

So, what can we conclude?

Tidal power is a renewable energy source. It releases no harmful emission to the environment and therefore, does not intensify the climate change or global warming. However, the practically viable power capacity from tidal power is extremely limited compared to the current global energy demand.

[5] Hu, A., Levis, S., Meehl, G. A., Han, W., Washington, W. M., Oleson, K. W., and Strand, W. G. (2016). Impact of solar panels on global climate. Nature Climate Change, 6 (3), 290-294.

1.2 Ocean currents

Ocean currents or marine currents are generally caused by wind, braking waves, salinity gradient and temperature gradient. As we realized earlier, wind and waves are forms of indirect solar energy. Both salinity gradient and temperature gradient represent the ocean thermal energy absorbed from solar energy by the oceans. So as we can see, ocean currents are also an indirect form of solar energy. They are connaturally formed and therefore, is a renewable source of energy.

It is needless to say both wind and ocean currents transport a huge amount of energy from one place to another. However, ocean currents transport can carry a large amount of energy per volume than winds (Note that density of water is 800 times that of air).  So we can expect a significantly higher amount of power per area (W/ m^-2) from ocean current conversion devices than that of wind turbines.

But…Ocean currents are still not widely being used to generate electricity though wind is widely being used especially in the Europe. This is largely due to technological challenges, high initial cost and site-specific nature of ocean currents. So, current energy harvesting technologies would have to be further developed prior to implementing them in commercial scale.

1.3 Ocean waves

Waves are usually generated by the winds blowing over the oceans transferring energy to the sea water. They are continually formed since oceans are frequently influenced by the winds. Once waves are formed, they roll into the coast and are reflected back into the ocean. The energy gained by the ocean from winds appears as kinetic energy of water that linked to the waves.  Since wind is an indirect form of solar energy, ocean waves also represent an indirect form of solar energy.

Ocean waves attracted a lot of attention as a potential source of renewable energy especially, during the energy crisis of the 1970s. However, wave power is not still being widely used.

Why?

There are some serious technological challenges, environmental impacts and some other drawbacks associated with wave power.

• Oceans cover 71% of the earth’s surface from the North Pole to the South Pole and Hawaii to the Marshall Islands. However, wave energy is not viable to be harvested in most of the parts in the world. It is practicable only in certain locations. Simply, wave power is inherently site-specific.
• Many wave power technologies have already been developed. But… None of them is cost-effective compared to photovoltaics, wind generators or hydro power plants.
• Wave power devices installed in the shallow sea may disturb the vessels.
• Most of the wave harvesting devices employ moving mechanisms. So, they could be harmful to the marine lives. Further, the noise produced by the machines may be highly unpleasant when the devices are installed in the coastal areas.

So,

What can we conclude?

Does wave power still offer an environmentally friendly renewable source of energy?

Yes of course!

Though wave power harvesting may result in environmental damages to a certain extent it is still environmentally benign compared to fossil fuels. Importantly, new wave power technologies are being developed to minimize the environmental impact and to make it cost-effective. Unlike fossil fuels, wave power would never run out. Throughout the day, throughout the year…They would be being created.

Wave power is still an untapped energy source. Though it is still an unpopular renewable energy source some countries such as Portugal, the UK, the USA, and Australia have already installed commercial-scale wave power harvesting devices while some other countries are planning to implement wave power harvesting projects in near future.

The worldwide wave power potential has been estimated to be about 2 TW [1]. It is equal to 10% of the world’s total power demand and is equivalent to two thousand coal-fired power plants each with a capacity of 1000 MW. So, global wave power potential at its full capacity can potentially shut down 2000 coal-powered power plants thus cutting an enormous amount of greenhouse emissions. Anyway, the contribution of global cumulative wave power capacity would be negligible even at its full capacity by 2100 as world’s power demand would have exceeded 63 TW by next century [2].

In next article, let us discuss the potential of other renewable energy sources and their practical capacities.

Earth, the third planet of the solar system is one and only known planet where life exists. Its water, fertile soil, the composition of the atmosphere and appropriate surface temperature make it a habitable place. Unlike any other member of the solar system, earth’s elegant waterfalls and lakes, lovely flora and fauna, fascinating forests and mountains, massive oceans and immensely creative ecosystems make it a magical place to all the living beings. So, it is not surprising that the natural beauty of the earth and its creativity amaze we all.

Earth is a home to thousands of animal and plant species. It provides food, water, medicine and almost all our requirements. Plants, waterfalls, flowers and mountains beautify the environment while humming of the birds delights our ears. The plants satiate our stomach while water quenches our thirst. The breeze cools down the surrounding and relieves our stress. Sun lights up the whole world. Plants purify air and produce food for us while we play on the ground. Nature is really a miraculous creation which has been programmed to heal small damages itself made by us. Our ancestors dealt with the environment with a minimal damage. They consumed only a small amount of natural resources. They loved nature. They worshipped nature. They respect nature. They did not destroy forests. They polluted neither air nor water nor soil. Simply, their activities did not lead to significant environmental damages. Nature does not punish us as long as we deal with it in a sustainable way. That is why our ancestors were not tortured by nature. They were really fortunate to respire pure air, to eat uncontaminated food, to drink clean water and to experience the beauty of nature. We can learn a lot about how our ancestors dealt with the environment by studying speeches of the most famous chief of the Duwamish and Squamish tribes, Seattle [1]. They protected the environment and encouraged their people to follow them.

But what happened after the industrial revolution that took place in Europe and North America?

Industrial revolution… sounds a music to our ears. But it was the date of birth of bad luck. As we all know, it has led to numerous environmental, social, health, economic and ecological problems. We all bear witness at least to one such terrible consequence. Let’s discuss them in the next article.

Industrial revolution which happened during the late 1700s and early 1800s is simply the process in which rural, agrarian people in Europe and North America became urban and industrial. It began in the United Kingdom and soon after, spread to nearby countries changing the processes of manufacturing and eventually the whole lifestyle. During Queen Victoria’s reign in the 19^th century, Britain and most of the neighboring countries became industrial [1]. Therefore, her reign is considered to be a golden era in the human history.

During the industrial revolution, not only technology but also the society, economy and health services were developed and revolutionized. The advance in science technology paved the way to develop state of the art of manufacturing equipment and vehicles powered by either fossil fuels or electricity. The invention of steam engine and internal combustion engine turned upward down the manufacturing industry and also the transportation sector. Those inventions greatly increased the productivity with a similar expenditure of human energy. As a result, thousands of new manufacturing factories were born all over the world. Coal powered trains and then petrol and diesel-powered vehicles came onto the roads replacing the duty of horse. New electric appliances came into our homes and started to serve us replacing some of our work. All those inventions made the life comfortable and luxurious. We thought it was a revolution and so, named it an “industrial revolution”.

However, new industries and manufacturing plants required various types of materials such as iron and steel. And obviously, they required energy to power the equipment and vehicles. It was the beginning of large-scale mining for minerals and fossil fuels. We started to mine all over the earth. We did not limit it to the land. We then dived into the deep sea and started to mine the sea bed. Finally, the whole world exposed to the human beings, unfortunately. New factories and fossil fuel-powered power plants started polluting the environment in numerous ways while we have been digging the planet for resources.

Let’s take a look back at the last century. What have we done after the industrial revolution?

• We dug everywhere on the earth.
• We drilled everywhere on the earth.
• We excavated everywhere on the earth.
• We mined everywhere on the earth.
• We cut down tens of thousands of trees in the name of development.
• We destroyed thousands of forests.
• We converted most of the forests into concrete jungles.
• We polluted the air.
• We polluted the water bodies.
• We polluted the soil.
• We grabbed the dwelling homes of animals.
• We gave birth to new deserts.
• We made our own home planet a hell on earth. We are all witnesses of it.

Eventually, industrial revolution….revolutionized the human history. But the aftermath is a terrible tragedy.

Our planet will no longer be a livable place if we steadily damage the environment and disturb the environment sustainability at the current rate.

Figure 2: Cracked ground caused by drought

As the people always think of earning money and having a luxury life, they have already missed their duties and responsibilities that they have to implement for the endurance of the environment. They have done a catastrophe that highly affects the environment and that cannot be reversed ever. Nature punish us for the environmental damages made by us in various ways. For example, our prejudicial activities increase the frequency and intensity of environmental disasters such as floods, droughts, sea level rise, heat waves, cyclones, hurricanes. It has been shown that most of these extreme events and disasters are consequences of the climate change. Further, it has been clearly affirmed that human activities are the main causes of current climate change.

Climate change is responsible for many environmental problems that we face today. Therefore, we will deeply study the climate change, its causes and consequences with relevant evidence from the next article. Then, we will move onto discussing practicable solutions that we can implement to mitigate the disastrous impacts of climate change.

In the previous article, we discussed primarily natural climate change and anthropogenic climate change. Further, we realized that the global warming was just one indicator of the changing climate but was the most dominating, most damaging sign of the current changes in the climate system. In this article, we will focus on the global warming.

What is global warming?

In brief, global warming refers to the increasing trend in the average temperature of the Earth’s surface and its lower atmosphere. As we discussed earlier, it is responsible for most of the natural disasters with which we are struggling today.

In order to fight against the increasing trend of the earth’s average temperature, a concrete understanding of the global warming is needed. This requires investigating, monitoring and modeling the changes in earth’s climate system.

How to investigate the changes in earth’s climate system

Climate scientists have been closely monitoring the behaviors of earth’s climate system and deeply studying the changes in earth’s temperature exclusively after the 1950s. They use different kinds of climate models and measurements to investigate, study and model the earth’s climate. Following is results of one such study.

Graph 01: Temperature anomaly in the last century [1]

Above chart illustrates the changes in the global climate system over the past century, under three different scenarios namely measured (dotted line), human influence (red) and no human influence (blue). The dotted line represents the actual (measured) temperature anomaly over time. It can be observed that the global temperature has been gradually increasing even though some small fluctuations can be seen. The human influence on the temperature has been remarkably increasing after 1970. By analyzing the red and blue lines, one can easily realize what sort of damage to the climate system we have done. According to the chart, the human influence on the earth’s average temperature has been climbed up while the no human influence has been gradually declining. Especially, the chart reveals that the human influence has been abruptly increasing after 1985.

The sharp increase in the average temperature that we observe today is predominantly due to the anthropogenic causes. The average temperature has notably increased after the industrial revolution. In particular, it has remarkably increased after the 1950s. It has been estimated that the average temperature of the earth has risen 0.9± 0.05 ˚C at 95% confidence since the 1950s unto the present [1]. Further, the intergovernmental panel on climate change (IPCC) has forecasted a massive jump in the average global temperature by 2100. According to their estimations, the increase in the average temperature will be in the range of 1.4- 5.8 ˚C [2].

Just to make your concerns alive

An increase of 0.9 ˚C in the average temperature changed the entire climate system leading to many natural disasters and extreme events.

So…

What will happen once the temperature rises further by 1.4 ˚C (in the lowest possible scenario)?

What will happen once the temperature rises further by 5.8 ˚C (in a worst case scenario)?

It is worth thinking but attempts stopping one’s heart.

Heavy use of fossil fuels and deforestation are two main anthropogenic causes of global warming. These human activities increase the concentration of heat trapping gases in the earth’s atmosphere causing the earth to warm up. The mechanism by which the earth’s atmosphere warms the earth’s surface and lower atmosphere is technically referred to as “greenhouse effect”. Next article will focus on natural greenhouse effect its importance and the enhanced greenhouse effect.

The greenhouse effect is the process by which the earth’s surface and its lower atmospheres are warmed up. Its mechanism was first suggested by Joseph Fourier in 1824 and experimentally confirmed by John Tyndall in 1860 [1]. Since then, much effort has been devoted to fully understand its mechanism, causes and consequences.

We can easily understand the mechanism of the greenhouse effect if we know how an actual greenhouse keeps its inside warmer. In fact, the mechanism by which the warmed atmosphere of a planet warms its planet’s surface and lower atmosphere is somewhat different from the mechanism by which an actual greenhouse warms up. However, there is a stunning analogy between them.

Figure: Structure of a greenhouse [2]

An actual greenhouse warms up due to the reduced convective heat transfer. The glass of a greenhouse lets sunlight to go through them which in turn warms the ground inside. The warmed ground then acts as a heated body and emits longwave radiation (IR) thereby warming the air inside. However, the warmed air is not allowed to escape from the house as the house is almost closed. This stops the natural convection and prevents the inside from cooling. So, the eventual result is a warmer indoor.

The greenhouse effect is not a result of blocked convection but a process governed by heat-trapping gases in the atmosphere. The greenhouse gases in the atmosphere are transparent to the shortwave radiation (visible light) but opaque to the longwave radiation (IR). As a result, visible light reaches the earth surface. In this case, it is important to know that much of the solar radiation comes as visible light. A certain portion of the incident solar radiation is reflected back to the outer space by the earth’s surface. However, the remaining incident radiation warms the earth’s surface up. The hot earth’s surface acts as a black body and radiated its heat energy out. But this radiation from the earth is not allowed to escape directly from the earth’s atmosphere and is trapped by the heat-trapping gases (absorbed). The following figure illustrates how the greenhouse effect works.

How longwave radiation is trapped?

As we all know, earth’s average surface temperature does not exceed at least 50 ˚C. So, much of the earth’s surface heat radiates longwave radiation (not shortwave radiation). This can be easily understood by treating the earth’s surface as a black body whose temperature is always less than 50 ˚C. Unlike shortwave radiation, longwave radiation is absorbed by greenhouse gases even though some of the longwave radiation passes through the atmosphere. The greenhouse gases then re-emit the absorbed radiation to all directions including towards the earth. As a result, the earth’s temperature always remains at a higher temperature than that we would expect if there was no greenhouse effect. This warming effect is somewhat analogous to that of a greenhouse and therefore is referred to as the greenhouse effect.

The natural greenhouse effect is one of the key factors in determining the habitability of a planet. But human activities improve the greenhouse effect making the planet warmer than it was in the past. In next articles, we will discuss natural and enhanced greenhouse effect in detail.

Greenhouse effect caused by naturally occurring greenhouse gases is not at all harmful to the human kinds, animals or plants. It helps maintain the earth’s temperature at a mild, habitable and relatively even level.

No doubt… If there was no greenhouse effect, the earth wouldn’t have supported lives.

Let’s take a look at an example…. The moon!

The average distance to the moon from the sun is approximately the same as that of the earth. The moon has no sufficient gravity to retain an atmosphere and therefore, no active greenhouse effect. As a result, its surface temperature declines to -153 ˚C during the night-time even though its temperature may reach about 107 ˚C in the daytime [1].

See the difference!

The earth’s surface temperature would also have a very offensive variation in the daytime and night-time if there was no greenhouse effect to trap the heat from the sun in the daytime. Simply, the greenhouse effect is the temperature regulator of the earth.

Then WHY worry?

The problem arises when humans’ activities lead to boost the greenhouse effect making the effect more powerful and detrimental. We all contribute to the greenhouse effect …pumping tons of emissions into the atmosphere.

Everyday!!!

Directly or indirectly…

In various ways…..

You may be driving a car. You may be watching TV. Meanwhile…knowingly or unknowingly, willingly or unwillingly…You are enhancing the greenhouse effect and are warming the earth.

What is enhanced greenhouse effect?

Earth’s surface temperature always remains at a higher temperature than the temperature we would expect without accounting for the atmosphere’s influence on it. Earth’s atmosphere’s influence on its surface temperature is what makes it a living planet, supporting life. However, some of our day to day activities (predominantly fossil fuel burning) boost the greenhouse effect leading to the global warming. The enhanced amount of the greenhouse effect is known as the enhanced greenhouse effect which results in global warming.

So, it is obviously manmade!

Different forcing factors

Many research projects have been devoted to find out the causes of global warming, to measure the individual influence of those causes and to model the changes in the climate system.

Following graphical representation quantitatively illustrates the contribution of different forcing factors to the global warming over the last century. It can be clearly observed that greenhouse gases were the main contributors. Unlike other forcing factors whose effects are either gradually decreasing or fluctuating, the effect of the greenhouse gases on the global warming has appallingly increased over time.

Figure 1: Impacts of different forcing factors on the global warming

The most important greenhouse gases are carbon dioxide, methane, water vapor and nitrous oxide. In addition, chlorofluorocarbons and some other gases contribute to the global warming and thus are greenhouse gases.

Most of the greenhouse gases occur naturally in the atmosphere and they are not harmful to the environment as long as they are in balance. They are very important to keep the planet warm. Earth would have become a cold, uninhabitable place and therefore another dead planet if its atmosphere contained no greenhouse gases. However, when their compositions exceed the natural level, the system becomes unbalanced leading to global warming which in turn brings natural disasters and extreme events.

When we look at all these things, we can realize that the global warming has now turned into a global war since the whole world has been affected. But….. There are some potential ways which can greatly help mitigate the problem of global warming and eventually to lower the global average temperature. We all have a responsibility in the battle with global warming.

From next article, we will mainly focus on climate change mitigation and adaptation.

In previous articles, we clearly realized that both human activities and natural phenomena are responsible for the current change in the global climate system. Further, we understood that the damaging effects of anthropogenic causes are more adverse than those of the natural phenomena.

We all are struggling in the changing climate in our day to day life. As we discussed, climate change results in disasters and deadly extreme events. Droughts, floods, cyclones, heat waves and sea level rise are just a few. The increasing trend of the climate change means frequent and more dreadful disasters, more deaths and economic losses. Our future would be most vulnerable as anthropogenic greenhouse gases continue to accumulate in the atmosphere accelerating the climate change. We need to address the root causes in order to tackle or decelerate the climate change.

How to fight against climate change: Climate change mitigation

Climate change is largely governed by greenhouse gases in the atmosphere. So, almost every attempt of fighting against the climate change requires depressing the concentration of atmospheric greenhouse gasses. There are two primary approaches to lower the atmospheric greenhouse gases: Removal of greenhouse gases from the atmosphere (carbon sequestration) and reducing the emission of greenhouse gases. As a whole, any anthropogenic intervention of lowering the emissions and enhancing the sinks of greenhouse gases could be defined as a climate change mitigation strategy.

To begin with, let’s see how to remove greenhouse gases from the atmosphere. There are dozens of natural and artificial greenhouse gas removal mechanisms. Generally, both natural and artificial reservoirs which absorb and store greenhouse gases are known as sinks. Trees, oceans and soils and savanna are the most important natural sinks. Anyway, we have nothing to do with natural mechanisms of sinks. So,

Let the trees do their job.

Let the oceans do their job.

Let the soils do their job.

And let’s do what we must do.

It is our duty to enhance the capacity of sinks and minimize our emissions.

Reforestation and carbon dioxide capture at power plants would play a vital role in carbon dioxide sequestration. However, the potential of artificial greenhouse gas removing is limited in the game of climate change mitigation due to economic and technological challenges. Reforestation would be a great option but does not seem to be practical in most cases since ever-increasing human needs require more and more lands. So, the truth is that our planet is not going to accommodate more trees.

Therefore, in practice, it is clear that removal of greenhouse gases from the atmosphere is an extremely challenging task.

Now let’s take a look at the following example to see why it is challenging.

A plant would take about 40 years to sequester one ton of carbon dioxide [1] whereas you add the same amount of carbon dioxide by driving your car around 5000 km [2]. Simply, pumping a ton of greenhouse gases into the atmosphere is much easier than removing the same amount from the atmosphere.

Considering all these facts, we can conclude that the most effective way of mitigating the climate change is nothing but minimizing the emissions. In next article, let’s study most forceful strategies to minimize anthropogenic emissions.

What are the greenhouse gases and their contribution to the climate change?

Generally, water vapor, carbon dioxide (CO₂), CFC, methane (CH₄), and also nitrous oxide (N₂O) contribute to the greenhouse effect and therefore, are known as greenhouse gases.

Most dominant contributor

Water vapor is the most dominant greenhouse gas. However, the concentration of water vapor is largely determined by the atmospheric temperature. Higher temperatures promote the evaporation of water and consequently increase the concentration of water vapor in the atmosphere which in turn intensifies the global warming.

This implies that the largest contributor to the climate change, water vapor is not a root cause of global warming but a product of global warming caused by other greenhouse gases. Can you imagine?

It is a vicious cycle!

So… What is the most deleterious greenhouse gas?

Let’s take a look at the following pie chart to find out the correct answer. It illustrates the contribution of individual greenhouse gases to the greenhouse effect (Without considering the effect of water vapor). We can see that carbon dioxide alone accounts for 55% of the warming effect.

Figure 1: Contribution of greenhouse gases to the greenhouse effect [1]

Since water vapor is a result of global warming, the second largest contributor to the climate change, carbon dioxide is considered to be the most deleterious greenhouse gas.

This implies we must lower the concentration of carbon dioxide in the atmosphere in order to mitigate the climate change successfully.

How to start

To begin with, let’s see…what are the anthropogenic sources of greenhouse gases?

Greenhouse gases are produced in various human activities where power plants, vehicles, cement plants, mining plants and industries are the most dominant sources. Just take a look at the following pie chart. It shows the annual greenhouse gas emissions, in 2005, by sector. It can be seen that the electricity generation and heating make up nearly a quarter of the total greenhouse gas emissions while transportation sector accounts for 14.3% of the emissions. Further, it can be perceived that the combustion of fuels (electricity, heating, transportation, etc.) as a whole accounts for nearly 50% of the total amount of greenhouse gas emissions.

Figure 2: Annual world greenhouse gas emissions, in 2005, by sector

As we can see, fuels (crude oil, coal and natural gas) are the largest sources of greenhouse gases (especially CO₂, N₂O and SO₂) and key contributors to the climate change. So, it is obvious that our fight against the climate change requires to minimize our fuel consumption. Efficient use of energy and energy efficient appliances are proven ways to minimize the energy demand. However, rapidly increasing demand for energy requires more and more energy and thus more fuels.

Keep in mind: Even a significantly improved modern coal-fired power plant with a capacity of 1000 MW pumps six million tons of emissions into the atmosphere annually! [1]

We need to minimize the fossil fuel consumption. But we need more and more fossil fuels to fulfil the ever-increasing demand for energy since fossil fuels are our primary source of energy.

We are really on the horns of a dilemma!

How to deal with this impasse?

The short answer is searching for alternatives to the fossil fuels: renewable energy sources.

In next article, let’s focus on renewable energy sources and their importance in climate change mitigation.

Energy, the ability to do work is one of the basic needs in our daily life. We can’t think of a life without energy. We need energy to power vehicles, electrical appliances, industrial machinery, and for almost every task!

Energy exists in several forms including heat, kinetic energy, potential energy, electrical energy and light or radiation. Energy comes from various types of sources called energy sources. Our planet is abundant in energy sources though fossil fuels still play a vital role as our primary source of energy. Any alternative to fossil fuels is an alternative energy source. There are so many alternative energy sources. However, some of the alternative energy sources are non-renewable. For example, nuclear fuels are alternative energy sources but are not renewable. Once we have consumed them they are gone.

What are renewable energy sources?

Renewable energy sources are energy sources which are naturally and continually replenished in a short period of time on the human timescale. Following are the most attractive sources of energy which are currently being used or developed.

• Sunlight
• Wind
• Rain (Hydropower)
• Biomass
• Tides
• Ocean waves
• Ocean currents
• Ocean thermal energy

It is worth understanding that fossil fuels are also continually formed by natural processes but take millions of years to form. As a consequent, fossil fuels are being rapidly depleted due to our consumption. That is why fossil fuels are not considered to be renewable.

Your car would take 10 minutes to drive 15 km and would consume one liter of petrol. However, natural processes by which fossil fuels are formed would take millions of years to form the same amount of fuel.

Contribution of renewable energy to the global energy demand

Following pie chart shows the proportion of global energy production provided by different energy sources in 2013. We can see that only 19% of the world energy consumption in 2013 has been provided by renewable energy sources while 78.4% of the consumption has been provided by fossil fuels. In addition, the chart clearly shows that almost one-tenth of the world’s energy consumption or half the renewable energy capacity in 2013 has been met by traditional biomass such as wood and cow dung. Moreover, one-fifth of the renewable energy capacity has been provided by hydropower. As we can see the contribution of direct solar energy to the global energy demand in 2013 is less than 0.25%.

Figure 1: Global energy consumption by source [1]

Why is renewable energy important?

We have already discussed the detrimental effects caused by fossil fuel combustion. Further, we realized that fossil fuels are rapidly being exhausted. However, we still need energy. So, renewable energy is the best solution.

They are not depleted.

And they are abundant in nature.

They have minimal environmental effects.

Most of the renewable energy sources release only a negligible amount of emissions compared to the fossil fuels and so provide the best solution to mitigate the climate change.

Fossil fuels or renewable energy? All up to us!

Renewable energy is everywhere from our backyard to the rooftop and from the North Pole to the South Pole. But still, we heavily rely on fossil fuels and while struggling with the environmental impacts associated with fossil fuel combustion, unfortunately.

Let us discuss renewable energy in more detail in next article.

Power of renewable energy

As we discussed in the previous article, the contribution of renewable energy to the global energy demand was 19% in 2013. Today, renewable energy sources account for 23% of the global electricity generation [2].

See the gap. Fossil fuels still provide 77% of the global electricity demand.

Think of how far away we are from our dream of 100% renewable energy.

Is it possible to replace fossil fuels with renewables 100%?

Prior to answer this question, let’s take a look at some real global energy facts.

• Global energy demand was around 17.5 TW in 2010.
• This figure would reach its milestone of 63 TW by next century (2100) according to the recent estimations [1].
• It seems to be a bullish jump by more than 45 TW.

Global energy demand is not something at rest but a rapidly increasing demand.

It is crystal clear that a single source of renewable energy cannot replace the demand for fossil fuels. Nothing to worry!

There are plenty of renewable energy sources around us. They can provide more than enough energy we need. Now let’s talk about different forms of renewable energy and how much of energy they can provide us.

1. Ocean

The ocean is the largest reservoir of water as we know it. It is not only a reservoir of water but also a massive reservoir of energy and is the largest energy storage on the earth. It covers nearly 71% of the earth’s surface [3] and receives an enormous amount of solar energy throughout the day. A considerable portion of the received energy is trapped in sea water and appears as heat. In addition to the direct solar energy, oceans grab an enormous amount of energy from the wind blowing over them. This results in ocean waves. Not only that, oceans acquire a considerable amount of energy from the gravitational energy of both earth-moon system and earth-sun system. The energy gained by the oceans appear as heat, waves, currents and tides.

1.1 Ocean thermal energy

The heat trapped by the oceans (ocean thermal energy) could be used to generate electricity. Ocean thermal energy conversion (OTEC) technology takes the advantage of temperature difference exists between shallow sea water (hot) and deep sea water (cold) to generate electricity. It is needless to emphasize that the oceans are huge heat reservoirs with an incredible amount of trapped heat from solar energy. However, the practical conversion efficiency in OTEC is very poor due to the Carnot’s limitation which limits the efficiency of any heat engine. This poor conversion efficiency limits the maximum steady-state OTEC electrical power capacity to about 10 TW [4].

Compare this value (10 TW) with the current energy demand (17.5 TW) and projected energy demand to 2100 (63 TW).

(Font sizes are proportional to the value of each number)

OTEC technology would increase the renewable energy share and help alleviate the climate change to a certain extent anyway. But it is clear that current OTEC technology is not smart enough to meet the increasing energy demand even at its full capacity.

Though OTEC is an environmentally benign technology compared to the fossil fuels it still possesses some disadvantages. OTEC power plants release some toxic chemicals such as ammonia and chlorine to the surrounding. Especially, the operation of an OTEC plant may seriously affect the marine environment including marine lives.

In next article, we will talk about other sources of renewable energy and their potential to replace the fossil fuels thereby reducing our carbon footprint.