Energy Systems

The term energy is used constantly, from energy drinks to energy saving to nuclear energy, we are often hearing this term. But what is energy really? How is it formed, how is it used and where does it come from? This article will give a basic description of how energy works and where it comes from in a way that is not too complicated.

What Is Energy

In common terms, energy is the ability to do work. Work is what happens when any type of force acts upon an object, regardless of whether it is a short or long distance. There are two forms of energy, kinetic and potential. Kinetic energy is the energy that is used by motion, and potential energy is energy that is stored and has the 'potential' to be used. Almost all useful energy is kinetic for this reason. Heat is the total amount of stored energy in an object and it tells us the amount of stored energy which is in an object. Temperature is the average amount of potential energy that is in an object, and can give us an idea of the amount of energy from which can be extracted from it, depending on the temperature difference between the object and the temperature of it's surroundings 1).


Resources are the things that contain energy that we consume. These resources are generally divided into three categories, non-renewable, renewable and perpetual. Non-renewable resources are things that we cannot replace, or cannot replace over short periods of time, such as coal, gas and uranium. Renewable resources, as it's name suggests are resources that can be replaced over a short period of time, such as timber and fisheries. Perpetual resources are always available in abundance irrespective of whether we use them or not, such as sunlight, wind and lunar tides. Resources can be depleted to the point of scarcity or disappearance, recycled and used for other uses or re-used as long as the original use has not damaged or degraded them 2).

__Non-Renewable Resources__

Non-renewable resources can be depleted by the means of extracting them from the earth, such as coal. In most cases the extraction process will stop before it is completely exhausted due to the rising costs creating lower demands. If the non-renewable resource can be recycled, it can continue to be used after depletion, such as plastic and glass recycling. There is also the possibility that a depleted resource can be substituted for something similar, for example using plastic pipes instead of copper pipes.

__Renewable Resources__

Resources that are renewable have the unique ability to be able to replace themselves after being taken or depleted. A good example of this is fish and fisheries. If harvested sustainably, the fish will always continue to breed and numbers will return to normal. This may also be the case in some types of timber forests, however this is not always the case when it comes to certain species of trees. If the harvesting goes too far, the resource can become non-renewable and extinct. Renewable resources can also be used for recycling.

__Perpetual Resources__

Perpetual resources are unique in the way that they can never run out or be depleted. These resources can be harnessed and used for little or no energy cost, and will always be there no matter how little or how much we use.

__Resource Abundance__

Resources can be abundant or scarce, or they can lie somewhere in between. Many people regard things as water as an abundant source, however a lot of resources that were once considered abundant are now scarce, so nothing should be taken for granted. There are some resources that are scarce which we can still utilise to some extent, however some things that are on the brink of extinction cannot be utilised at all, such as blue whales. The use of these resources has a tendency to get more expensive the scarcer they get, as it gets harder to extract the resource or they have been substituted with something more cost efficient 3).

__Resources We Use__

There are several types of resources that humans use. This can include direct solar power such as photovoltaic, indirect solar power such as wind and geothermal power, biological resources such as wood, peat, coal, gas and oil, tidal power, geothermal power and also nuclear power. Over half the world depends on biomass for their energy and power needs, and this is a concerning statistic seeing as the resources are finite. Up to 75% of the world's energy consumption is made up of non-renewable resources such as coal, gas and timber 4). Resources can also be classified by their quality, or the amount of energy that they can provide. High quality materials have low entropy, meaning that the amount of energy used to convert the resource to quality energy is low.


There are three laws when it comes to thermodynamics. The first one is that energy may be transformed, but it can never be completely destroyed. The second law is that whenever energy is converted, it will always be downgraded to lower quality energy, hence the entropy of the resource will always get higher. The third law is that as the entropy of a resource increases, the value will become more stable as the temperature nears zero. Many scientists have been trying to find the key to perpetual energy for hundreds of years and have not had success to date. It must be noted that whilst energy can never be totally destroyed, the amount of useful energy can always run out 5).

Types of Non-Renewable Resources

As discussed above, around 75% of the world's energy consumption currently comes from non renewable resources. Many types of non-renewable resources have taken several millions of years to form, and at current rates of use, unless we switch to alternative means of electiricty production, we will face serious shortages by the mid 2040's 6).


Wood is one of the most used biomass resources. Although it is considered to be a renewable resource, unsustainable use has started to turn this into a non-renewable resource. This resource is generally used in third world and less developed countries and mainly in the form of charcoal which is used for heating and cooking. If wood is used sustainably, it is an efficient and cheap means of energy production especially when burnt in contained furnaces such as pot belly stoves, however it causes high rates of emissions and pollution. Most of the developed countries have banned the use of timber as a heating method due to pollution concerns, however some countries such as Sweden use timber for commercial heating from sustainably grown forests under controlled conditions 7).


Peat is the remnants of mosses and plants that have become trapped in extremely wet areas often referred to as 'peat bogs'. It is mostly used for heating of domestic homes, however in some countries it can be used to fire power stations. Peat is a clean burning, low emission resource however peat bogs are not very widespread worldwide and are also home to fragile ecosystems.


Peat Bog in Ireland 8)


Coal was the resource responsible for sparking the industrial revolution in the 1800's. There are some very large deposits of coal worldwide mainly in China, Russia and the United States, however the supplies are now dwindling and extraction is starting to become more energy intensive. There are different qualities of coal, ranging from lignite or brown coal, to bituminous coal to anthracite of black coal, which is of the highest quality, or lowest entropy. The burning of coal, especially lower quality coal can cause high CO2 emissions and has been identified as a major contributor to global air pollution and carbon dioxide increases 9).

__Natural Gas__

Out of all non resources, natural gas is considered to be the cleanest and most efficient. Natural gas is found in pockets trapped above petroleum deposits and is mainly made up of methane, but can also have quantities of butane and propane. It can be liquefied and used for commercial and domestic use safely, and has very little emissions or pollutants. Most of the known natural gas deposits are in the middle east and Russia with also a great volume locked in the permafrost around the Arctic circle. Natural gas burns hotter than most other resources, however has higher potential for exploding and is not as stable as some of the others 10).


Oil, or petroleum is known as the fuel of the 21st century, and humans have become increasingly dependant on it, especially for transportation systems such as motor vehicles. Most of the world's known deposits of oil are found in the middle east region, however there are smaller localised pockets worldwide. Only about 40% of oil in a well is accessible as it becomes too energy intensive to go any deeper. Oil is a finite and non-renewable resource, and it is expected that we will run out of oil by around the year 2080, however increases in technology may see producers be able to re-tap old wells and extract oil from the remaining 60% of the wells. Oil and petroleum produce high levels of pollution and emissions, and can also contribute to producing acid rain 11).


Some of the other types of non-renewable resources include oil shale, which is sedimentary rock which is high in hydrocarbons called keregon. It is currently too energy intensive to refine and convert oil shale into a usable form of energy. Another one is tar sand, which is oil that has become so thick that it is become semi-solid and cannot flow. Most deposits of tar sands are too deep down to be of any practical use, however there have been deposits found closer to the surface, especially in Canada where it has been used to supplement their oil supplies.


Oil Shale in Canada 12)


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