Sustainability : Energy

Sustainability : Energy - Key SQA Definitions:

• Enhanced greenhouse effect - The enhancement of the natural greenhouse effect through man-made emissions of greenhouse gases, trapping increasing quantities of heat.

• Climate change - A large-scale, long-term shift in Earth’s weather patterns or average temperatures.

Increasing Global Population and Energy Use

As the World's population has increased drastically over the last few centuries, so has our requirement for energy. We use energy in every aspect of our lives; for heating and lighting our homes, transporting ourselves and products, farming and manufacturing, communications and entertainment. 

The traditional methods of energy generation in the form of biomass (burning plant material) simply cannot provide the energy required by modern life, so we have found new (and usually unsustainable) methods to provide our energy:-

Economics & Energy 

Access to Energy sources as with all other resources is not shared equitably around the world, with certain countries dominating energy production and supply. 

An example of this are the Organisation of Petroleum Exporting Countries (OPEC). OPEC countries hold ~80% of the World's proven Crude Oil reserves, and work together to control oil prices globally, by managing supply in a 'cartel' arrangement. 

The video below show a news arcticle explaining the function of the OPEC arrangement:-

Society & Energy

In order to provide sufficient energy for a country, sometimes very difficult social decisions must be made. An example of this can be seen in many locations around the world where settlements have had to be abandoned and submerged to make way for Hydro-Electric reservoirs. 

FOr example in China, the Three-Gorges Dam project led to the displacement of over 1.24 million residents as 13 cities, 140 towns and 1350 villages were either flooded or partially flooded by the reservoir behind the dam:-

The same can be seen within Scotland as well, with villages being submerged beneath the water when reservoirs have been built. 

Over the Autumn of 2021, after a period of drought in Scotland, the reservoir at Glendevon in Perthshire's water level dropped so much that previously submerged buildings began to emerge from the water:-

The Environment & Energy

As well as the social and economic impacts of increased Energy demand, there is also an environmental impact. These environmental effects can range from local, such as the contamination or destruction of a habitat due to, for example, mining up to the global effects of the 'Enhanced Greenhouse Effect' and Climate Change. 

'Enhanced Greenhouse effect' & Climate Change

Climate change refers to changes in the Earth's average temperature. These changes occur naturally over time, but human activity is accelerating this. 

Evidence for climate change can come from tree ring analysis, ice core samples, and observations of changes in ice cover.

A key control of the climate is the amount of 'Greenhouse Gases' that are present, including:-

• Carbon dioxide

• Methane

• Nitrous oxide

These gases act 'like a blanket' trapping heat within the Earth's atmosphere:-

As previously discussed, the Earth's natural greenhouse effect has caused the Earth's temeprature to be higher than what it would otherwise be, allowing life to exist. However, human activity has increased its effect dramatically.

Since the industrial revolution on the mid-19th century human emitting large quantities of greenhouse gases into the air through the burning of Fossil Fuels for energy and transportation, human activity has greatly enhanced the natural level of the greenhouse effect. The graph below shows how the average global temperature has changed since the 1880's. As can be seen, the average temperature shows a clear trend of increasing since this time:-

If the carbon dioxide concentration is overlaid on this data, the following close correlation can be seen:-

The consensus of the scientific community is that this increase in carbon dioxide level is directly responsible for this temperature increase, that human activity is changing the global climate. 

There is evidence that this increase in carbon dioxide is definitely due to human activity. The graph below shows the changes in carbon dioxide concentration over the last 800,000 years. As can be seen, the large spike in carbon dioxide concentration is completely beyond the natural variation levels, and so is extremely likely to be Human caused:-

Sources of Greenhouse Gases

The greenhouse gases that are emitted by human actions come from a wide range of activities, the main five actions being:-

• Burning fossil fuels for heat and electricity.

• Fossil fuel use in transport.

• Agriculture.

• Deforestation.

• Cement manufacture.

The impacts of Climate Change

Climate change is not a s simple as everywhere getting warmer, the effects are different for different areas. Some areas will experience increased temperatures, decreases in rainfall or changes in precipitation (for example snow to rain), while others will get higher levels of rainfall or more extreme changes in seasonal temperatures. 

Other changes that can be seen include:-

• More frequent and intense weather events, such as Hurricanes and Cyclones.

• Changes to major weather systems like Monsoon and El Niño, strengthening in some areas, reducing in others.

• Climate bands moving further north or south (depending on hemisphere), changing what plants or animals can survive in a particular location. 

• Flooding of low lying land due to sea-level rises.

• The spread of tropical diseases further north or south, such as malaria, as the carriers follow the climate bands. 

• The melting of glaciers causing flooding and more water scarcity for communities downstream.  

The video below shows the effects of up to 3 degrees of further warming on the global climate:-

Mitigation of Climate Change : Global Policy

The damage that the emission of greenhouse gases  has done the the climate will continue as long as the gases are present, but the global society is beginning to work together to at least prevent the situation from getting much worse. 

In 2021, leaders and policy makers from countries across the globe met in Glasgow for the 26th UN Climate Change Conference of the Parties (COP26). The outcome of this conference was that almost 200 countries, both MEDCs and LEDCs, committed to keeping the human enhanced warming below 2°C above the pre-industrial levels, and with commitments to further action over the next decade, to aim to keep it below 1.5°C. This commitment is known as the Glasgow Climate Pact. 

The video below shows a short summary of the outcomes of COP26:-

Mitigation of Climate Change : Industry, Transport & Agriculture 

In order for national governments to implement the Glasgow Climate Pact, changes need to be made in every aspect of life, so that energy use is more sustainable and emission of greenhouse gases are reduced:- 

Mitigation of Climate Change : Personal Changes 

The diagram below shows some methods for saving energy, and the average value of money saved by these methods:-

Commercial energy assessors test how energy-efficient commercial buildings are – like shopping centres, cinemas and offices. They create Non-Domestic Energy Performance Certificates that can recommend how businesses can be more energy efficient. This can make a big difference to the environment around us and make sure the public are safe while out and about. 

A domestic energy assessor is qualified to assess the energy efficiency of residential properties like houses and flats. You’ll be keeping families safe by checking that their energy systems are up to the right standards. And you’ll be making a difference to the environment.They prepare reports and make recommendations for cost effective ways to improve energy performance in buildings. These reports are called Energy Performance Certificates (EPCs) and are carried out during the buying and selling of residential homes.  

Energy Sources

Energy is vital for every process in the universe to occur and is used by transferring it from one energy store to another. Systems that can store large amounts of energy are called energy resources. As previously stated, switching to a renewable source of Energy is a key method for reducing 'greenhouse gas' emission and reducing the effects of Climate Change. 

The major energy resources available to produce electricity are:-

• Fossil Fuels (Coal/Oil/Natural Gas).

• Nuclear Power.

• Hydroelectric Power.

• Wind Power.

• Solar Power.

• Wave Power.

• Tidal Power.

• Geothermal Power.

At present, the vast majority of energy use globally is provided by Fossil Fuels:-

The Top 5 energy consuming countries (apart from Iceland) rely almost exclusively on Fossil Fuels for thier enery production : 

Fossil Fuels

The main source of Energy since the Industrial Revolution has be the fossil fuels - Coal, Oil and Natural Gas. These are the remains of living organisms that died millions of years ago which were buried and the subject to huge Temperature and Pressure. The diagrams below show how the three fossil fuels were formed:-

Thermal Power Stations

All three fossil fuels generate Electricity in the same way, by acting as essentially a large kettle. The fuel is used to heat water, with the resulting steam being used to drive a turbine, which in turn drives a generator, generating Electricity. 

The diagram below shows a simplified cross-section of a thermal power station:-

The energy changes in a thermal power station are:-

1. Burning the Fuel - Chemical Energy converted to Heat Energy.

2. Steam driven Turbine - Heat Energy converted to Kinetic Energy.

3. Generator - Kinetic Energy converted to Electrical Energy.

The video below  (first 10 minutes only) shows a detailed explanation of how a Coal-Fired Power Station functions, as well as some ways that carbon dioxide emissions can be reduced:-

Hydroelectric Power

Hydroelectric power uses the Energy of water flowing rapidly downhill to generate Electricity. The diagram below shows a simplified cross-section of a Hydroelectric Power Station:-

As the water is at a high point above the dam, the water contains Gravitational Potential Energy.  As the water flows down the penstock (tunnel through the dam), the Gravitational Potential Energy is converted to Kinetic Energy. This Kinetic Energy is used to turn a turbine and drive a generator, which generates Electricity. 

The energy changes in a Hydroelectric Power Station are:-

1. Stored in Loch behind Dam - Gravitational Potential Energy.

2. Water flowing downhill - Gravitational Potential Energy converted to Kinetic Energy.

3. Turbine and Generator - Kinetic Energy converted to Electrical Energy.

Wind Power

Wind power uses the Energy of moving air to generate Electricity. The diagram below shows a simplified cross-section of a wind turbine:-

When the wind blows, the moving air causes the blades of the wind turbine to rotate. These rotating blades are attached to a shaft which drives a Generator, generating Electricity. 

The energy changes in a Wind Turbine are:-

1. Moving Air (Wind)  - Kinetic Energy.

2. Turbine and generator - Kinetic Energy converted to Electrical Energy.

Solar Power

There are two main ways to generate Electricity using the Energy from the Sun. 

These are:-

1. Photovoltaic Cells (Solar Cells).

2. Solar Thermal Power Stations.

Photo-voltaic Cells 

Photovoltaic Cells (more commonly known as Solar Cells) convert light energy directly into Electricity. The process of how this happens is covered in the Higher Physics course. The diagram below shows a simplified cross-section of a Photovoltaic Cell:-

The energy changes in a Photovoltaic Cell are:-

1. Sunlight - Light Energy.

2. Photovoltaic Cell - Light Energy converted to Electrical Energy.

Solar Thermal Power Station

A Solar Thermal Power Station uses focused sunlight to generate Electricity. The diagram below shows a simplified diagram of a Solar Thermal Power Station:-

A Solar Thermal Power Station uses Focussed Sunlight to boil water into Steam. This Steam is then used to drive a Turbine and Generator in the same way that a Fossil Fuel Power Station does. 

The energy changes in a Solar Thermal Power Station are :-

1. Sunlight -  Heat Energy.

2. Steam driven turbine - Heat Energy converted to Kinetic Energy.

3. Generator - Kinetic Energy converted to Electrical Energy.

Wave Power

A Wave power generator uses the motion of waves to generate Electricity. This motion is used to drive a hydraulic generator, which generates Electricity. The diagram below shows a simplified diagram of a prototype wave power generator:-

n the above system, the yellow section of the device float on the water's surface. As the waves pass, the device opens and closes, forcing sea water into the flow line. This drives either a hydraulic pump or a Hydroelectric system on the land, which generates Electricity. 

The energy changes in a Wave Power Generator are:-

1. Waves- Kinetic Energy.

2. Hydroelectric Generator - Kinetic Energy converted to Electrical Energy.

The video below shows an animation of how the above wave power generator functions:-

Tidal Turbine

A Tidal Turbine uses the Energy of water flowing in tides to generate Electricity. The diagram below shows a simplified diagram of a tidal turbine:-

The Tidal Turbine works in a very similar way to a wind turbine, with the motion of the water causing the blades of the wind turbine to rotate. These rotating blades are attached to a shaft which drives a generator, generating Electricity. 

The energy changes in a tidal turbine are:-

1. Moving water (tides)  - Kinetic Energy.

2. Turbine and Generator - Kinetic Energy converted to Electrical Energy.

Geothermal Power

Geothermal power uses the heat Energy contained within hot rocks deep underground to generate Electricity. The diagram below shows a simplified diagram of a Geothermal power station:-

A Geothermal power station uses heat from deep underground to boil water into steam. This steam is then used to drive a turbine and generator in the same way that a fossil fuel power station does. 

The energy changes in a Geothermal power station are:-

1. Geothermal Rocks -  Heat Energy.

2. Steam driven Turbine - Heat Energy converted to Kinetic Energy.

3. Generator - Kinetic Energy converted to Electrical Energy.

Future Energy Production

The video below shows some novel types of Electricity generation, some in use commercially now, others that are only in the prototype stage:-

Impacts of Climate Change : The Living Environment

‘Climate Change’ is having a massive impact on the living environment. 

Climate change affects the living environment in 3 key ways : 

• Habitat Loss

• Reduction in Biodiversity 

• Changes in Species distrubution 

Due to warming global temperatures, many species are being displaced further North or South, seeking cooler temperatures : 

This has a large impact as not all species are displaced at the same rate, risking the collapse of food webs when food sources are lost . 

For example, the maps below show the mismatch between a Butterfly and its host plants, caused by climate change : 

Species are also moving to higher elevations where possible, again seeking cooler temperatures. Unfortunately, this has lead to loss of species at the highest elevations, as they have no where further to go :

Changes in species distribution Case Study : The Bobolink

For Further Data from the National Audubon Society showing the changes in the bird ranges of North America due to Climate Change (including to temperatures above 1.5°C), please follow this link. 

Impacts of Climate Change : The Physical Environment

Climate Change not only has an effect on living organisms, but on the Phyiscal Environment as well. The rising temperature is leading to the loss of snow and ice cover globally : 

This loss of snow and ice cover can be clearly seen in the loss of Sea Ice in the Arctic Ocean : 

As well as in Glaciers around the World : 

This loss of snow and ice cover has impacts on local biodiversity as well as impacts on water supplies for communities downriver of the glaciers : 

Due to warming temperatures, sea levels have also begun to rise around the World : 

The rising water level is partly due to melt water from glaciers and ice sheets, but the largest contributer is the thermal expansion of seawater as it warms : 

As water temperature increases, the molecules that make up the water will vibrate more, causing the volume of a fixed mass of water to increase, reducing its density : 

This means that the even without meltwater entering the Oceans, the ocean level would rise with increasing temperature as the water that is already there will occupy a large volume. 

The following diagram shows how the sea level is predicted to rise over the next 60-80 years, depending on Greenhouse gas emission rates : 

Climate Change also can cause the loss of productive farmland through a variety of ways : 

• Loss of land through increased coastal erosion

• Loss of land due to salt water intrusion

• Desertification due to changes in weather patterns

The Economic Cost of Climate Change

Climate Change has a global economic cost via;  agricultural yields, the physical and cognitive performance of workers, demand for energy, disaster management, as well as increasing the incidence of crime, unrest, and conflicts.

The graph below shows how the costs of extreme weather events globally has increased since 1980 : 

As seen previously, the impact of climate change is not shared equally. LEDCs are more likely to be in regions exposed to the greatest impacts of climate change and also do not have the finacial capabilities to adapt rapidly enough to the changing climate :