Energy and Environment - Grade 8 File Note - PDF

Merryland International School Environmental management- Grade-8 Chapter -2; Energy and the environment – File note 2.1 Non-renewable Energy Sources o Non-renewable energy comes from energy sources that will eventually run...

Merryland International School Environmental management- Grade-8 Chapter -2; Energy and the environment – File note 2.1 Non-renewable Energy Sources o Non-renewable energy comes from energy sources that will eventually run out, including: o Fossil fuels o Nuclear energy (using uranium as a fuel) What Are Fossil Fuels? Fossil fuel is a carbon-based fuel, formed under heat and pressure over millions of years from the decay of living matter  Fossil fuels include: o Coal o Natural gas (mostly methane) which is used in domestic boilers and cookers o Crude oil, which is refined into petrol, diesel and other fuels  Fossil fuels are formed from the remains of plants and animals: o Chemical energy stored in fossil fuels originally came from sunlight o Energy from the sun was transferred to chemical energy stores within plants through photosynthesis (plants use energy from sunlight to make food) o Animals ate the plants and the energy was then transferred to their chemical store How are fossil fuels formed? o Fossil Fuels are formed from the dead remains of plants and animals which are buried in earth crust and compressed by heat and pressure over many millions of years  Oil and natural gas were mainly formed from dead marine organisms 1 How is coal formed? As the plants died, they sank to the bottom of the swamps. Over the years, thick layers of plants were covered by dirt and water. They were packed down by the weight of the sediments. After a long time, the heat and pressure changed the plants into coal. How is natural gas and oil formed? o Natural gas and oil is formed from sea creatures o Small marine animals and plants die and fall to the bottom of the sea. o Their remains are covered by sediments o The heat and pressure turn the remains into crude oil and natural gas o The rock above the oil and gas is nonporous o So they get trapped underneath it. Advantages  The current systems of transport and electricity generation used by human societies rely heavily on fossil fuels, which are generally readily available on a daily basis  In the past fossil fuels have been reliable for large-scale energy production (although this is changing as supplies deplete and prices rise)  Efficient - fossil fuels typically have a high energy density (they produce a large amount of energy per kilogram) Disadvantages  It takes millions of years for fossil fuels to form:  This is why they are considered to be a non-renewable energy resource 2  The increasing demand for a decreasing supply causes prices to increase:  Fossil fuels are predicted to completely run out within the next 200 years  Burning fossil fuels pollutes the atmosphere with harmful gases such as:  Carbon dioxide, which contributes to the greenhouse effect, Sulphur dioxide, which produces acid rain  Both carbon and sulphur can be captured upon burning, preventing them from being released into the atmosphere, but this is expensive to do  Oil spills can occur during transport of fossil fuels, which damage the environment and wildlife over very large areas  Prices fluctuate rapidly  Supplies can be affected by conflict and political disagreements (e.g. the war in Ukraine) Primary global energy consumption Uses of Fossil Fuels  Fossil fuels are mainly used for:  Transport  Generating electricity  Heating  Transport  The majority of vehicles in the world are powered by petroleum products such as petrol, diesel and kerosene: These resources all originate from crude oil, which is a fossil fuel  A growing number of vehicles are now being powered by electricity: The advantage of this is that while the vehicle is being driven, it produces zero carbon emissions 3  The disadvantage is that when the vehicle is being charged, it is connected to the National Grid, which currently uses a combination of renewable and non- renewable energy sources  Electricity generation Fossil fuels, such as coal and oil, are used to produce energy on-demand when energy is needed:  This is done by burning the materials when the energy is required o When coal is burned, it produces heat (thermal) energy o This is used to boil water creating steam o Steam is forced around the system and this turns a turbine o The turbine turns coils in a magnetic field in the generator: o This generates electricity o The electricity is transferred through a step-up transformer and is carried out of the system by electrical lines o The steam within the turbine will cool and condense and then be pumped back into the boiler to repeat the process Energy Demand  The demand for energy across the globe is rising o Population growth and development are the two main causes of the increase in energy demand: o The higher demand for food leads to more intensive farming, which requires more energy for machines, light and heat o Increasing industry requires energy for heating, lighting and machinery o There is more transport, all of which requires energy in the form of petrol, diesel or electricity o Urbanisation increases with the development increasing domestic appliances, heating and lighting 4  o Increased wealth (economic growth)means people buy more appliances and technology, which require energy Nuclear Energy  Energy stored in the nucleus of atoms (uranium)can be released when the nucleus is broken in two: o This is known as nuclear fission  Nuclear power stations use fission reactions uranium atom to create steam to turn turbines to generate electricity  Nuclear power is a low carbon, low-emission, non-renewable resource but is controversial due to the radioactive waste it produces and the potential scale of any accident Advantages  No pollution released into atmosphere  Nuclear reactors are perfectly safe as long as they are functioning properly (rigorous safety checks must be routinely carried out and rigorous safety procedures followed)  Nuclear power stations can generate electricity reliably on a large scale to be available as needed  Small amounts of uranium are needed, and large reserves are available  Reduces reliance on fossil fuels  Increases energy security 5  Disadvantages  Uranium ore found in the ground is used for fission reactions and since there is a finite supply, nuclear power is a non-renewable resource  Nuclear fuels produce radioactive waste, which needs to be stored for thousands of years Safe ways of storing radioactive waste are very expensive  If an accident occurs at a nuclear reactor, radioactive waste can leak out and spread over large areas Cost of decommissioning (shutting down) nuclear power plants is very high Nuclear energy is often used in countries that do not have their own supplies of fossil fuels, such as France In 2019 approximately 4% of the global primary energy supply was from nuclear power There are 439 active nuclear reactors across the world. Most of these are in just five countries: USA (92) ,France (56), China (54). Russia (37), Japan (33) Renewable Energy Sources What Are Renewable Energy Sources?  Renewable energy comes from energy sources that will not run out and includes: o Biofuels (biomass including wood, bioethanol and biogas) o Geothermal energy o Hydroelectric dams o Tidal energy 6  o Wave energy o Solar energy o Wind energy  Once in place, these renewable energy sources do not produce any greenhouse gas emissions (with the exception of biomass): o However, it is important to note that greenhouse gases may be emitted in the production, construction and transport of the equipment required for the above renewable energy sources Renewable Energy Sources Examples Biofuels  Biofuels (also known as biomass fuels) are renewable fuels derived from organic materials, such as plants and animal waste, that can be used as an alternative to fossil fuels: o However, they have only half the energy density of fossil fuels  The three main biofuels are: o Biodiesel - made by refining renewable fats and oils (e.g. vegetable oils, animal fats or recycled cooking oil) o Bioethanol - made by fermentation (of crops rich in sugars or starches, such as corn or sugarcane) o Biogas - released when organic waste products decompose Advantages  Biofuel is a renewable resource - uses waste or bio products that can be regrown  Some vehicles can be powered by biofuel rather than using fossil fuels  Biofuel is considered to be carbon neutral  No sulfur dioxide is produced Disadvantages  Crops of biofuel producing plants must be grown, which takes time 7   Growing the crops takes a lot of land, and takes resources needed for food production  Burning biofuels releases carbon dioxide into the atmosphere (however, it is considered carbon neutral because plants take in carbon dioxide when they photosynthesise) Geothermal Energy  Geothermal energy is caused by the heat that is generated from within the Earth: o The Earth's interior is extremely hot, partly due to radioactive elements deep in the Earth that release energy as they decay  This geothermal energy heats up rocks in the Earth's crust, sometimes to an extremely high temperature: o Water can be poured into shafts below the Earth's surface o The water is heated and returned via another shaft as steam or hot water o Steam can be used to turn a turbine and generate electricity, and the hot water can also be used to heat homes Advantages  Renewable resource  Reliable source of energy  Geothermal power stations are usually small compared to nuclear or fossil fuel power stations Disadvantages  Few suitable locations on Earth, so only viable for small scale electricity production in many countries 8   Can result in the release of greenhouse gases from underground  Expensive to build and maintain Hydroelectric Dams  When water is stored above ground level it has gravitational potential energy  This energy can be transferred to kinetic energy if the water is allowed to flow down the slope  Flowing water turns the turbine to generate electricity Advantages  Can respond to demand quickly so is reliable and available  Can generate large-scale amounts of electricity in a short period of time  Often in sparsely populated areas Disadvantages  Expensive to build and maintain  Creating reservoirs sometimes results in the need to flood valleys, which destroys habitats, towns and villages  The pumping systems (used if water needs to be pumped up to the reservoir) often rely on fossil fuels, releasing large amounts of greenhouse gases  Dam traps sediment which can affect ecosystems downstream  Visual pollution  Can prevent fish movement and migration upstream 9 Wave & Tidal Energy  The rise and fall of waves or the tide can be used to turn a turbine and generate electricity Tidal power Wave power Advantages  No pollution  Reliable and can produce a large amount of electricity at short notice  Renewable energy resource  Small systems are being developed to provide electricity for small islands Disadvantages  Expensive to build and maintain  Damages fragile habitats  Very few suitable locations  The technology is not advanced enough for large-scale electricity production 10 Solar Energy Uses photovoltaic cells that produce a small electric charge when exposed to sunlight. A bank of cells organized into solar panels produce a significant amount of electricity. Advantages o Solar energy is a renewable resource o In many places on Earth sunlight is a reliable energy resource (this means that the sun shines most of the time) o Solar farms produce no greenhouse gases or pollution o Solar energy can be generated in remote places where they don't have electricity (e.g. to power solar street signs in rural areas) o Can be small- or large-scale o Can be incorporated into building design o Technology is improving and reducing the cost Disadvantages o Solar farms need to be large-scale to produce large amounts of electricity, which is expensive to set up o Uses large areas of land o People often don't like the appearance of large solar farms; this is known as visual pollution o In many places on Earth sunlight is not a reliable energy resource (there are not enough sunshine-hours to justify the set-up costs) Wind Energy  Wind energy is a renewable form of energy that harnesses the power of the wind to generate electricity  It involves the use of wind turbines, which have large blades that spin when the wind blows  The rotating blades transfer kinetic energy to a generator, which converts it into electrical energy Advantages  Wind is an abundant resource that will never run out, making wind energy a sustainable and renewable source of power 11   Wind energy produces no greenhouse gas emissions or air pollutants during operation, helping to reduce the negative impact on climate change and air quality  Wind energy reduces dependence on fossil fuels and foreign energy sources, promoting energy independence and security  The wind energy industry creates jobs in manufacturing, installation, operation and maintenance of wind turbines  Can be small- or large-scale  Can be on land or offshore  Cheap to run Disadvantages  Wind is not constant, and the availability of wind energy fluctuates  Electricity generation from wind turbines depends on wind speed and consistency  Wind turbines can be visually intrusive, especially when installed in large numbers  Some people may find the noise generated by wind turbines to be disruptive  Wind farms require large areas of land, which can have an impact on agricultural or natural landscapes  Birds and bats may occasionally collide with wind turbines, causing some impact on local wildlife populations 12