Get Energised! Secondary Teachers’ Guide
Total Page:16
File Type:pdf, Size:1020Kb
Get Energised! Secondary Teachers’ Guide 2017–18 Get Energised! Curriculum links Get Energised! Topic Curriculum links Nat 3 – Energy sources, Electricity Teachers’ Guide Hydroelectric Power Nat 4 – Generation of electricity The purpose of this guide is to provide scientific information on the different sectors of renewable Nat 5 – Conservation of energy, Electrical power energy in Scotland. This can be used as a starting point for activities and further discussion with pupils on how we use renewable energy in real life. Nat 3 – Electricity, Solar system Solar Power Nat 4 – Generation of electricity, Cosmology Nat 5 – Conservation of energy, Electrical power Contents Nat 3 – Energy sources, Electricity, Solar System Wind Power Nat 4 – Generation of electricity Get Energised! Curriculum links 1 Nat 5 – Conservation of energy, Electrical power Renewable Energy in Scotland 1 Nat 3 – Energy sources, Electricity, Solar System Hydroelectric Power 4 Marine Power Nat 4 – Generation of electricity Nat 5 – Conservation of energy, Electrical power Solar Power 7 Wind Power 11 Renewable Energy in Scotland Marine Power 15 The Scottish government has a target of generating 100% of Scotland’s electricity Discussion Activity 19 demand from renewable sources by the year 2020. Scotland generates more electricity Further Sources 21 than it uses and just over a quarter of the energy produced was exported. Renewable electricity is generated from sources such as wind, tides, waves and sunlight. Unlike fossil fuels, these are sources which will not be depleted if we use them to generate electricity. For more information about our free Get Energised sessions, visit www.nms.ac.uk/GetEnergised The amount of electricity used in Scotland that has come from a renewable source has grown You can also contact us on [email protected] over the past several years. This can be seen in the following chart: 60 57% 54% 49.9% 50 44.5% 39% 40 36.2% 30 23.9% 20 10 0 2010 2011 2012 2013 2014 2015 2016 Percentage of electricity used that comes from renewable sources In addition to the electricity target, the Scottish Government are holding a consultation on the proposal that 50% of all Scotland’s energy should come from renewable sources by 2030. This includes transport and heating. There are a large number of jobs within the renewable energy sectors in Scotland. The latest figures show that over 20,000 people are employed across areas such as wind, solar and hydro power. The roles will be a mixture of research, development and engineering jobs. These will be supported by positions in marketing, human resources and accountancy. Horizontal axis wind turbine 1 The National Grid Non-renewable source: The electricity generated by these renewable sources is moved to where it is needed on the Installed Capacity (2016) National Grid. It connects the places that generate electricity (e.g. hydroelectric power stations, Item World-wide (WW) Source of loss Type of loss Efficiency wind farms) to homes and businesses. In recent years individuals and communities have been Scotland (S) generating their own electricity from items such as solar panels or wind turbines. These are also connected to the Grid and people can earn money for the electricity they don’t use. Waste heat is produced as part Coal fired 20000 GW (WW) of the process and is released Heat 33% In order to move electricity to where it is needed, the voltage is power station 0 GW (S)* into a cooling tower or is used to heat nearby buildings increased from around 1-30 kilo Volts to hundreds of kilo Volts. It is then stepped back down again for use when it reaches its destination. Like a coal fired power station, Nuclear 345 GW (WW) not all heat can be used to By increasing the voltage, the losses due to resistance are limited. Heat 40% power station 26 GW (S) produce electricity and some is released Measuring Output *The last coal power station in Scotland, Longannet, closed in 2016. When running its capacity was 24GW. The output of power stations and individual items such as solar panels and wind turbines can be Renewable source: measured in terms of energy or power: Installed Capacity (2016) • A measure of energy commonly used by companies to make a charge for electricity use is Item World-wide (WW) Source of loss Type of loss Efficiency 6 kilo Watt hours, kWh. One unit of energy is 1 kWh = 3.6 Megajoules = 3.6 x 10 Joules. Scotland (S) • The power for a wind farm or power station can be listed in terms of kiloWatts, kW (1000 W), Heat and noise of mechanical MegaWatts, MW (1,000 kW) or GigaWatts, GW (1000 MW). For example, Whitelee Wind 486 GW (WW) parts, wind is not constant so Heat Wind Farm 30% Farm near Glasgow has a capacity of 539 MW and is one of the largest in Europe with over 9.3 GW (S) amount of electricity generated Noise 200 turbines. varies Due to their design and The capacity is the maximum potential power of the type of technology used for electricity Type of construction, panels cannot generation. 302 GW (WW) material Solar power produce electricity from all 22% 328 MW (S) (size of wavelengths of light falling on • When the capacity for a site is discussed it is important to remember that the actual power band gap) and energy produced could be lower than the capacity due to varying local conditions. it, e.g. ultraviolet or infrared Heat and noise of mechanical • For example, wind turbines will not be operating at their maximum 24 hours a day. Their parts. Efficiency is higher than operation will depend on the wind speed each day. Average wind speeds can also vary from Hydroelectric 1064 GW (WW) Heat wind, for example, due to the 80-90% power 1.6 GW (S) Noise year to year. consistent source of water to turn the turbines Efficiency 0.5 GW (WW) Heat and noise of mechanical Heat Depends on When electricity is generated, the process is not 100% efficient. For example, not all of the kinetic Marine power energy in the wind is converted to electricity by the wind turbine. Energy is lost through friction, 13 MW (S) parts Noise technology heat and noise as the mechanical components in the wind turbine move. The National Grid: P out Efficiency (%) = ×100 P in Item Source of loss Type of loss Efficiency The loss is due to the resistance of the Electricity An estimate of efficiencies for different types of electricity generation can be found below. The cable. The resistance depends on the transmission Heat 95% distance the electricity is transferred efficiency level can vary between sites using the same type of generation. For example, a newer line wind farm will have better technology than an older site. and the current The following sections explore four different sectors of renewable electricity generation. 2 3 Hydroelectric Power In general, there are two different kinds of turbines: impulse and reaction. Hydroelectric power is in widespread use in Scotland because of the natural geography of the land. There is one large-scale site in Wales but none in England. • In order to generate electricity, water is dropped from a height to drive turbines. Impulse: It has gravitational potential energy and gravity then pulls the water down when the flow is released. • The kinetic energy of the water is transferred into mechanical energy in the turbine. • The result is the generation of electricity as the turbine drives a generator. • It is a very efficient process, with 80-90% of the energy from the moving water being used to generate electricity. High-level reservoir An impulse turbine • The blades of an impulse turbine are driven by a water jet. • The water flow is concentrated through a nozzle, which is then fired at the blades and the Height pressure from the water is constant. Newton’s second law can be called on to describe the behaviour of this turbine. Water flow • This type of turbine is generally used when there is a high head of over 300 m. Turbines and electrical generators Reaction: Low-level loch Hydroelectric power station Turbines Hydroelectric power stations can be described based on the value of their height or “head”. This is a measure of the distance between where the water is stored and where it will end up A Reaction turbine once it has passed the turbines. • To generate electricity, the water flow is controlled on its way to the turbines. • A reaction turbine has to be fully sealed as the water flows through the turbine, causing the blades to spin. • The choice of turbine does not depend on the water flow but on the head of the site. • The operation of this turbine falls under Newton’s third law: for every action there is an • There are more than 80 hydroelectric power stations in Scotland, all with different values equal and opposite reaction. for the head and in them are many generations of turbine technology. • In cases where the head is classed as being low or medium (up to 300 m) the reaction turbine tends to be used. 4 5 Types of power stations Solar Power There are different kinds of hydroelectric power stations. Each of the following methods is used The Sun is our ultimate source of energy on Earth and as such we want to harness as much to generate electricity in Scotland: of its power as possible. The Sun can provide us with a huge amount of power to generate 1. Pumped storage (Cruachan Dam at Loch Awe and Foyers at Loch Ness in the Highlands electricity with.