Early History of Energy Use
The primary source of energy on the Earth is solar radiation from the Sun which sustains all life. The energy falling on the Earth varies around the globe resulting in a strong correlation between the volume of living matter (biomass) and mean sunlight. At higher latitudes where there is less sunlight, there are generally fewer living creatures.
However, human beings are not completely constrained by the availability of solar energy because of their capacity to alter the environment to make it more suitable for life (Fig. 1). Light and heat can be artificially generated by burning organic materials; naturally available materials can be used to construct shelter and provide thermal insulation in the form of clothing; animals can be confined and used to do work; new materials such as metals and alloys with useful properties can be synthesised from raw materials. These are examples of how natural resources were used to support life in early history. Increasing technological development permitted other sources of energy to be exploited. Wind power played an important part in the development of human civilisation and was thought to have been first harnessed using sail boats about 5,000 years ago. The ability to move easily through the oceans allowed the rapid dispersal of people to all regions of the world. Windmills were used to mill grain and pump water and were introduced about the same time. The Dutch used windmills extensively from the 14th century for drainage and land reclamation (Fig. 2). The basic technology remains very similar to that of wind turbines we would use today to generate electricity.
Figure 1: The ultimate expression of the freedom of human beings to escape environmental constraints is the ability to leave the Earth and travel through space.
Figure 2: An early Dutch windmill. A study of windmills in art shows how windmills developed from the 12th to the 20th century.
Energy can also be extracted from the movement of water. Wave and tidal power were not generally utilised in the past, but the water flow through rivers and streams is easier to exploit. One cubic metre of water weighs one tonne, and this weight of water falling with gravity can do a significant amount of work. The conventional way of capturing the energy was by fitting a waterwheel on a river with paddles turned by the weight of the falling water or the kinetic energy of the flowing water. The mechanical energy could then be used to do useful work.
The principle was extended and controlled in the 19th century with the development of hydroelectric schemes. A dam is used to stop the natural flow; the water builds up behind the dam acquiring potential energy; water is released through a turbine to generate electricity when required.
Geothermal energy was also used as a heat source. But there are vast natural sources of energy that cannot, even with current technology, be exploited—these include hurricanes, earthquakes, and volcanic eruptions.
Activity 1
Please note – internet access is needed for this activity. If this is not possible, do not worry, it is for interest only.
The quantity of solar radiation incident on one metre square area of the surface of the Earth depends on the month of the year and the latitude.
Using https://power.larc.nasa.gov/data-access-viewer/ Find the latitude and longitude coordinates of the place where you live, get the total amount of energy incident on 1 m2 of surface area at your location for each month of the year. Produce a graph of the monthly variation using Excel. Calculate the total energy for the year. On average, how many Joules is incident on 1 m2 of surface each second. How does this compare with the theoretical 342 W m-2 incident on the outer atmosphere at the equator?
Solution:
The stages in obtaining and processing the data are shown below. First visit
https://power.larc.nasa.gov/data-access-viewer/,
Once found follow orders.
- Select SSE-Renewable Energy
- Select Climatology
- Select Point and select area in which you are evaluating or type coordinates.
- Ignore Date as this is preselected with a yearly historic average value.
- You can output the data if preferred but it is not necessary
- Select Tilted Solar Panels for Solar Irradiance.
- Submit the request
Once submitted, the unit value for the month can be view by hovering over the graph. Alternatively, you can output the data to excel.
Submitted data for LCC (Lews Castle College) is shown below, excel chart on the left and related graph on the right.
|
Units per Square Metre Per Day |
Days |
Units pM |
|
|
Jan |
0.36 |
31 |
11.16 |
|
Feb |
1 |
28 |
28 |
|
Mar |
2.09 |
31 |
64.79 |
|
Apr |
3.65 |
30 |
109.5 |
|
May |
5.03 |
31 |
155.93 |
|
Jun |
5.11 |
30 |
153.3 |
|
Jul |
4.65 |
31 |
144.15 |
|
Aug |
3.96 |
31 |
122.76 |
|
Sep |
2.63 |
30 |
78.9 |
|
Oct |
1.35 |
31 |
41.85 |
|
Nov |
0.53 |
30 |
15.9 |
|
Dec |
0.24 |
31 |
7.44 |
|
Total Annual Units |
933.68 |
||
|
Total Annual Joules |
3.36E+09 |
||
|
Watts Per Square Metre |
106.58 |
||
Once the information is typed into Excel, you should realise the data (B2:B13) is expressed as Units of Electricity per day. To find the monthly total Units, we need to insert a new column (C2:C13) listing the number of days in the corresponding month. The monthly total is then calculated in the next column by entering = B2*C2 into D2 then filling down to D13. The annual total is calculated in D14 using the formula =SUM(D2:D13). Multiply by 3,600,000 to convert to J by entering =D14*3600000 into cell D15. Note that E+09 is the same as x 109. Finally, work out the mean Watts per square metre (not metre squared) at your location by dividing by the number of seconds in a year. The formula is =D15/31536000 and should be entered into cell D16. [CONTACT THE TUTOR IF YOU ARE NOT COMFORTABLE USING EXCEL]
The value is 106.58 W m-2. This is much smaller than the expected value of 342 W m-2 because the ground is at an angle with respect to the Sun’s rays, with the result that light is spread over a greater area (see the diagram below right). If you have time, do the same calculation for a point on the equator (latitude = 0 , longitude = 0 ). The value you will find is much greater that the one previously calculated, but why is it not 342 Wm-2? Because the atmosphere reflects and absorbs some of the radiation.
The low mean energy at higher latitudes (mirrored below the equator) has important implications for the siting of renewable energy systems that exploit solar radiation (as we will see later). 101.7 W m-2 is about the heat produced by a 100 W filament light bulb falling on that area. For the mathematically minded, the energy drops by a factor approximately equal to the cosine of the latitude.
Figure 3 - Demonstration of variation of area as latitude changes. Drawn by Owen Inger - Gray of LCC
The Industrial Revolution
The invention of the steam engine heralded the beginning of the industrial revolution (Fig. 3). Machines were produced to take over many manual tasks leading to standardised mass production. Increasing iron production and the development of roads, bridges and railways to move products and raw materials allowed industrialisation to spread and grow rapidly.
But the machines needed energy, a huge amount of energy, and the energy source at the time was coal.
Coal is plentiful and cheap and Fig. 4 shows the enormous increase in production in the UK over the course of the 19th century and early 20th century, giving rise to the soot and grime that were characteristic of that age.
Figure 4: James Watt developed the first effective steam engine between 1761 and 1769. Coal is used to boil water and the energy of the condensing steam is converted to mechanical work.
Source figures used under fair dealing.
Figure 5: The first chart shows the world coal consumption divided into subgroups and how many involvements it has within the world today. Future world coal production is expected to follow the second graph. As developing nations follow the same path as a response to the increasing cost of oil and gas.
With the development of the petrol and diesel engines in the late 19th century, the more convenient oil became the fuel of choice and almost all machinery was converted to run off oil. Virtually the only remaining uses for coal was home heating and for electricity generation as distribution networks were set up to make power available in the home.
The consumption of oil increased dramatically over the 20th century, with the growth of transportation. The motor car represented individual freedom and once production was mechanised and mass produced on assembly lines by Henry Ford from 1908, the car became affordable, and millions were manufactured and sold
But a car is hardly an efficient method of travelling - the machinery is so elaborate that to convey a single person weighing 100 kg, it is necessary to move machinery weighing 1,000 kg (1 tonne). Energy is used fighting the contact frictional force and air resistance.
Aeroplanes (airplanes - U.S.) represented complete freedom and commercial flights ‘took off’ from the 1950’s. Air travel is even less efficient because an aeroplane works against gravity while ascending to cruising altitude. Fuel consumption increases as a result. Consideration of transport efficiency should be a factor in choosing a mode of transport.
There is evidence that energy consumption in the US and Europe is now levelling off as we enter the age of communication. The increased freedom (the Internet and moving from fixed to mobile phones) is equally dramatic but is not associated with a huge increase in energy use.
Industrialisation started in the late 18th century in Britain and still continues today. Some economically more developed regions of the world have achieved a higher degree of industrialisation and consequently have a higher standard of living. Economically less developed nations such as some countries in Africa and India, lag behind, but aspire to the level of affluence of the developed countries. It is unreasonable to deprive citizens of developing countries of the right to strive for a higher standard of living (regardless of negative arguments concerning wealth), and this is recognised in climate change agreements such as the Paris agreement (examined later in the course). As a country progresses along the path of increasing industrialisation, more and more energy is required to sustain development, and, as we will see, this makes it difficult to predict future global energy consumption.
Activity 2
Produce a table of the fuel efficiencies associated with different modes of transportation gathering information from any sources available to you, such as books, magazines, or the internet. If the information from different sources do not agree, what value should you choose?
The table below summarises the information from various web sites. Searching on ‘fuel efficiency per passenger” will bring up more sites. What about motorcycles? If there is any difference, ask yourself if any site is trying to present a particular view. If so, this may lead to bias and that data should be discarded. For example, the motor industry may give different figures for car efficiency to an environmentalist or interpret the figures differently. After all, the number of people in a car or train is not precisely known and assumptions may be made favourable to the argument being presented. You must always be careful to check how the data is being interpreted (or misinterpreted). But because of the variation and associated (hidden) costs, the figures must be considered indicative only (particularly as the same volume or mass of different fuels do not have the same energy content).
This data is best represented by a bar chart. What emerges from the data is the great advantage of the wheel (and the relative inefficiency of the walking process) and the importance of reducing friction.
You should note that a straightforward comparison in the context of fuel/energy saving is not easy. One also has to consider if journeys are necessary, and ways of reducing the number of journeys. It is claimed that short car journeys are unnecessary, and that people should walk. Another is car sharing, as this moves more persons per journey without the additional vehicle.
|
Transport Mode |
Number of people |
Person-miles travelled per gallon of fuel |
|
Walking |
1 |
235 |
|
Cycling |
1 |
653 |
|
Light Train |
Full |
1400 |
|
TGV |
Full |
630 |
|
Commuter Train (0.5 tonne/seat) |
Full |
500 |
|
Aeroplane (modern) |
Full |
85 |
|
Aeroplane (25 years old) |
70% |
20 |
|
Car |
1 |
36 |
|
Car |
Full |
160 |
|
Compact Car |
3 |
200 |
|
SUV |
1 |
7 |
|
Helicopter |
Full |
20 |
|
Minibus |
Full |
308 |
|
Volvo Luxury Coach |
Full |
520 |
|
Ferry |
Full |
400 |
Projections for Future Energy Demand
The UK Government have developed a core analysis of how the UK energy and emissions system could evolve under central assumptions about how the system drivers will change. The government report is available online if you would like to access it. It includes government policies which have been implemented, adopted, or planned as at Aug. 2019.
There are significant uncertainties in these projections. The potential impacts of the Covid-19 pandemic on future energy consumption and emissions are also highly uncertain, and this document does not seek to quantify them. We will keep this matter under review in light of the developments with the Covid-19 pandemic.
Projections of energy demand and emissions outside the power sector are produced by applying standard statistical techniques. These project forward energy demand and emissions based on trends and relationships in past data.
Referring to Figure 6 below, the total Final Energy Demand (FED) will continue to fall until 2026 133Mtoe to 140Mtoe. By 2040, the total FED is to be around 135Mtoe slowly rising as the effects of policies diminish and macroeconomic drivers. The lower FED is mainly due to the decreased demand for oil products and for natural gas in the residential and industry sectors.
Transport (6b): By 2040 demand will fall by 16% as a result of increased use of electric vehicles and biofuels.
Residential (6c): By 2040 demand is due to increase by 30% as a result of growth in the number of households, changes in household income, future weather and how retail fuel prices will change.
Industry (6d): By 2040 demand will fall by 24%. This is because demand for electricity, solid fuels and renewables is higher, while petroleum products and natural gas is lower.
Services (6e): By 2040 demand is expected to rise by 7%. This is due to the demand of electricity decreasing and oil increasing following the DUKES 2019 relocation.
A more in-depth view can be seen from this 2019 government report if you would like to read it.
Figure 6: Final Energy Demand by fuel and consumer sector, 2008 to 2040. open government license.
Referring to Figure 6, it is predicted that primary energy demand will fall by 11% between 2018 and 2025 from 200 to 179Mtoe, then remain constant to about 2035, them rise to 183Mtoe by 2040.
Figure 6a: Renewables, nuclear and other electricity demand increases steadily to 2040.
Primary energy increases by 36% capable of 29% of total primary energy demand.
Figure 6b: Solid fuels demand rapidly declined in 2013 and is expected to remain low. Electricity generation has switched to using more renewables, waste, and natural gas. By 2040 it is expected that less than 2% of total energy demand will be generated from sold fuels.
Figure 6c: Oil and Natural Gas demand declines 19% by 2040. Result from increasing use of electricity and biofuels for road purposes.
Renewables and nuclear impact the electrical generation from natural gas.
Figure 7: Primary Energy Demand by Fuel type, Mboe. open government license.
Activity 3
How does world population affect the future demand of energy?
Assume a world population in 2021 of 7.9 billion, rising by 1% annually. Calculate the expected population by 2050 using a spreadsheet. Chart the results.
Growing populations and increasing standards of living for many people in developing countries will place even more demand on energy resources. As countries develop, their populations will require more energy. As wealth increases so does the demand for energy.
As the size of a population increases, so does its energy consumption. It has been suggested that the size of the population the planet is able to sustain depends on the amount of energy sources available. With most traditional sources of fuel already used to their maximum capacity and while the search for scalable and sustainable alternatives continues, the question of how population growth affects demand for energy is important to consider.
As the cost of energy rises, we can expect this to affect the population growth rate. The effect though is unpredictable.
The population growth can be calculated using the spreadsheet shown below. Labelling A1 Year and B1 Pop. (G). Enter 2021 in A2 and 7.9 into B2. Enter the equation =A2+1 into A3 and =B2*1.01 into B3. Fill them all down to row 31. You may improve the formatting and annotate the data if you wish.
|
Year |
Pop. (G) |
|
2021 |
7.9 |
|
2022 |
7.979 |
|
2023 |
8.05879 |
|
2024 |
8.139378 |
|
2025 |
8.220772 |
|
2026 |
8.302979 |
|
2027 |
8.386009 |
|
2028 |
8.469869 |
|
2029 |
8.554568 |
|
2030 |
8.640114 |
|
2031 |
8.726515 |
|
2032 |
8.81378 |
|
2033 |
8.901918 |
|
2034 |
8.990937 |
|
2035 |
9.080846 |
|
2036 |
9.171655 |
|
2037 |
9.263371 |
|
2038 |
9.356005 |
|
2039 |
9.449565 |
|
2040 |
9.544061 |
|
2041 |
9.639501 |
|
2042 |
9.735896 |
|
2043 |
9.833255 |
|
2044 |
9.931588 |
|
2045 |
10.0309 |
|
2046 |
10.13121 |
|
2047 |
10.23252 |
|
2048 |
10.33485 |
|
2049 |
10.4382 |
|
2050 |
10.54258 |
Create an X-Y chart of column A against column B. This should be shown as in the line graph below.
Current Energy Use by Sector
We have seen that to reduce energy demand, population growth must be controlled and energy has to be used more effectively. But not all primary energy is used in the same way. It is desirable to break down energy use by sector to see how it is being currently used, and thereby understand the role energy plays in society (and economic development).
Formally, sectors arise from the subdivision or grouping of related components of an economic system into groups. In terms of energy use, it is convenient to identify the domestic, services or commercial, transport, and industry (including agriculture) sectors. This kind of division is useful because each sector requires its own specific policies and regulatory action to affect a reduction in energy consumption.
Figure 8: How energy was used in the UK from 1970—2019. open government license.
Figure 8 shows the long-term trends in consumption by sector and fuel; by sector, the most notable element is the growth in transport consumption and fall in industrial. By fuel, coal has fallen considerably since 1970 (by 96 per cent) with gas consumption more than tripling (though has since fallen by a quarter since consumption peaked in 2001).
Total energy consumption in the UK decreased by 1.4 million tonnes of oil equivalent (Mtoe) (or 1.0 per cent) between 2018 and 2019 to 142.0 Mtoe.
All sectors saw a fall in consumption with almost half of the total decrease (45 per cent) being accounted for by the industrial sector with a further quarter by the domestic sector.
With the exception of bioenergy and waste, all fuels saw a decrease particularly petroleum which fell by 0.9 Mtoe (1.4 per cent).
Bioenergy consumption increased by 0.5 Mtoe (7.6 per cent) with three quarters of the increase being liquid biofuels consumed in transport offsetting to some extent the fall in petroleum in that sector. Overall, transport consumption fell by just 0.4 per cent.
Of course, energy use in these sectors can be sub-divided further. Refer to Energy Consumption UK 2020 for more detail.
The domestic sector is the most responsive to temperature changes as a larger proportion of consumption is used for space heating. Between 2018 and 2019, the average temperature fell very slightly (from 10.6 degrees Celsius to 10.5 degrees Celsius) having a limited impact on consumption, which actually fell very slightly.
Services refers to shops, supermarkets, and non-manufacturing businesses.
Industry is associated with manufacturing and is energy intensive because of the high degree of automation and mechanisation.
Transport can be divided between the distinct modes of transport (through alternative categorisations are possible). Fig. 9 shows a particular division for the UK.
Figure 9 Division of energy use by mode of transport. open government license.
Figure 9 (left) shows Petrol and Diesel (DERV) consumption for cars 1970 to 2018. In particular, it highlights diesel’s increasing share (for all vehicles), notably from the early 1990s onwards until 2017 when diesel narrowly overtook petrol demand. Although diesel demand remained marginally higher in again in 2018, consumption fell, by 1.7 per cent due to increasing volumes of biodiesel supplied.
Cars represent the largest consumers in road transport consumption. Other road transport vehicles’ consumption is shown in Figure 8 (right).
Ultimately, in spite of the convenience of division of use by sector, the amount of energy consumed depends on the individual and the choices he or she makes. The term carbon footprint is used to quantify our use of energy in terms of its effect on the environment (which we will consider in detail later). We are not concerned with environmental effects here though, but only in the quantity of raw material consumed. You should bear in mind that one tonne of oil (1 toe) energy can produce between 0.6 and 1.2 tonnes of carbon depending on the fossil fuel type used for generation.
Activity 4
List the measure that could be taken to reduce energy consumption in each of the sectors listed in the text.
(Do not be concerned for the moment about the costs or the practicalities of implementing these measures.)
Domestic
⇒ Use CFL or LEDs for illumination
⇒ Cook in bulk
⇒ Reduce refrigeration capacity
⇒ Add insulation, double glazing and draft-proofing
⇒ Reduce ambient temperature
⇒ Do not leave appliances on standby
⇒ Use more efficient charging mechanisms
⇒ Recycle materials and goods
⇒ Higher level of occupancy
⇒ Use of heat pumps
⇒ Smaller homes
⇒ Regular servicing of heating systems
⇒ Provide energy usage displays for feedback
⇒ Improved building design
[Generation losses]
⇒ Recovery of heat from electricity generation
Commercial
⇒ Avoid over-illumination
⇒ Promote internet sales
⇒ Use less packaging
⇒ Use of local services and produce/products
⇒ Monitor and review efficiency of heating system
⇒ Introduce intelligent energy control systems
⇒ Use of ‘smart glass’
Industrial
These can be examined in detail by category: Production of materials, manufacturing of products; construction; agriculture; resource management.
Transportation
⇒ More efficient vehicles
⇒ Use of public transport
If you have enjoyed this topic and wish to read further, more notes can be found by following the link below. You will require Microsoft Publisher to open the file: