Energy production

8 hours

8.1 – Energy sources

Essential idea: The constant need for new energy sources implies decisions that may have a serious effect on the environment. The finite quantity of fossil fuels and their implication in global warming has led to the development of alternative sources of energy. This continues to be an area of rapidly changing technological innovation.
Nature of science: Risks and problem-solving: Since early times mankind understood the vital role of harnessing energy and large-scale production of electricity has impacted all levels of society. Processes where energy is transformed require holistic approaches that involve many areas of knowledge. Research and development of alternative energy sources has lacked support in some countries for economic and political reasons. Scientists, however, have continued to collaborate and share new technologies that can reduce our dependence on non-renewable energy sources.
• Specific energy and energy density of fuel sources
• Sankey diagrams
• Primary energy sources US energy 2010 - Sankey diagram World energy - Sankey diagram
• Electricity as a secondary and versatile form of energy The generator Power grid simulation
• Renewable and non-renewable energy sources Laser fusion movie Inertial confinement fusion How IFE works Why we need fusion movie JET Project Photovoltaic cell animation Wind farm bird death lawsuit
Applications and skills:
• Solving specific energy and energy density problems
• Sketching and interpreting Sankey diagrams
• Describing the basic features of fossil fuel power stations, nuclear power stations, wind generators, pumped storage hydroelectric systems and solar power cells
• Solving problems relevant to energy transformations in the context of these generating systems
• Discussing safety issues and risks associated with the production of nuclear power
• Describing the differences between photovoltaic cells and solar heating panels
• Specific energy has units of J kg-1; energy density has units of J m-3
• The description of the basic features of nuclear power stations must include the use of control rods, moderators and heat exchangers
• Derivation of the wind generator equation is not required but an awareness of relevant assumptions and limitations is required
• Students are expected to be aware of new and developing technologies which may become important during the life of this guide
Data Booklet reference:
Power = energy / time
Power =(1/2) Arv 3
• The A is the cross-sectional area of the blades of a wind turbine. Thus A = pr 2, where r is the radius of the blades. The r represents the density of the fluid that is passing through the blade area. In the case of air, r is approximately 1.2 kg m3. The v represents the speed of the fluid, in this case air, passing through the blade area.
• Generators for electrical production and engines for motion have revolutionized the world (see Physics sub-topics 5.4 and 11.2)
• The engineering behind alternative energy sources is influenced by different areas of physics (see Physics sub-topics 3.2, 5.4 and B.2)
• Energy density (see Chemistry sub-topic C.1)
• Carbon recycling (see Biology sub-topic 4.3)
Aim 4: the production of power involves many different scientific disci-plines and requires the evaluation and synthesis of scientific information
Aim 8: the production of energy has wide economic, environmental, moral and ethical dimensions

8.2 – Thermal energy transfer

Essential idea: For simplified modelling purposes the Earth can be treated as a black-body radiator and the atmosphere treated as a grey-body.
Nature of science: Simple and complex modelling: The kinetic theory of gases is a simple mathematical model that produces a good approximation of the behaviour of real gases. Scientists are also attempting to model the Earth’s climate, which is a far more complex system. Advances in data availability and the ability to include more processes in the models together with continued testing and scientific debate on the various models will improve the ability to predict climate change more accurately.
• Conduction, convection and thermal radiation
• Black-body radiation Blackbody radiation
• Albedo and emissivity
• The solar constant The sun and its variations
• The greenhouse effect The greenhouse effect simulationMilankovitch cycles and the ice ages
• Energy balance in the Earth surface–atmosphere system Glacier model
Applications and skills:
• Sketching and interpreting graphs showing the variation of intensity with wavelength for bodies emitting thermal radiation at different temperatures
• Solving problems involving the Stefan–Boltzmann law and Wien’s displacement law
• Describing the effects of the Earth’s atmosphere on the mean surface temperature
• Solving problems involving albedo, emissivity, solar constant and the Earth’s average temperature
• Discussion of conduction and convection will be qualitative only
• Discussion of conduction is limited to intermolecular and electron collisions
• Discussion of convection is limited to simple gas or liquid transfer via density differences
• The absorption of infrared radiation by greenhouse gases should be de-scribed in terms of the molecular energy levels and the subsequent emission of radiation in all directions
• The greenhouse gases to be considered are CH4, H2O, CO2 and N2O. It is sufficient for students to know that each has both natural and man-made origins.
• Earth’s albedo varies daily and is dependent on season (cloud formations) and latitude. The global annual mean albedo will be taken to be 0.3 (30%) for Earth.
Data Booklet reference:
P = esAT 4
lmax = 2.90´10-3/ T
I = power / A
albedo = total scattered power / total incident power
• The P represents the power emitted or absorbed by a body having emissivity e, surface area A and absolute temperature T. The Stefan-Boltzmann constant s = 5.67´10-8 W m-2 K-4. For a sphere, A = 4pr 2. The lmax represents the wavelength of the most intense blackbody radiation at a particular absolute temperature T. The I represents the intensity of radiation.
• The concern over the possible impact of climate change has resulted in an abundance of international press coverage, many political discussions within and between nations, and the consideration of people, corporations, and the environment when deciding on future plans for our planet. IB graduates should be aware of the science behind many of these scenarios.
Theory of knowledge:
• The debate about global warming illustrates the difficulties that arise when scientists cannot always agree on the interpretation of the data, especially as the solution would involve large-scale action through international government cooperation. When scientists disagree, how do we decide between competing theories?
• Climate models and the variation in detail/processes included
• Environmental chemistry (see Chemistry option topic C)
• Climate change (see Biology sub-topic 4.4 and Environmental systems and societies topics 5 and 6)
• The normal distribution curve is explored in Mathematical studies SL sub-topic 4.1
Aim 4: this topic gives students the opportunity to understand the wide range of scientific analysis behind climate change issues
Aim 6: simulations of energy exchange in the Earth surface–atmosphere system
Aim 8: while science has the ability to analyse and possibly help solve climate change issues, students should be aware of the impact of science on the initiation of conditions that allowed climate change due to human contributions to occur. Students should also be aware of the way science can be used to promote the interests of one side of the debate on climate change (or, conversely, to hinder debate).


This is the complete problem set for Topic 8 - the same one I hand out. If you lose yours, you can download this one to replace it.


These are the Formative Assessments (practice) that you will do in order to prepare yourself for the Summative Assessments (evidence of proficiency). You can expect to receive a mark of at least Proficient on the Summative Assessment if you understand everything on these Formative Assessments.


Project marks are meant to replace summative assessment marks. Projects are your last opportunity to demonstrate your proficiency in meeting the standards of the assessment criteria.


These PowerPoints from the previous cycle are extensions of Topic 8.1 and show a bit more detail. Don't confuse their "old" numbering with the "new."

As a data-filled extension to Topic 8.1, check out this document. It was put together by British Petroleum and is a report on world energy usage (not just bp gas) and is highly detailed. It is a thorough source of statistics on coal, oil, gas, nuclear and hydroelectric power costs, proven reserves, and production.

This document shows the overall power trends in the US over the decade ending in 2011. It includes both fossil- fuel and non-fossil-fuel derived power production.

This document is an exhaustive description of nuclear safety issues. Read it and weep.

Extending Topic 8.2, the Climate Change 2008 final pamphlet puts it all in a nutshell. It is a good resource for believers in man-made global warming. There is probably a newer version out there, but I haven't looked lately. There are lots of excellent graphics included in this small book.

An excellent book by Tim Flannery is called The Weather Makers (and subtitled How Man Is Changing the Climate and What It Means For Life on Earth). Whether you are embroiled in the global warming controversy or not, the book is a rich source of everything having to do with global warming and cooling cycles. The Milankovich cycles are explained and Flannery's book is the source for most of that subject. There is a website for this book (and a newer one): The Weather Makers.

These PowerPoints from the previous cycle are extensions of Topic 8.2 and show a bit more detail. Don't confuse their "old" numbering with the "new." The Global warming.pptx explains the Milankovich cycles thoroughly. If you are a global warming buff, read up on these cycles. And look at this video: Earth's orbit about Sun over time.

These extensions to are chock full of theory and math. If you like calculus, look at the first document. If you want to argue with people who say volcanoes put more carbon dioxide in the atmosphere than humans, read the second document.

The link Total Precipitable Water takes you to some really nice maps showing how complex modeling of world weather patterns must be. It shows satellite images of the total water column in the atmosphere at any time. This is not cloud cover, but rather water content from the ocean surface to the upper atmosphere.