| Overview |
| General background - market economy |
| General background - carbon trading |
| Brief notes on "comments on the Stern Review by leading economists" and links to them |
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| Overview |
| Basic science of Carbon including the carbon cycle |
| Photosynthesis & Respiration |
| Combustion - Energy production from carbon based fuels - the science |
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| Overview |
| Energy production from carbon based fuels (technology) |
| Alternative sources |
| Innovation and development |
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| Overview |
| Forest, Ice and Ocean |
| Land usage and impact on climate |
| Developing nations, including political aspects |
| Social change, population and industry |
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| Overview |
| Lesson plans, guides and pedagogy |
| Activities, tasks and assignments |
| Questions & Discussions |
| Software, Web 2.0 tools and data including images etc |
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| Glossary of terms, acronyms etc |
| Links to relevant sections in main National curriculum, GCSE and GCE syllabuses |
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Combustion:
energy production from carbon based fuels – the science Despite
increased use of nuclear and alternative energy sources for electricity
generation, over two thirds (2004 data) of fuels used are fossil and therefore
carbon based; mainly coal, gas and oil, but also including wood, peat and
even bitumen. Whether the fuel is used directly e.g. in transport or heating,
or indirectly for electrical power generation, the same chemistry i.e. oxidation
or combustion of the fuel releases the energy, predominantly in the form
of heat and with the emission of CO2. What matters is the efficiency
with which this energy is extracted and used AND whether the carbon comes
from fossil sources. This enables us to entertain use of allegedly “greener”
carbon based fuels such as bio-ethanol, bio-diesel etc. Similarly whether
the fuel is used in a car or a power station makes little difference to
the basic chemistry BUT may make a difference in terms of efficiency and
emissions e.g. catalytic converters on cars, carbon capture and storage
in power stations. We make use of the law of conservation of energy to transform
the heat energy produced to other forms of energy that we require, most
frequently via kinetic energy in transport or in generating electricity.
 The
process of combustion is a typical exothermic oxidation reaction, and would
be thought to be simple. However, the precise conditions alter the chemistry
for example depending on the availability of oxygen which determines whether
the combustion is complete or incomplete and therefore what the products
are and how much energy is released, and depending on the other substances
present – air for example contains mainly nitrogen and coal, wood,
oil and gas have many impurities including sulphur.From the above we see that the use of fossil fuels can be improved in two related ways: improving the quality of emissions, increasing efficiency of energy output per unit mass of fuel. Carbon fuels which are not fossil fuels also offer an advantage (carbon neutral) because we are not adding to the current carbon by releasing carbon from millions of years ago i.e. in principle the carbon is “captured” by e.g. wheat, made into fuel which then releases back the same carbon. It does not however reduce the carbon level. The chemistry of combustion is well understood and developing methods of reducing emissions and improving efficiency are now a major focus for science and technology. Combustion is referenced in the links but in essence it follows the same basic equations as respiration. The physics however e.g. fluid mechanics of combustion is not covered in this section since it is the carbon chemistry which relates to the Stern Review more directly. Since the energy output from the combustion of a fuel reflects the net effect of making and breaking chemical bonds, it follows that different fuels provide different amounts of energy per unit even when fully combusted. These enthalpies of combustion are available in tables or can be calculated using Hess’s Law. For practical purposes of course, other factors come into play e.g. ease of production or extraction, cost, safety etc. |
  Combustion:
wikipedia entryEurope
Tests Carbon Capture at Coal-Fired Power PlantBiofuels
ukBiofuel
raises global dilemmasBiofuels:
Green energy or grim reaperWhat
is Biodiesel's Energy Balance?World
Coal InstituteNaturalGas.orgFossil
FuelsCalculating
Enthalpies of combustionKey
World energy Statistics 2006 (PDF) |
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