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Yes AD combined with CHP or even CHCP. What is all this acronym stuff eh?
AD is Anaerobic Digestion, its the sort of process that happens in a sewage works where all that nasty stuff is broken down by 'good' bacteria. What is left is largely safe but has given off lots of methane gas and CO2, along with some other trace stuff. Anaerobic means 'without Oxygen'.
So to create bio-methane by digestion of waste products has to be "Carbon (dioxide) Negative" as it is removing methane from being released into the atmosphere! See article below about atmospheric methane - CLICK HERE
Now that Methane is what we need. Its almost the same as Natural Gas that you buy at home. So it can be 'cleaned up' and sent down pipes to the gas mains or it can run a gas fired electricity generator.
But rather than just generate electricity, we also need to look at how effective the burning of gas in an engine really is. When gas is burned in say a modified car engine to drive a shaft to turn a generator to produce electricity, there are loses. These loses affect the efficiency of turning the energy value of gas into electricity. It is disappointing to discover that only around 20-25% of the gas burnt produces the electricity. The rest is 'low grade' waste heat.
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| The Chinese have over 2 million of these AD-CHP Units |
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Combined Heat and Power (CHP) is not a new idea to the UK. Woking for example, has a large district heating network which makes considerable carbon savings and the Immingham plant on the Humber is a large industrial example. Yet when one compares the UK to Sweden, UK CHP seems very underdeveloped in comparison. Here we would like to discuss just what makes Swedish CHP so great and what the future holds in the UK for the technology.
We won't cover the technical aspects to CHP cogeneration here, as just an introduction is needed. The principle is simple however; whether on a micro scale or on an industrial scale, power production and industrial processes usually create a lot of heat, which is wasted ''potential'' energy. CHP cogeneration aims to take this waste heat and make it useful, increasing the efficiency of the installation. Often this will mean piping the heat to nearby buildings to be used for domestic, industrial heating, or even, additionally [by the use of Absorption Chillers] chilled water for air conditioning! Known as TRI-Generation
Example of Sweden – wide adoption of combined heat and power technology
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Notice that the methane levels have jumped up to 1800 ppb in the last 50 years [Blue Line] the global mean temperatures [Grey Line] used to mirror methane spikes, but now something else is happening graph source https://methanelevels.org
RECENT AND HISTORICAL DATA [Post 1983]
Since 1983, globally-averaged CH4 levels have been collected and updated monthly as new samples are added to the analysis. A 3 month lag is required to ensure the data has been properly vetted for possible contamination. Prior to 1983, methane levels have been extracted from ice core data from Antarctica.
Globally-averaged, monthly mean atmospheric methane abundance is determined from marine surface sites. The Global Monitoring Division of NOAA's Earth System Research Laboratory has measured methane since 1983 at a globally distributed network of air sampling sites.
Credits: Ed Dlugokencky, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends_ch4/)
METHANE
E. Dlugokencky, S. Houweling, in Encyclopedia of Atmospheric Sciences, 2003
Biological Production
Decomposition of organic matter by bacteria under anaerobic conditions in, for example, wetlands, flooded soils, sediments of lakes and oceans, sewage, and digestive tracts of ruminant animals, involves complex simultaneous processes that can produce methane as a byproduct.
Read more: Rising Methane Levels - and impact on Climate Change