My inaugural speech, in December 2011, was an event that several hundred people attended at the Delft University of Technology (TUDelft). At the time I promised it would be made climate neutral by the purchase of carbon credits. Netherlands-based Climate Neutral Group helped out, with their complementory gift. It pertains to the purchase of carbon credits that resulted from a Cambodian biogas project.
How it works? Many, if not most human activities emit greenhouse gases. Either directly (i.e. car transportation), or indirectly (electricity generation). A market-based mechanism to reduce greenhouse gas emissions are carbon credits. These are certified reductions that calculate and verify lower emissions for a given source (say, a factory) from a business-as-usual scenario.
An example could be a sugar cane processing plant, which produces sugar with two main residual substances: vinasse and bagasse. Vinasse is basically water with very high levels of organic matter, which is traditionally diverted to a local river or left to evaporate in fields. Here it can form an environmental problem by making the water unsuitable for many organisms, while also generating methane, a strong greenhouse gas.
Bagasse is the woody fiber from the plant that is usually left on the field.
A typical carbon reduction project would seek to productively re-use these two left-over substances. For vinasse this entails diverting these fluids to a lagoon (think footbal sized areas), which is subsequently covered with plastic. In this oxygen deprived (anaerobic) environment methane bacteria thrive, and as a result break down the organic matter into biogas (a mixture of methane and carbon dioxide). After a digestion period of several weeks the water can be safely discharged into the river, while the biogas can be burnt by a power generator to produce electricty for the plant.
The woody bagasse would be dried, and used as biomass to power the furnace at the processing plant that in turn produces steam. As such it often replaces coal, a fossil fuel.
A carbon credit project would precisely calculate these reductions, which can then be sold to companies or individuals that would like to reduce their carbon emissions but cannot do so at low cost.
See the certificate from Climate Neutral Group attached.