Emission Reduction Unit
The emission reduction unit (ERU) is an emissions unit issued under a Joint Implementation project in terms of the Kyoto Protocol. An ERU represents a reduction of greenhouse gases under the Joint Implementation mechanism, where it represents one tonne of CO
2 equivalent reduced.
To allow comparison between the different effects of gases on the environment, scientists have defined multipliers for gases that compare their greenhouse potency (global warming potential) relative to that of carbon dioxide.
One example of a Joint Implementation project resulting in an emission reduction unit, is the production of biogases by landfill sites. These gases consist of mainly methane which escapes to the atmosphere if it is not collected. The main reason for dealing with methane is that it has a 100-year global warming potential multiplier of 25 compared to carbon dioxide (i.e. has 25 times the greenhouse potency). Collection of methane is usually accompanied by its combustion. Burning one tonne of methane produces nearly 3 tonnes of CO
2, thus reducing its greenhouse effect by (25-3=22) ERU.
In December 2012, ERU prices crashed to a low of 15 euro cents before recovering to 23c after news that EU’s Climate Change Committee was to vote on a ban of ERUs from countries that have not signed up to a second commitment period under the Kyoto Protocol.
In January 2013, Bloomberg reported that emission reduction unit prices declined 89 percent in 2012 
- "Glossary of climate change acronyms 'E'". UNFCCC. Retrieved 2010-02-23.
- ipcc-wg1.ucar.edu PDF Araxto, P. et al. (2008) IPCC WG1 AR4 Report
- Allan, Andrew (12 December 2012). "U.N. offsets crash to 15 cents ahead of EU ban vote". Point Carbon. Retrieved 16 December 2012.
- Bloomberg (1 January 2013). "European carbon permit prices cap another losing year". The Age. Retrieved 14 January 2013.