Wednesday, May 31, 2006

Accidents in the energy sector

One of the measures for sustainability of energy systems is their (low) level of risk. This can be measured based on the occurrence of severe accidents in the past, or, insofar possible, through model calculations.

The Paul Scherrer Institute (PSI) in Villingen, Switzerland owns the world's most comprehensive database on severe accidents in the energy sector. Accidents are considered as 'severe' if they have one of the following consequences: at least five fatalities or at least ten injured or at least 200 evacuees or an extensive ban on consumption of food or releases of hydrocarbons exceeding 10,000 t or enforced clean-up of land and water over an area of at least 25 km2 or economic loss of at least five million USD(2000).

The database not only includes accidents with the production of energy, but covers the entire energy supply chain, since accidents occur in each stage, during exploration, transport, processing, storage, distribution until waste treatment and disposal.

The PSI database ENSAD (Energy Related Severe Accident Database) contains currently 18,400 entries, mainly from the period 1969 { 2000. Comparisons between fossil energy carriers, hydro and nuclear power can be summarised as follows for this time span. Severe accidents are by far more frequent in emerging and developing nations compared to industrialised OECD countries with their distinct safety culture. Over the past 30 years, the OECD countries experienced for coal, gas (natural gas) and liquified gas (LPG, mineral products) a respective total of 75, 90 and 59 severe accidents with at least 5 fatalities, and with oil even 165. Hydro and nuclear power with no severe accident with direct fatalities are clearly less vulnerable, but the maximum possible hypothetical consequences could be very large.

Compared to the rare severe accidents, we see relatively frequent small accidents, especially with renewable energy. Systematic central data on this subject is collected only on a limited scale, which explains why data is often incomplete.

Through improvements in technology and training, as well as the optimisation of the interaction between man and machine, the number of severe accidents, as well as their impact on mankind and the environment can be significantly reduced.

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