Nottingham City Council has recently released figures showing that in 2007 only 21% of energy from burning waste in the Eastcroft incinerator was sold as heat through the district heating system. That follows an admission by incinerator operator WRG that only just over 10% of the energy was used to produce electricity exported to the grid.
It means over two thirds of the calorific value of the city's waste was wasted. That is worse than the waste of heat in coal-fired power stations.
The Council's portfolio holder for environment and climate change Councillor Katrina Bull was recently quoted as saying that "We have now got one of the most efficient Energy from Waste plants in Europe" (Nottingham Evening Post, 27/2/2010, p8), following a major refit of the incinerator which cost the City and County Councils around £20m over the last three years. She has since said that she did not compare it to efficiencies in Europe, but did say the Eastcroft incinerator is "now very efficient".
We wait with interest to see what data the City can produce to support that claim. So far the City has refused to produce any data after 2007.
Measuring the efficiency of the incinerator is complicated because steam from the incinerator is piped to the London Road heat station operated by EnviroEnergy, a company wholly owned by the City Council. EnviroEnergy uses the steam to produce electricity and then pipes 'waste' heat as steam and hot water around a district heating system which serves around 4,500 homes (mainly in St Ann's) and a number of businesses in the city centre.
Some information about efficiency of the incinerator was given by WRG at a planning inquiry in September 2008. More limited information was given by the City recently. However, the City has refused to give further information, claiming that in their view the outputs of heat and electricity from EnviroEnergy do not have any relevance to calculating the efficiency of the Eastcroft incinerator!!! (A complaint has been made to the Information Commissioner, but this could take a long time.)
An analysis of the data suggests that, of the 406.7GWh calorific value of waste burnt in the Eastcroft Incinerator in 2007,
- 98.9GWh (24%) was 'lost' in the incinerator
- 106.4GWh (26%) was 'lost' in EnviroEnergy
- 16.7GWh (4%) was used as electricity in the incinerator and district heating system
- 59.0GWh (15%) was heat lost in distribution or used in the incinerator
- 125.7GWh (31%) was useful energy sold (10% as electricity, 21% as heat)
One reason for asking for information on EnviroEnergy's heat outputs was to contribute to a government consultation on calculating the efficiency of municipal waste incinerators. This is required by a revised European Waste Framework Directive which will come into force in December 2010. At the moment incinerators are defined as 'disposal' of waste, like landfill, which requires waste to be sourced locally (the 'proximity' principle). In the future if incinerators reach an 'efficiency' threshold they will be defined as 'recovery' and waste can be brought in from a much wider area.
The data for the Eastcroft incinerator in 2007 suggest that how the energy outputs are defined will make a very big difference to the calculated efficiency:
- One possibility would be to say that the energy output from the incinerator is the steam and hot water exported to EnviroEnergy. This is 75.7% of heat energy in the waste.
- A second possibility would be to say that the energy output is the electricity generated and heat distributed by EnviroEnergy. This is 49.5% of energy in the waste - 14.3% as electricity and 35.3% as heat.
- A third possibility would be to only recognise electricity and heat actually sold. This is 31% of energy in the waste - 10.2% as electricity and 20.8% as heat.
(The efficiency formula will multiply electricity by 2.6 and heat by 1.1 and take account of the supplementary energy supplied by gas. This formula would produce 'efficiency' figures for the above three options of 85.8%, 71.6% and 43.3% respectively. A figure above 60% is required for existing incinerators, and 65% for new incinerators.)
If either of the first two options are applied, the Eastcroft incinerator would pass the efficiency threshold even though less than a third of the energy in waste is usefully exported.
The Environment Agency has suggested another way that incinerator operators could pass the efficiency threshold - by basing the calculation on 'plant design figures to avoid any complications due to occasional operational variability'.
(Details of Defra's consultation on the Waste Framework Directive are at:http://www.defra.gov.uk/corporate/consult/waste-framework/index.htmThe document for Stage One of the consultation explains the efficiency formula in para 2.152. The above quote from the Environment Agency is in para 2.182. Consultation on the efficiency formula will be included in a Stage Two consultation later in 2010.)
Background information:
Letter to Katrina Bull, 12 March 2010 - this includes a detailed analysis of data for 2007.
Paper WRG10 - submitted by WRG to a planning inquiry in September 2008, giving data for the existing Eastcroft incinerator on page 2.
Letter from the City Council dated 29 January 2010 - giving an estimate of heat sold by EnviroEnergy in 2007. (This was a response to a request by Nottingham Friends of the Earth member Nigel Lee originally made in June 2009 under Environmental Information Regulations (which require a response within 20 working days). The City has refused to release more recent data comparing heat distributed through the district heating scheme with heat actually sold - on the grounds that public interest in maintaining confidentiality outweighs public interest in releasing the information. A complaint has been referred to the Information Commissioner.)