Additional guidance from the Department for Environment, Food and Rural Affairs, and from the Welsh Assembly Government
AQ 24(04)
Amendments of PG 1/4(95) Gas Turbines, 20-50 MW Net Rated Thermal Input
[THE AMENDMENTS ARE IDENTIFIED BY ITALICS IN THE NOTE BELOW]
This note amends PG1/4(95), following its second review. The note has not been republished in the new format because of the relatively few amendments and small number of regulated installations.
The amendments and new text at points 6 onwards below should be treated as statutory guidance under both section 7(11) of the Environmental Protection Act 1990 and also Regulation 37(1) of the Pollution Prevention and Control (England and Wales) Regulations 2000, SI 1973.
For the purposes of regulation under the Pollution Prevention and Control Act 1999, the schedule of activities, installations and mobile plant is contained in Schedule 1 to the Pollution Prevention and Control Regulations 2000, SI 1973 as amended. The timetable for implementation is contained in Schedule 3 to the same regulations.
Background
1. Advances in combustion engineering have led to the introduction of dry low NOx burners for gas turbines, which emit lower concentrations of nitrogen oxides (NOx) than those in PG1/4(95). These lower limits are to be applied to new gas turbines.
2. Improvements in nitrogen oxide emissions from new plant might be achieved at the expense of increasing other emissions. To prevent this, a carbon monoxide limit and monitoring are introduced for new plant.
3. Since PG1/4 was last revised, Directive 1999/32/EC on the Sulphur Content of Certain Liquid Fuels (SCCLF) has set dates and limits on the sulphur content of residual and gas oil burnt in Part B and other plant. Transposed by the Sulphur in Liquid Fuels (England and Wales) Regulations 2000, SI 1460, the changes have already been notified to local authorities in a letter from DETR and the National Assembly for Wales dated 22 June 2000.
The dates and limits that are incorporated into PG1/4 are:
From 1 July 2000, gas oil must contain 0.2% by mass of sulphur or less;
From 1 January 2008, gas oil must contain 0.1% by mass of sulphur or less.
4. The Pollution Prevention Control (England and Wales) Regulations 2000 SI1973 (PPC Regs) contain a definition of Part A combustion activities which differs a little from that for combustion processes in the Environmental Protection (Prescribed Processes and Substances) Regulations 1991 SI472 as amended:
- the PPC Regulations define combustion activities by the 'rated thermal input'. Previously the 'net rated thermal input' was used.
- for information, a change has been made to the aggregation rule for Part A activities. Under IPPC, all combustion appliances are added together. Previously boilers and gas turbines, for example at a combined heat and power plant, would not have been added together.
Amendments
5. At the start of Clause 2, add the words "Under LAPC"
6. It was proposed in a consultation paper issued on 10 December 2003 to amend the PPC Regulations. The proposal is to amend section 1.1 of Schedule 1 to the Regulations to insert the word "net" in paragraphs (a) - (c) of the Part B definitions.
Until such time as the amendment is made, add to the end of Clause 2 a new paragraph:
"Under LAPPC, the gross rated thermal input should be used instead of the net rated thermal input. The gross rated thermal input is larger than the net rated thermal input by the amount of heat needed to vaporise water produced by the combustion of hydrogen in the fuel (the latent heat of vaporisation) plus any heat added to fuel or air before combustion. For coal and coke this makes little difference. For fuel oil the gross rated thermal input is about 5% above net rated thermal input. For natural gas, the increase is about 10%."
7. At the start of Clause 9, add the words "Under IPC and LAPC"
8. At the end of Clause 9, add a new Clause 9A
"9A. Under IPPC and LAPPC, the Part A aggregation rule is simpler and applies to all combustion appliances operated on the same site by the same operator. So, for example, the net rated thermal input of gas turbines and boilers are added together and, if the aggregate is over 50 MW, they are Part A. Plant affected by the change may include combined heat and power plant where gas turbines and boilers are commonly operated together. The lower threshold for LAPPC is similar to LAPC i.e. 20MW per single combustion appliance."
9. In Clause 19, delete the words and numbers from 'Natural Gas Fired' to 'ISO net base efficiency' inclusive, and replace with the following table and footnotes:
|
Fuel |
Processes |
Nitrogen oxides (expressed as mg/m3 |
Carbon monoxide mg/m3 |
|
Natural gas fired
|
New and existing turbines operating for less than 100 hours per year (from date of initial authorisation) |
400 |
|
|
Existing turbines operating for more than 100 hours a year |
125* |
|
|
| New turbines operating for more than 100 hours a year | 60* | 60* | |
| Liquid or petroleum derived gas fired | New and existing turbines operating for less than 100 hours a year (from date of initial authorisation) | 600 | |
| Existing turbines operating for more than 100 hours a year | 165* | ||
| New turbines operating for more than 100 hours per year | 125* | 60* |
The carbon monoxide limit should be applied when new plant is operating at over 70% of capacity'
*Based upon an efficiency of 30%. For more efficient turbines the emission limit (EL) may be calculated using the following formula
| Corrected EL mg/m3 = | EL mg/m3
30
|
x ISO net base efficiency %
|
10. Delete Clause 20 and replace it with the following Clause:
" 20. The sulphur content of gaseous fuel should normally not exceed what is equivalent to 70mg/MJ. To comply the Sulphur in Liquid Fuels (England and Wales) Regulations 2000 SI 1460; for liquid fuels burnt before 1 January 2008, the sulphur content must not exceed 0.2% by mass, and from 1 January 2008, the sulphur content of liquid fuel must not exceed 0.1% by mass.
11. In Clause 26, directly after the phrase 'nitrogen oxides' in the first line of the first paragraph and in the first and third lines of the second paragraph, add the following words: "and carbon monoxide"
12. In Clause 28, directly after the phrase 'nitrogen oxides' add the following words: "and carbon monoxide"
13. In Appendix 2 Clause 10 add to the end of the third Paragraph, the following sentence: 'Compliance demonstrated when operating at less than 70% of capacity should also be accepted'.
AEQ/Defra
6th October 2004
Page published: 7 October 2004