Action taken on NZ's most potent greenhouse gas
26 July 2004 Media Statement
Action taken on New Zealand's most potent greenhouse gas
Government, national grid operator Transpower, electricity generators and large electricity users will today sign a voluntary agreement to minimise emissions of sulphur hexafluoride (SF6), the most potent greenhouse gas.
Through the agreement, users of SF6, mainly used in electricity transmission and distribution systems, undertake to:
- adopt best practice
to minimise SF6 emissions
- set and meet emissions targets (in the case of major users), and
- report on SF6 use in accordance with internationally recognised guidelines.
In turn, the Government has reaffirmed that it will exempt users of SF6 from costs arising from its use under climate change policies.
“I welcome the responsible stance being taken by users towards minimising sulphur hexafluoride emissions," says Energy Minister and Convenor of the Ministerial Group on Climate Change, Pete Hodgson.
"Transpower is committed to minimising emissions of this greenhouse gas, and the signing of the agreement provides a useful framework within which this goal can be achieved," says Transpower’s Chief Executive Dr Ralph Craven.
Transpower worked with the Government on behalf SF6 users in the development of the agreement.
The other electricity users who are being invited to sign the agreement include: Vector, Meridian Energy, Mighty River Power, Genesis Power, Contact Energy and Comalco.
Questions & answers about sulphur hexafluoride
Sulphur hexafluoride (SF6) is a synthetic, inert, non-flammable, non-toxic, odourless and colourless gas five times heavier than air. It is exceptionally stable once released into the atmosphere with an estimated lifetime of 800 to 10,000 years. It has the highest global warming potential (GWP) of all known substances - 23,900 over 100 years.
Where is SF6
The main use of SF6 globally is in electricity transmission and distribution systems. SF6 has excellent insulating properties and is the preferred insulator for high voltage electrical supply equipment such as: substations, gas-insulated switchgear and circuit breakers. This usage accounts for 80% of the total annual emissions. Alternatives are available but they do not perform as well and carry their own equally undesirable environmental consequences.
What companies use SF6 in New
Transpower is the greatest user of SF6 with around 90% of the stocks in New Zealand. It also has the most complete data on the stocks of SF6 that it holds (estimated to be 32 tonnes in 2002). Of the electricity distribution companies, only Vector holds a significant quantity, estimated to be about three tonnes. Meridian Energy, Mighty River Power, Genesis Power and Contact Energy, as well as large industrial sites account for most of the remainder. Minor quantities (less than 20kg per year) are used for research purposes and for highly specialised industrial uses. These are not addressed by the MOU.
much SF6 is used in New Zealand
The total stock of SF6 in New Zealand in 2002 was estimated by Transpower to be less than 40 tonnes. A detailed study carried out by CRL Energy Ltd on SF6 emissions as part of the 2004 NZ Inventory of Greenhouse Gas Emissions gives a more accurate estimate of the total national stock of 33.2 tonnes in 2003.
Although SF6 has an extremely high GWP it only contributes 0.1% of New Zealand’s greenhouse gas inventory.
Why a voluntary MOU?
Because the actual emissions of SF6 are very low and because the major users showed a high degree of willingness to limit their emissions, a regulatory approach was not considered necessary. This form of agreement provides a good mechanism for monitoring SF6 use and ensuring that emissions are minimised, without placing undue costs or restrictions on the electricity supply industry.
In the unlikely event that circumstances alter and there is a significant rise in emissions, then the agreement does not preclude more direct actions being taken.