Chapter 8: necessity for achieving objectives
Introduction
656. By section 171(1)(c) of the RMA, a territorial authority considering a requirement is, subject to Part 2, to have particular regard to:
Whether the work and designation are reasonably necessary for achieving the objectives of the requiring authority for which the designation is sought.
657. Transpower’s objectives for which the designations are sought are these:
Overall Project Objective
To ensure the continued security and certainty of electricity supply to Auckland, Northland, and parts of Coromandel and Waikato, by constructing and operating a new transmission link (including substations and ancillary facilities) and to upgrade existing assets, in a manner that is safe, efficient and consistent with maintaining current grid reliability standards and which provides flexibility to address future changes in supply.Overhead Line Objective
To facilitate the construction, operation and maintenance of new electricity transmission infrastructure through predominantly rural areas between south Auckland and the central North Island, and to enable the removal and/ or replacement of existing transmission infrastructure.Underground Cable Objective
To provide for an efficient and secure electricity transmission connection to overhead transmission circuits, and its ongoing operation and maintenance, between the existing urban boundary of Auckland and substation facilities.
658. There was no substantial dispute on whether designation, as a planning method, is reasonably necessary. The main issue is whether the work (that is, the proposed grid upgrade itself) is reasonably necessary for achieving the objectives. That was disputed by some submitters. The Board addresses that question first.
Is the work reasonably necessary?
659. Transpower submitted that the Grid Upgrade Project is reasonably necessary to achieve its objectives in that, by providing a new transmission link (including substations and ancillary facilities) and upgrading existing assets, it would resolve current and foreseeable electricity transmission problems of the upper North Island and ensure continued security and certainty of electricity supply; and provide for removal of the existing ARI-PAK line; both in a manner that is safe, efficient, and consistent with maintaining current grid reliability standards; and providing flexibility to respond to future changes.
660. Some submitters disputed Transpower’s submission that the work is reasonably necessary for achieving its objectives. The general theme of their contentions was that the extra capacity of the proposed 400-kV-capable line over a 220-kV line is premature and not reasonably necessary because it is unlikely to be needed for at least a quarter of a century, and with probable changes in technology, in the economic climate, and in the location of new generation in the meantime, it would not be needed even then.
Evidence
Transpower
661. Mr George gave evidence that Transpower is required by the Electricity Governance Rules to ensure the reliability of the transmission system. The basic requirement is to provide a core transmission grid that can withstand the loss of any one component (eg, a circuit) and still meet peak load demand. This is often referred to as a “N-1” security criterion.
662. Mr George asserted that demand growth and the development of new generation sources are the main reasons for grid development taking place. He also advised that other variables, such as investment in non-transmission alternatives, can influence the development of the grid, but do not replace the need for the grid.
663. In cross-examination by Dr McQueen, Mr Coad stated that in relation to forecasts of demand that Transpower is obliged to use the SOO issued by the Electricity Commission, although it has the right to offer an alternate view on that SOO.1 Similarly, Mr George identified that when assessing possible futures for grid investment, Transpower uses the generation scenarios that the Electricity Commission has published in the SOO.2
664. Mr Boyle gave evidence that due to increasing demand for electricity, in the future there will be insufficient capacity in the existing power system at times of peak demand to reliably supply electricity to the Auckland area, including the area north of Auckland. He identified the critical issues as insufficient thermal capacity resulting in an inability to supply the demand, and the possibility of voltage instability at times of peak load which could result in partial or total loss of supply to the upper North Island.
665. Mr Boyle gave his opinion that, at a policy level, there are three key factors that influence the design of a transmission line. These are: providing a reliable and diverse supply; maximising the use of the transmission corridor; and minimising the cost of the line. He stated that system security and diversity are key considerations which are given considerable weighting in any analysis of alternate options.
666. In cross-examination by Ms Brennan about the apparent overcapacity of the proposed grid upgrade, Mr Boyle explained that the line would not be operated to the maximum thermal design capacity because of the need to meet the N-1 security criterion which requires any electricity being generated or transmitted by the equipment that fails to then be taken up by the other circuits supplying that demand without any of these other circuits exceeding 100 per cent of their capability.3
667. The complexity of meeting the N-1 security criterion was added to when Mr Boyle gave evidence about the loading of each circuit being governed by the laws of physics. As a result, Transpower has only a limited ability to modify the power flowing through each circuit. He explained that the natural distribution of the load across the six existing 220-kV circuits, plus the two proposed 400-kV capable circuits, would not be in proportion to the circuits’ ratings, resulting in some circuits being underutilised.
668. A number of submitters questioned the reliance Transpower placed on the demand forecasts in the 2005 SOO, instead of the forecasts in the draft 2007 SOO. Mr Boyle explained that:
At the time of the assessment of the proposal, the Electricity Commission did consider whether it would be appropriate to adopt the scenarios in the draft 2007 SOO, but determined that it would not be appropriate, part way through the process, to adopt scenarios that underlie the draft 2007 SOO. At that time, the draft 2007 SOO had yet to be consulted on, and may have changed as a result of consultation. The Commission did, in any event, include the draft 2007 demand forecasts as a sensitivity in applying the GIT to the proposal.
669. He gave his opinion that, even if the draft 2007 demand forecasts had been used, the “need date” for the line to be commissioned at 220-kV would at best be delayed a year.
670. Mr Boyle also noted that some submitters had suggested that demand has dropped and is trending down over time. He responded that demand is increasing, but the annual rate of increase in the demand forecast is decreasing over time, resulting in a reasonably straight demand curve rather than the exponential demand curve that would be expected if an identical annual growth rate compounded year on year.
671. He noted, by way of example, that the annual growth rate in the demand forecast for central Auckland starts at 4.06 per cent in 2008 and reduces to 2.05 per cent by 2042.
672. Mr Boyle then gave evidence in response to submitters’ suggestions that the demand will never reach levels that would require the change from 220-kV to 400-kV operation. He reported that the development plans are based on the 2005 SOO; noted that the demand curve in the draft 2007 SOO is flatter than the 2005 SOO demand curve, especially in the later stages of the forecast period; and noted that, if the draft 2007 SOO demand forecast is used, the conversion to 400 kV would be delayed by about five years.
673. Mr Boyle explained that this delay may be countered with the adoption of a renewable future with a high percentage of renewables. In his opinion, with a renewable target of 90 per cent by 2025, it was probable that the Huntly coal-fired power plant would no longer be used for baseload generation, and that it was quite likely that the change from 220-kV to 400‑kV operation of the line would occur earlier than forecast, and in any event by 2039.
674. Mr Boyle stated that the GPS requires that, to the extent the Electricity Commission considers the environmental effects of new lines, it should also take into account any longer-term benefits that larger capacity lines may provide by avoiding multiple smaller lines.
675. In his evidence, Mr Boyle described a feature of the 400-kV-capable proposal being the ability to release the additional capacity relatively quickly by changing the operating voltage to 400 kV. His estimate for the time to implement this change was a period of two to three years.
676. The witness identified three principal transmission alternatives that had been assessed in detail against the proposed grid upgrade as: 220 kV into Pakuranga and Otahuhu; augmentation of the existing 220-kV assets by duplexing the OTA-WHK A and B lines, followed by a high-capacity double-circuit line from Whakamaru to South Auckland and 220-kV cables from South Auckland and Otahuhu; and augmentation of the existing 220-kV assets by replacing the conventional conductors on the OTA-WHK A, B and C lines with high-temperature conductors followed by a high-capacity line from Whakamaru to South Auckland, and 220-kV cables from South Auckland and Otahuhu.
677. Mr Boyle gave evidence that duplexing increases the mechanical loading on the towers, so strengthening of both the towers and the foundations will often be needed.
678. An additional factor taken into account by Transpower is transmission losses resulting from the resistance of conductors. Mr Boyle gave evidence about the way these losses would be increased or reduced by changes in the levels of current and voltage, including comparing the losses of the four options considered.
679. Mr Boyle gave his opinion that demand would exceed the supply capacity after the winter of 2013, and that doing nothing is not an option. His evidence was that, although all four options would enable the transmission of the large renewable potential south of Whakamaru to the upper North Island, the 400-kV-capable line had been designed to optimise the trade-off between costs, benefits and environmental impacts, including optimising the number of transmission corridors required for the grid in the future. It was his evidence that it is the option with the lowest overall economic cost, the lowest transmission losses, and one that would ensure the lowest number of transmission corridors required for the grid.
Submitters
680. Submissions in support identified the need for the 400-kV-capable upgrade to provide security and certainty of supply, as well as facilitating the increased use of renewable energy.
681. Submissions in opposition included the following themes:
682. There is no need for more overhead lines because Auckland needs to save power, not demand more.
683. The need for this line to be built is based on out-of-date and inaccurately high demand-growth forecasts (2005 SOO).
684. The demand-growth projections of the Electricity Commission (2007 SOO) do not justify its construction.
685. The scale and capacity of this proposed 400-kV-capable line is completely out of alignment with the expected requirements for transmission capacity into Auckland to meet the demand growth in the next 40 years.
686. Better equal-benefit alternatives to this proposed line are available that have a much reduced environmental impact.
687. The potential new-generation capacity likely to be constructed in the Auckland region in the next 40 years has been grossly underestimated in an attempt to justify this line as one of national significance and urgency.
688. Mr Freke argued to the general effect that it is not reasonably necessary to achieve Transpower's objectives to construct a work (ie 400-kV-capable) that will not be fully required for 25 years, if at all.
Consideration
689. In considering this issue, the Board understands that it is distinct from comparison of transmission alternatives, on which its role is to assess the adequacy of the consideration of alternatives, not itself decide which is preferable.
690. The Board finds that Transpower is required to ensure the reliability of the transmission system, and that this resulted in it considering options (transmission and non-transmission) for ensuring the continued security and certainty of electricity supply to Auckland, Northland, and parts of Coromandel and Waikato.
691. The Board accepts the evidence of Messrs Coad, George and Boyle about reliance on the 2005 SOO and the draft 2007 SOO by Transpower and the Electricity Commission in its use of demand forecasts and generation scenarios against which the 400-kV-capable upgrade and other options were assessed.
692. The Board also accepts the evidence of Mr Boyle that the use of the draft 2007 SOO demand data may delay the need date by a year, and that the date of accessing additional capacity by changing the operating voltage to 400 kV may also change. The Board considers that, as with most medium- to long-term planning, there is uncertainty about when forecast events may take place, and accepts this does not automatically mean there is less need for the upgrade.
693. The capacity of the line was in issue, with some submitters asserting the line would have much more capacity than is needed.
694. The Board accepts the evidence of Messrs George and Boyle about the complexity of the power system and the requirement that it is operated to meet the N-1 security standard, and that capacity of a transmission line cannot be determined by simple calculations using the theoretical ratings of the individual components of the grid.
695. In his evidence Mr Freke stated he had considerable doubts as to whether it is reasonably necessary for Transpower to adopt an option (400 kV) that will not be fully required for 25 years, if at all. He was cross-examined by Transpower’s counsel on this point.
696. The Board accepts the evidence of Mr Boyle that transmission investments are long-lived assets and require a long-term planning perspective.
697. In the absence of expert contradictory evidence, the Board accepts Mr Boyle’s evidence in relation to the need to adopt a long-term planning perspective.
698. The Board also accepts his evidence with regard to longer-term benefits that larger capacity lines may provide, by avoiding multiple smaller lines, and being able to release additional capacity quickly by changing the operating voltage to 400 kV.
699. The Board was given evidence about the 400-kV-capable upgrade being subject to the Electricity Commission’s GIT and that this had involved a comparison with other options. The Board accepts that the Electricity Commission’s approval of the 400-kV-capable upgrade indicates that the capacity of the line is not unreasonably greater than it needs to be to meet the objectives of the work.
700. The Board is not persuaded by those submitters who consider the capacity of the new 400-kV-capable transmission link is greater than necessary.
Conclusion on whether the work is reasonably necessary
701. The Board accepts Transpower’s submissions and the evidence of Messrs Coad, George and Boyle on the necessity for the work; and finds that it is reasonably necessary for achieving Transpower’s objectives.
Is the designation method reasonably necessary?
702. The Board has also to consider whether the proposed designation, as a planning method, is reasonably necessary for achieving Transpower’s objectives.
703. Transpower submitted that designation is the preferable planning method in that it signals the potential for future changes on the designation alignment; provides an established method for those changes to occur; provides a uniform approach through the various territorial authority districts; and in that it is not otherwise possible to freeze the existing position in respect of plan provisions. In particular, Transpower argued that a designation enables restriction on conflicting activities of the corridor over the period in which other resource consents are obtained, detailed design work done, and the work constructed, as the project is long term in nature and some of the works are not intended to be completed for a considerable time.
704. There was no substantial challenge by any submitter to Transpower’s submissions on this topic.
Evidence
705. In this respect, Ms Allan gave her opinion in evidence that designation is the most appropriate mechanism for Transpower to use in terms of the RMA, and that it would enable consistency of environmental standards and conditions across the length of the line.
706. In rebuttal evidence, this witness stated that a designation is a specific instrument provided for by the RMA to address projects proposed by network utility operators who are requiring authorities, and follows a specific process, with specific matters to be taken into account in decisions.
Consideration
707. The Board accepts Transpower’s submissions and Ms Allan’s evidence on this topic; and finds that as a planning method, the proposed designations are reasonably necessary for achieving Transpower’s objectives.
The width of the designations
708. As mentioned in Chapter 7, some submitters asked for a narrower designation, on a perception that farming practices would be less affected. Others sought a wider designation in forestry areas, or on a perception of risk of health effects, of risk of tower collapse, or of risk of trees falling on the line.
709. At least the requests for narrower designations raise the question whether the designations at the widths required by Transpower are reasonably necessary for achieving Transpower’s objectives. Rather than addressing separately the contentions that the designations should be wider than proposed, the Board considers together all challenges to the proposed widths of the designations.
Evidence
Transpower
710. Mr D J Campbell gave evidence that in planning the original proposal, Transpower had considered a range of factors that influenced the minimum width of the easement: electrical and magnetic fields, radio-frequency interference, audible noise from the line, and conductor swing (blow-out due to wind). The witness reported the determining factor at that stage had been a width that would control the audible noise from the line in conditions of potential corona discharge (during fog or rain) to a limit of 45 dBA at the edge of the easement. To achieve that, a design easement width of 65 metres (m) had been set to allow 32.5 metres on either side of the centreline.
711. The amended proposal would have a different configuration of conductors than the original proposal, and Mr Campbell explained that this would result in reduced noise levels at the edge of the easement. Instead, conductor swing became the critical factor determining the easement width.
712. In cross-examination Mr Campbell explained that the distance between towers (the span) would dictate the extent to which the conductors would swing, which would, in turn, dictate the width of the easement, as within that width the effects of electrical and magnetic fields, audible noise, and radio-frequency interference would be contained.4 He also explained that if a span increases due to moving a tower site, the designation width would increase marginally.5
713. In his evidence, Mr R G Lake described the detailed design basis for calculating the extent of conductor swing, depending (among many others) on the shape of the underlying terrain; the designs and configurations of the towers; the mechanical tension of the conductors; the range of operating temperatures; and the likely range of wind loadings. This witness described Transpower’s practice of defining an easement that is wide enough to fully contain the conductors under all loading and weather conditions, as well as accommodating operational and maintenance activities.
714. In his second rebuttal evidence Mr Lake described how clearance of the conductors in relation to all ground (including sloping ground) and above-ground points, such as trees, within the designated corridor had been checked, and would be re-checked as detailed design is undertaken. He told the Board the proposed designation width includes a five-metre construction tolerance on either side.6
715. So to allow for conductor swing, Transpower is seeking designations of a minimum width of 65 metres, but where line swing dictates, greater width than that; and, in plantation forest, approximately 100 metres or even 130 metres, depending on tree heights. Within the designation width, structures would be excluded, and there would be a limit on the height of vegetation.
Submitters
716. A number of submitters questioned the need for a designation width of as much as 65 metres. For instance, Mr N Fuller understood that the width would be 60 metres, and contended that a designation across their property of 120 metres would represent a significant amount of mature pine trees that would need to be removed.
717. Other submitters sought wider designations on two grounds: that 65 metres would not be wide enough to avoid the risk of trees outside the designation falling and striking the conductors, of toppling towers, of pre-existing activities generating smoke or dust impairing the functioning of the line; and that 65 metres would not be enough to protect people (especially children) living near the line from increased risk of developing certain disorders.
718. Those in the first group included the Mayor of the Franklin District (Mr M Ball), Mr D A Parker, Mr J Sexton, and Mr J E Scott (who also considered that the easement widths would be inadequate for dealing with materials, design and construction mishaps). Mr Sexton nominated a preferred width of at least 100 metres.
719. Those relying on increased risk of health effects included Drs Bennet, McQueen, and R Smart, urologist and member of NEE Health Committee, and Mr Davidson. The theme of their submissions was that the designations should be at least 600-metres wide, or 120-metres wide in the case of Mr Davidson, based on some epidemiological studies.
720. Mr Freke gave his opinion that the extent of the proposed easement should be increased to more properly reflect the actual zone of direct effects in terms of future limitations on land use. Asked in cross-examination whether the Board has jurisdiction to tell Transpower not to impose easement restrictions beyond the corridor, Mr Freke replied that if Transpower intends to do so, that should be very clearly articulated so the Board can take them into account, and potentially impose a condition that it does not seek to impose restrictions beyond the designation.7
721. On behalf of Carter Holt Harvey Limited (CHHL) and Hancock Forest Management (NZ) Ltd (HFML) respectively, Mr M Parrish8 and Ms Strang9 expressed themselves satisfied with Transpower’s offer to increase the width of the designation to 130 metres through the lands they are interested in, although with reservations about potential liability. As any liability question is a private property question for resolution in negotiations over easements, not a public law question for resolution in deciding on Transpower’s requirement for a designation, the Board is content with those indications that those submitters raised no relevant opposition to the widening of the relevant stretch of the designation.
Consideration
722. The effect of a designation is to exempt a requiring authority’s work from the land-use control created by section 9(1) of the RMA, and to prohibit (without the requiring authority’s consent) certain activities on the designated land that would prevent or hinder that work.10 It does not, itself, entitle the requiring authority to infringe private property rights of others in land.
723. The width of the designation might be used by landowners and Transpower as a starting point in negotiations over the extent of an easement that might be granted for the line. However, the parties would be free to reach agreement on an easement of a greater extent than that of the designation. The effect of the designation, and a territorial authority’s consideration of a requirement for it, relates only to the extent of the designation.
724. The Board accepts the validity of Transpower’s practice of seeking designations wide enough to contain the lines and towers, including the extent to which the conductors would swing under wind forces under all loading and weather conditions, as well as accommodating operational and maintenance activities, and a five-metre construction tolerance on either side.11 There was no substantial challenge to Transpower’s contention that this requires a total designation width of at least 65 metres. The extent to which there might be noise, radio, television and electronic interference perceived beyond the edges of a designation of at least 65-metres wide is addressed in Chapter 11 of this report.
725. To the extent that Transpower might wish to limit activities on land beyond the extent of a designation (other than any restrictions that might otherwise be imposed by law), it would need to acquire from the owner of the land in question property rights, perhaps by easement,12 or by covenant, to that effect. That is a private matter, and is beyond the scope of a territorial authority’s jurisdiction in considering a requirement for a designation.
726. However, persuasive Mr Freke’s concerns in the public interest, the Board holds that it is beyond the power of a territorial authority considering a requirement to impose conditions on a designation to limit the freedom of requiring authorities and landowners to reach their own agreements about the terms on which easements or covenants concerning activities on land outside a designation might be granted or undertaken.
727. In Chapter 9 of this report, the Board addresses the concern of some submitters about the risk of certain disorders arising from dwelling near high-voltage transmission lines. The Board concludes that there is no basis for finding that people living more than 32.5 metres from the proposed centre line would be exposed to such a risk from the electric and magnetic fields around the conductors. Therefore, that concern, shared by a number of submitters, does not justify the Board determining that it is reasonably necessary for achieving Transpower’s objectives that the designations should be wider than proposed, let alone 600-metres wide.
728. That leaves the risk of a transmission tower toppling and falling onto land beyond the extent of the designation. In his evidence, Mr Lake explained that the designation width is not designed to accommodate the extreme scenario of matching the overall height of a tower in a tower failure situation.
729. On Mr Lake’s evidence about the design and testing of tower structures and foundations in accordance with internationally accepted practice, the Board finds that the probability of a tower toppling is so remote that it would be disproportionate to make provision for the contingency. Further, such an event is not included in the intended activity for which the designation is required. The Board does not accept that it is reasonably necessary for achieving Transpower’s objectives to widen the designations on that account.
730. There was no contest over the width of the designation for underground cables.
Conclusion on widths of designations
731. Having considered the questions raised about the widths of the designations, the Board finds that widths no less than 65 metres are reasonably necessary for achieving Transpower’s objectives; that widths up to 130 metres are reasonably necessary for sections of designations that pass through plantation forests; and, apart from that, there is no relevant basis for designations to be wider than required to accommodate conductor swing, necessary operational and maintenance activities, and construction tolerances.
Conclusion on necessity for achieving objectives
732. In conclusion, the Board finds that the proposed works and designations are reasonably necessary for achieving Transpower’s objectives, for which the designations are sought.
Endnotes
1. Transcript 27/03/08, p 36.
2. Transcript 1/04/08, p 12.
3. Transcript 2/04/08, p 19.
4. Transcript 3/04/08, pp 45f.
5. Transcript 3/04/08, p 47.
6. Transcript 10/04/08, p 37.
7. Transcript 11/09/08, p 8.
8. Transcript 7/10/08, p 41.
9. Transcript 7/10/08, p 50.
10. RMA, s176(2).
11. Transcript 10/04/08, p 37.
12. See Gale, 2002, paras 1-37–1-45.
