A powerful adventure

The High Voltage Direct Current (HVDC) inter-island link is a key part of New Zealand's National Grid - transporting bulk electricity between the North and South Islands. The HVDC is 645 km long, and runs from Benmore Hydroelectric Power Station in Canterbury to Haywards Substation in Lower Hutt. It includes 40 km of submarine cables between the South Island and the North Island. The HVDC is owned and operated by Transpower, where I work.

When I returned home from my big journey by bicycle from New Zealand to Denmark, I was a little worried about the "trail blues". Getting up on Monday mornings, cycling to the Transpower office in the rain and sitting by a computer all day could easily suck the joy out of the adventurous life I had got used to.

However, it didn't take long before I came up with a mad idea for a great adventure in my own backyard: Cycling the length of the HVDC line!! The craziest thing was that people wanted to join me, so on a beautiful sunny morning in April, four of us set off from Haywards Substation in the direction of Benmore.

Haywards Substation

The planning was not easy. Permission to cross private land had to be obtained, a difficult route had to be planned, but my lovely Transpower colleagues were very excited, helpful and supportive.

It wasn’t all smooth cycling! There was plenty of “type 2 fun” (activities that are not enjoyable during the experience but are fun to recall and reflect upon afterward). We organised the weather well – except for the cyclone! The Waipara River was swollen, so we couldn’t ford it with our bikes but had to detour out to the less pleasant State Highway 1 bridge to cross this river. I also recall starting with wet shoes on a cold Canterbury morning in 1˚c, where you lose feeling of your toes, or fixing a flat tyre in the rain. It certainly makes one wonder why we are doing this??! Or pushing your bike up a very, very steep gravel road in the dark or getting grumpy or “hangry” with each other because of circumstances beyond our control. We also ended up walking into Omarama Pub during a Highlander vs Crusader match... To top it all off, Air NZ cancelled our flight home, as we were on our way to the airport with our bikes, so my colleague and I ended up having an unplanned workday with the friendly people in the Transpower Christchurch office.

However, the challenges were far outweighed by the many, many highlights:

• Cycling through some of NZ most stunning back country with the autumn colours splattered like a beautiful painting.

• Crossing private land, where very few people and cyclists ever venture.

• Enjoying beautiful sunsets, starry nights, and crisp, sunny days.

• Enjoying deep friendships and making new friends.

• Staying in lots of different accommodations: Transpower houses, tenting, cabins, motels, hotel and private home.

• Eating lots of chocolate, great pies and sampling local beer.

• Having too much birthday cake and being able to eat it all (I had a great birthday while on the trip).

• Selfies with lots of towers (pylons), including tower 1000.

• Counting down from tower 1621 to tower 1 and “suffering tower withdrawal symptoms”, when the route got a bit too far away from the line.

• And then there are all the things that makes me smile and laugh now but will forever be an inside joke for the select few who understand and were part of the adventure.

The HVDC behind Wellington

Oteranga Bay and the submarine cable landing station

Hodder Bridge on Molesworth

Isolated Flats on Molesworth

Cycling across Isolated Flat

Tower 1000

Tower 532 and Mt Hutt

Cold morning at Mayfield

Tower 30

I also enjoyed learning more about our electricity grid, its history and the importance of the HVDC. The HVDC was commissioned in April 1965, and personally, I can’t think of a better way of celebrating a key piece of New Zealand infrastructure than cycling along it sixty years later.

Back in the 1950s there was discussion of a nuclear powerplant north of Auckland to meet the increase in power consumption in Auckland and the North Island. However, instead the Huntly coal deposit was discovered and the HVDC was commissioned. Throughout the 1960s and 1970s, the New Zealand anti-nuclear movement gained momentum, fuelled by concerns about nuclear weapons and testing. This culminated in 1984 when the government declared New Zealand a nuclear-free zone.

It is interesting to ponder the unknown value the decision makers, engineers and others created back in the 50s and 60s. It makes me question if we are investing enough in our future and leaving future generations with valuable assets for a better life and a better world?

The HVDC link is a vital part of New Zealand’s power system today. It is becoming more critical given the dependence on the growing intermittent wind and solar generation when sun and wind drops away. While we were cycling, the direction of the power along the line switched many times depending on the generation of solar, wind, geothermal and thermal power in the North Island and hydro in the South Island. You can at any time see the percentage of renewable energy in NZ on the Transpower website.

The HVDC link is going to be key in enabling New Zealand’s goal of achieving net zero carbon by 2050. Transpower expect electricity use to increase by almost 70% by 2050 as we switch to electric transport and electric commercial process heating. There are more thoughts on the HVDC future here and the future of electrification on the Transpower website. Hence, Transpower has recently secured global cable solutions supplier Prysmian to replace the HVDC submarine electricity cables in 2032 at a cost around NZ$450m.

First glimpse of Lake Benmore

To finish, I'm very grateful for all the help, food and accommodation we received along the way from strangers, friends and colleagues. A special thanks to the private landowners, who allowed us to cross their land. These landowners deserve a huge thank you from us all for having the HVDC line through their land over the last six decades. New Zealand would be a different place if it wasn’t for the HVDC and my life would certainly be less adventurous!

Finally, the stats:

• Kilometres cycled in total along the line: 845km

• Kilometres cycled in total on the whole trip (including to the ferry etc): 940km

• Longest day: 118.3km

• Total number of days cycled: 11

• Elevation climbed: 9,590m

• Highest point: 1,145m (Ward Pass)

• Flat tyres: 4

• Rainy days: 5

• Pie consumption: Not to be disclosed (however, we can reveal that the best pies are in Darfield)

• Power transferred along the HVDC during our cycling journey: 51 GWh was sent south and 12 GWh was sent north (this is a bit unusual, because the flow is predominantly south to north, but the generation mix had lots of wind and thermal generation from the North Island).