Airports are pretty fussy neighbors. You can’t put up anything tall near the end of a runway, and if you want to build something shiny next to one, you’d better be able to explain why it won’t dazzle a pilot on the way in.<\/p>\n
So a solar farm right behind the runways of New Zealand’s second-busiest airport was always going to be a bit complicated. Christchurch Airport went ahead and hosted one anyway. It’s called K\u014dwhai Park, and it’s now the biggest solar farm on the country’s South Island.<\/p>\n
Prime Minister Christopher Luxon officially opened it on October 15<\/a>, but the farm’s actually been running for a couple of months. It went live in August, and The Press, Christchurch’s daily paper, reports it’s been gradually sending more electricity into the national grid ever since. I haven’t seen a figure for what it’s producing right now, just that the number’s been going up.<\/p>\n Getting the power out took some doing. It meant burying a high-voltage cable, and according to Ventia<\/a>, the contractor that built the grid connection, the underground cable work had to happen late at night, when no aircraft were operating. Each night, the crew dug a stretch of trench, laid ducting in it and filled the whole thing back in before the airport got going again in the morning.<\/p>\n Ducting’s basically a run of pipe that goes into the ground first. The cable gets pulled through it later. Kalim Guthrie, who’s managing the job for Ventia, said the crew had to stay on schedule because “the disruption to the airport would be huge otherwise.”<\/p>\n Frankly, that sounds like a pretty miserable way to lay cable. It’s the same logic that has highway crews repaving at 2 a.m., just with jets instead of rush-hour traffic.<\/p>\n And it’s a very different approach from the one used in Paris, where a tunnel boring machine spent 19 months grinding under two runways<\/a> at the city’s main airport while planes kept landing overhead. The contractor’s write-up doesn’t say how many nights all that took, or exactly which parts of the route ran close enough to the airfield to need the night shift.<\/p>\n The farm’s own electrical system works at 33,000 volts. According to Ventia, a substation on Pound Road steps that up to 66,000 volts and sends it through the buried cable to a second substation on Grays Road, which drops it to 33,000 volts again. That second one’s where the airport and Orion, the company that runs the local power lines, will eventually hook in.<\/p>\n So why double the voltage just to cut it in half again? Pushing the same amount of power at a higher voltage means less current flowing through the wire. Less current means less energy wasted as heat along the way, and long-distance power lines run at very high voltages for exactly that reason.<\/p>\n Keeping the farm right next to the airport helps with losses too. The airport’s FAQ<\/a> argues that making the electricity beside the airfield wastes a lot less of it than generating it somewhere far away and shipping it in.<\/p>\n The run used about 10.5 miles of cable laid in roughly 2.8 miles of trench, according to Ventia, which also designed and built both substations. I’d guess that’s mostly because high-voltage lines like this usually run as three separate cables, one for each phase, but the company doesn’t break it down.<\/p>\n The solar farm covers 568 acres on the west side of the airfield, and its panel count comes to around 300,000, according to the airport. Part of that ground belongs to Environment Canterbury, the regional council, which leases it to the airport. Technically, K\u014dwhai Park is the name of a 988-acre energy park the airport has set aside, and the solar farm is just its first phase.<\/p>\n You’ll see two capacity figures for it, 150 megawatts and 168 megawatts, and they’re both right. Solar panels make direct current, while the grid runs on alternating current, so everything has to pass through inverters first.<\/p>\n The 168 is what the panels are rated for, and the 150 is the most the farm can actually send out at once. Over a full year, the airport expects the farm to make 275 gigawatt-hours, which it says is about what 36,000 homes use in a year.<\/p>\n It’s a fair question. It’s even in the airport’s FAQ. The airport’s answer is that solar panels are built to soak up light rather than bounce it back, and before construction started, it said it was running technical studies and talking to aviation groups to confirm the project was safe.<\/p>\n Which makes a fair bit of sense if you think about it. A solar panel that bounced a lot of sunlight back at the sky would be a fairly lousy solar panel.<\/p>\n I couldn’t find the results of those studies published anywhere. But the FAQ also lists airports that already have solar arrays nearby, including three in the US: Denver, San Francisco and San Diego. We’ve covered a couple of European examples too, like Frankfurt’s upright panels along a runway<\/a> and the raised panels beside Berlin’s airport<\/a>, where corn is banned underneath because it attracts birds.<\/p>\n Synlait, a New Zealand dairy company, will buy 25% of K\u014dwhai Park’s electricity to run its Dunsandel and Dairyworks sites, and the airport is buying power from the farm as well. Both deals are long-term power purchase agreements.<\/p>\n That’s basically a contract to buy a set share of a plant’s output for years at a time, so the owners know someone’s paying for what they generate. So the airport gets power from a farm right next to its runways, and the farm gets a customer that isn’t going anywhere.<\/p>\n Contact Energy, one of New Zealand’s big power companies, owns the farm 50\/50 with international solar developer Lightsource bp. The airport puts the price at NZ$273 million, or somewhere around $160 million. At the peak of construction, 235 people were working on it.<\/p>\n The airport itself is publicly owned. Christchurch’s city council holds 75% of it through a holding company, and the national government owns the other 25%, according to New Zealand’s Treasury<\/a>. Contact chief executive Mike Fuge said in the airport’s October 15 opening announcement that K\u014dwhai Park is the company’s first finished solar farm, and that it already has approval for two more with Lightsource bp, in Taranaki and Northland.<\/p>\n","protected":false},"excerpt":{"rendered":" Airports are pretty fussy neighbors. You can’t put up anything tall near the end of a runway, and if you … <\/p>\nThe power goes up to 66,000 volts and back down again<\/h2>\n
So how big is it?<\/h2>\n
Won’t all those panels dazzle the pilots?<\/h2>\n
A dairy company is buying a quarter of the power<\/h2>\n