From out of the clouds comes money, if you’re an airport, and energy, if you’re a solar panel. Owners of air terminals who put one with the other are on to a good thing. Adelaide Airport’s 1.17MW system and Darwin Airport’s 4MW conversion are testament to that, without mentioning other successful applications around the world.

Up in Queensland, where it’s sunny almost all the time, Brisbane Airport Corporation had been toying with the idea of sourcing some of its electricity from solar generation for three years but the cost of panels and the predicted output conspired to make it commercially unviable. Over time, those constraints relaxed. Panels became cheaper and ever more efficient, and – the last piece in the puzzle – the cost of electricity increased and increased.

“A combination of all three made it viable,” says Brisbane Airport Corporation general manager assets Krishan Tangri.

The solution is a 6MW system across six sites.

The Queensland capital’s airport has a sister relationship with Amsterdam’s Schiphol Airport, which lent some intelligence in developing a strategy and to confirm assumptions made by Tangri’s team. Renewable energy projects at Adelaide and Darwin airports were also analysed for likely challenges or tips on how to get it right.

“We knew that it was possible to do it in Australia, the question was: What price?” he says, quickly reminding EcoGeneration that a solar upgrade would also fit the airport’s strategy to pursue any improvements to operations that cut emissions. “Using renewable resources is part of that environmental strategy,” he says, where the community is satisfied by a reduction in the carbon footprint and shareholders are satisfied by cuts to operating cost and an increase in profit.

The design

Brisbane Airport operates all hours but Tangri describes the load profile as a typical bell curve, peaking around midday. Usage peaks in the summer as air-conditioning units slave to keep the travellers and workers comfortable. Over the past few years a drive to find efficiencies has seen electricity use cut by about 8GWh a year aggregated across about 40 projects, he says. During this time about $200 million a year was spent on expansion at the airport over five years. It ended up being a perfect match of give and take, he says, where efficiencies offset emissions.

“In spite of all [the spend on expansion], the carbon footprint hasn’t increased,” he says. “Through the efficiencies initiative we have been able to achieve carbon-neutral growth of the airport over the past five years.”

Over the past 10 years passenger traffic at Brisbane Airport has increased from 17.4 million to 22.9 million.

Room for growth

The airport’s new solar system will be spread over six sites: five roof-mounted, with a total of 5MW, and one ground-mounted, about 1MW. The biggest stage, a 1.9MW array atop the international terminal, will probably be the largest roof-mounted system in the Southern Hemisphere, he says.

Construction is about to begin, as soon as negotiations are concluded with South-East Queensland distribution network Energex. Design and construction company Epho won the tender and total cost is around $11 million, Tangri says, with recovery in lower electricity bills estimated at $1 million a year.

No grants or subsidies were relied on, other than Large-scale Generation Certificates. The team tested the project’s net present value without the benefit of LGCs out to 2030 and found it was still viable. “There is no certainty LGCs will stay on until 2030 so we wanted to see whether it would still stack up, and we were fortunate that it did.”

The airport has three arrangements with Energex, whose concern so far Tangri says is around whether the system will export. That’s doubtful. “Because we are using all the energy generated ourselves they are relatively comfortable.”

He says about 18% of the airport’s electricity will be supplied from the solar PV system and about 6% of Brisbane Airport Corporation’s overall load, where the corporation’s use includes an embedded system that supplies tenants.

Not fully charged

It’s a risk to rely too much on intermittent generation at an infrastructure site where humans are held aloft in speeding aircraft. “We have critical infrastructure,” he says. “We have to look at the optimum mix of renewables and non-renewables.” Other considerations were voltage fluctuations and glare that may affect navigation.

The 6MW target is defined by a cap imposed by the airport’s electricity provider, and Tangri says negotiations may transpire around increasing the size of the ground-mounted stage to lift the total output to 10MW. The contract ends in 2019, and by then everyone knows solar technology will be even cheaper. (Epho is using Trina modules and ABB inverters.)

What with the load far exceeding generation from the proposed solar PV system it seems there wouldn’t be much requirement for storage, and on Tangri’s calculations of payback for storage of between 50 and 90 years the technology would have to become far, far cheaper before it was considered.

“It doesn’t stack up,” he says. “We are waiting for the cost to come down.” And he is confident that will happen.