Harnessing the power of the sun pays big dividend
South Auckland Forging Engineering Ltd (SAFE Ltd) had a problem – the cost of electricity was going only one way, and that was up. For a heavy forging plant, this is bad news. The solution, in the end, was the installation of solar panels, a 68kW solar array of 360 photovoltaic panels, groundmounted at a 30-degree angle for highest efficiency, with a maximum generation of 62.4kW. Six inverters change this electricity from DC to AC power required for SAFE Ltd’s heat treatment furnaces, forging plant and CNC machines. It is one of the largest solar power plants in New Zealand.
Now 70 percent of the electricity that SAFE. uses in year is generated on site. Not that the company gets to use all this energy as the plant is not a seven-day-a-week operation and power storage technology is not yet as cheap as it might be, so the surplus is fed back into the grid for which Meridian gives SAFE a credit, albeit a decreasing amount, says Richard Johnstone, somewhat wryly. “But it’s not about the money, really,” he says. “It’s about the environment. Engineering isn’t best known for being green – it’s an energy-hungry industry. But we can do our bit with new technologies coming along. I look forward to the day when storage becomes more efficient and cheaper. There are beginning to be moves in this area, technical advances are being made and the cost of batteries is coming down.”
SAFE operates a heavy forging plant, a large heat treatment facility, machine shop, metallurgical laboratory and training programme all on the one three-hectare site, to provide a “one stop shop” integrated manufacturing service. With drop-hammers and forging presses to 1200 tons, SAFE Ltd produces specialised, customised, high-integrity product for most industries in New Zealand. Innovation and capacity expansion is a continual development at SAFE Ltd, with a new process for Titanium forging and extrusion currently under construction.
SAFE did its sums on projected rather than historical usage because the company is largely project-driven which makes for a lot of variants. It wasn’t a huge outlay to go solar but not insignificant either, but the company immediately saw a return on the spend and the investment will definitely pay off – in droves when energy storage technology becomes more affordable, says Johnstone. The only blip in the future could be with line providers, who will find solar power users will be using the grid connectors less and will therefore want to pay less. Some legislation will have to be written around that, Johnstone reckons.