K&L Nurseries uses energy efficient technology to help grow flowers and shrink costs

Casestudytile KLNurseries 001 SL B 201508 Open

An innovative energy efficiency project has transformed a family business into a sustainable energy trailblazer. K&L Nurseries is a proudly local business with a heritage in horticulture dating back to the early 1900s.


From its base in Christchurch the company grows over 70% of the South Island’s supply of gerberas, but that requires energy - lots of energy - to heat the nursery’s 0.8 hectares of glasshouses.

However by 2010, with K&L seeking to double its energy load from 1 MW to 2MW to support expansion and provide extra heat for its glasshouses, the nursery was facing its own energy crisis.

Energy equations

K&L generated its heating by burning coal in an aging two-boiler system. Both boilers required a lot of maintenance and an expensive rebuild, potentially costing $100,000 was looming.

Worse, even then the very best energy efficiency that could be expected was 60% to 65%. With projections showing the company would need to burn 1000 tonnes of coal a year, that meant up to 400 tonnes of expensive fuel was going straight up the chimney as waste.

It was also hard to buy good quality coal and, especially after the closure of the Pike River mine, that sometimes forced K&L to burn lower grade fuel.

There was another wildcard in nursery’s energy equation, the Emissions Trading Scheme. While the carbon tax was capped at $12.50 a tonne, if the cap were removed, carbon costs could have gone as high as $50 a tonne.

Limited options

If K&L had been in the North Island, gas could have solved its problem. Electricity was out of the question because of cost. Other potential solutions such as a deep aquifer heat pump required too much capital.

Instead, Kempthorne found himself looking to wood as a boiler fuel. While some had converted coal boilers to wood, dedicated biomass technology developed in Europe appeared much more promising, delivering outstanding efficiency with almost no unburnt carbon and flexible fuel options.

Further research, including a trip to Europe, showed only one provider, Austrian company Polytechnik, could support an installation in New Zealand, through its Palmerston North-based agent Energy Plant Solutions.

Green light

K&L also had specific needs that Polytechnik and Energy Plant Solutions were prepared to address. They were willing to help integrate a thermal store tank, for instance, that allowed the boiler size to be reduced by 60%.

The fuel handling system and furnace design also delivered real fuel flexibility, handling fuel of varying sizes and efficiently drying fuel with high moisture content. That would in time allow K&L to burn its own waste material and that of local arborists, further cutting fuel costs.

An EECA grant and backing from the nursery’s bank allowed K&L to green-light the project.

Innovation focus

In its first year, K&L calculates it saved $56,000 thanks to its new boiler. However, six months of that involved operating without a thermal tank that allowed the boilers to operate continuously.

The store tank design was one of the most innovative parts of the project. K&L had seen underground tanks inside Dutch glasshouses but the manufacturer could not deliver in New Zealand.

With the help of Energy Plant Solutions, the nursery installed one itself at only a third of the cost of an above-ground steel tank, and far more efficient. The underground system meant the tank did not require a pad or expensive earthquake engineering.

The tank allowed the boiler to be downsized to about 60% of maximum load continuously, making it even more efficient.

Great results

K&L has achieved its primary aims. Since commissioning its new boiler in June 2013, the nursery had more heat than ever for its glasshouses at much lower cost. The business is now saving $115,000 a year and achieving more and better flower growth.

The boilers are also far easier and safer to maintain and operate than the old coal technology. In fact, Polytechnik tunes and monitors the boiler over the internet from Austria.

But a series of less expected benefits are also flowing from the company’s $820,000 investment.

In addition to the marketing boon of being a sustainable environmentally friendly company, eliminating coal has cut waste disposal costs because wood ash can be used as fertilizer.

Burning coal also over time stained the glasshouses, reducing light needed for winter growth.

Around a hundred tonnes of K&L’s own plant trimmings and coconut fibre growing material are now used as clean, efficient fuel rather than being dumped or burnt in the open air. Extra heat has even helped K&L to control humidity in its glasshouses, eliminating the use of fungicides.

Even the neighbours are happy, saying they no longer have ash on their washing or smell gas from the old coal boiler.

Company profile

K&L Nurseries is a family-run flower growing operation in Christchurch with a family history in the industry dating back to a Great-Grandfather, who grew freesias and table grapes in Dunedin in the early 1900s.

Specialising in Gerberas and Roses, K&L Nurseries produces more than 2 million stems of cut flowers per year, selling them through wholesale auction houses and distributing them to retail clients across the South Island.

K&L Nurseries won top honours in the 2014 EECA Awards, for a New Zealand-first bioenergy project and the Small to Medium Business Award.

Key benefits

  • The new biomass boiler and thermal tank have delivered $117,000 a year in cost savings.
  • Waste biomass is now used as fuel and plans are afoot to expand waste biomass collection in the nursery’s area, reducing the need to purchase wood for fuel.
  • K&L Nurseries is now a trailblazer in biomass energy generation and a reference site for other businesses considering a change.
  • Noxious emissions have been slashed, increasing productivity in the glasshouses and improving the local environment.

Key features

  • A customised 900kw biomass boiler replaced two aging coal boilers.
  • An innovative underground thermal store tank has further increased energy efficiency.
  • The installation is being managed and monitored over the internet


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