At ARBS 2018, Australia’s most important HVAC&R and building services exhibition, CO2 heat pumps were all the rage.

Suppliers like Mayekawa, Mitsubishi Heavy Industries Air-Conditioners Australia, and Automatic Heating Global all had CO2 heat pumps on display — and all remarked that interest in the technology was increasing from businesses looking to move away from gas-fired boiler systems. (The situation is similar in the U.S.; see “NatRef Heat Pumps: A Key Piece in a Decarbonized Future,” Accelerate America, April-May 2019.)

One year and several installations later, suppliers have gained confidence that the technology has real commercial potential in a number of different sectors and applications.

Two case studies — at a winery and a small hotel — presented during the ATMOsphere Australia 2019 conference in May helped paint a picture of the businesses and applications where CO2 air-to-water heat pumps have the most potential in the Australian market.

Free Space Heating and Hot Water

Halfway between Sydney and Brisbane is a city named Armidale, New South Wales.

Here temperatures often drop below -5°C (23°F) on winter nights due to the city’s high elevation (1,110 m/3,641 ft) above sea level.

So for hotel owners in the area, a frequent question is, “Are the rooms heated?” In the FAQ section on City Centre Motor Inn’s website, the answer is an emphatic “Absolutely!”

“We know how to keep the rooms warm,” the website states.

Not only does City Centre Motor Inn — a small family owned motel catering to tourists — know how to do this, but it has done so in a carbon-neutral way through the use of solar energy and CO2 heat pumps.

In February, the hotel installed 30 kW of solar PV panels on the roof and connected it to a single Q-ton CO2 air-to-water heat pump supplied by Mitsubishi Heavy Industries Air Conditioners Australia (MHIAA).

At the ATMOsphere Australia 2019 conference, Trent Miller MHIAA’s Air-to-Water Manager, illustrated how the configuration has resulted in essentially free hot water and space heating for the hotel. The Q-ton, he explained, runs for about two hours per day, generating 2,000 l (528 gal) of hot water storage, about 1,000 l (264 gal) more than necessary; the excess serves as thermal storage. “So essentially now, whenever the PV is running, the Q-ton comes on first, then all the air conditioning comes on,” said Miller. “Basically they’ve got no power bills.” The payback period on the cost of the installation for the end user, he added, is about two-to-three years.

With solar PV technology continuing to rapidly develop, Miller sees hot-water heating headed in this direction — where all that is needed is a highly efficient piece of equipment running purely off solar energy. In fact, Miller said, “one of the people that resells our [Q-ton CO2 heat pumps] used to be the largest commercial retailer of t hermal solar systems.”

The application has significant potential, Miller said, when scaled up to facilities such as large hotels and residential complexes. “There’s big movement towards this within the industry now.”

Winery Saves 75% on Energy Costs

In January 2019, the Brown Brothers Milawa Winery — an Australian family-owned business located in central Victoria — decided to install a CO2 heat pump to supply hot water for rinsing its wine filtration systems.

Originally, Brown Brothers used a liquid petroleum (LP) gas hot water boiler system, which cost $13 per 1,000 l (264 gal) of hot water, said Terry Plaisted, national sales manager for Automatic Heating Global, a Melbourne-based hot-water heating solutions provider that supplied the CO2 heat pump to the winery.

With LP gas boilers known to run at low efficiencies compared to heat pumps, Automatic Heating Global showed the winery that it would cut its energy costs to $2.70 per 1,000 l of hot water using a CO2 air-to-water heat pump with a coefficient of performance (COP) of 3.6.

“Saving 75% on energy costs, along with the elimination of the need for LP gas, is, as they say, a ‘no-brainer,’” said Plaisted.

The CO2 heat pump at the winery is manufactured by Japanese OEM Nihon Itomic Co., Ltd., and sold and installed in Australia by Automatic Heating Global, which unveiled the system in Australia at the ARBS exhibition in May 2018.

According to Plaisted, interest in CO2 heat pumps is not slowing down. The company is continuing to pursue opportunities in the winery sector, as well as in food processing and in residential and commercial hot-water heating applications.

In August 2018, the company installed a CO2 hot-water heat pump at a residential apartment building in Melbourne’s central business district.

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