Page 27 - Climate Control News Magazine June 2019
P. 27

Boilers & Heating
Table B1.1 Comparative cost of heating 1 tonne of water from 40°C to 90°C
Cost of gas/electricity $12/GJ (4.3 c/kwh) 12 c/kwh
Required energy input (kWh)
Cost of heating 1T water by 50°C $3.14 $1.74
Saving with heat pump
for thousands of businesses across Australia. “We found many manufacturers could save money today simply by replacing their gas-fired boilers with industrial heat pumps. It’s just not
widely taken up yet,” he said.
“As the world transitions away from fossil fuels,
we will see most industrial processes becoming emissions free. Our report shows it’s possible now.” By switching to electrical heating it is possible to double the efficiency of many industrial pro-
cesses, according to the report.
This greater efficiency is due to the ability of
electrical heating technologies to:
• Deliver heat at the precise temperature required
(traditionally, industrial heat is often provided
at temperatures well above what is needed);
• Transfer heat directly to a material, with very
little heat escaping to the environment;
• Provide heat at the point of use, minimising
distribution losses.
Heat pumps use electricity to make hot water, air or steam. They can produce several times more thermal energy than they use in electrical energy, leading to remarkable efficiencies of 300 to 700%.
Heat pumps also enable manufacturers to re- use sources of energy that are otherwise wasted, such as the heat expelled by refrigeration systems. Heat pumps save so much energy their installa- tion cost can often be paid back within two years.
The most exciting potential application for heat pumps is as an alternative to the inefficient cen- tralised gas boiler systems found in most factories.
The report also examines electromagnetic heat- ing technologies which can cut energy use in half.
Electromagnetic technologies are safer than gas-fired heating, more controllable and produce a more consistent output, the report said listing the benefits of infrared radiation, induction heating and dielectric heating.
“Electric resistance heating has huge potential as it is a simple alternative to most industrial
gas-fired heating systems. For example, elec- tric resistance boilers produce hot water or steam up to 220°C and could replace gas-fired boilers,” the report said.
tion, already run predominantly on electric re- sistance heating due to its greater controllability, lower maintenance and absence of emissions from combustion.”
A heat pump system costs around $500-1000 per kilowatt of heating capacity for heat pumps
with capacity below 500 kW, and around $275- 500 per kilowatt for systems of 1 MW and above, according to Beyond Zero Emissions.
The total cost might be two or even three times the up-front cost of an equivalent gas boiler,
however the heat pump can pay for itself in just a few years thanks to cheaper running costs. “Most heat pumps in use today supply temper- atures below 100°C. The efficiency, flexibility and reliability of heat pumps have improved consid-
erably in recent years,” the report said.
“Heat pumps are now available that can sup- ply steam or hot water up to 165°C, or hot air up to 120°C. Within a decade heat pump manufac- turers expect to commercialise industrial sys- tems capable of reaching 200°C. The heating ca- pacity of single modules is also growing, with
several available in the megawatt range.”
So far there are very few industrial heat pumps
installed in Australia.
Despite this heat pumps have huge potential
to replace gas and other fossil fuels in most pro-
cesses requiring hot air, water or steam up to about 160°C. They could provide most of the heat energy required by the food, paper, wood and textiles industries. The report estimates heat pumps could displace one third of the energy used by chemical sectors to generate steam.
In total heat pumps could eliminate the need for 95 GJ of fossil fuels used for industrial heat – 15% of the total. When powered by renewable en- ergy this would eliminate nearly 5 million tonnes of greenhouse gas emissions.
“This report promotes heat pumps that use re- frigerants with low global warming potential.
This includes natural refrigerants such as CO2, ammonia and water, as well as some newly- developed HFCs.”
Electrifying food preparation can halve the amount of energy required. This approach relies on electric heat pumps and infrared ovens, both of which are three times more efficient than the existing gas-fired systems.
The heat pumps recover the large amount of waste heat expelled from the refrigeration compressors, and operate with an average effective efficiency of 300% (a coefficient of performance of 3).
continued to next page
The upfront cost of a heat pump system is much higher than a gas boiler but it can pay for itself within a couple of years due to much lower running costs.
Gas boiler
(80% efficient)
Electric heat pump
(COP of 4)
"Some industries, such as carbon fibre produc-
JUNE 2019

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