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The two most common sources of energy used in Australian food, grocers and liquor stores are electricity and gas (including piped natural gas and other forms of liquid and gaseous fuels e.g. LPG). There are options available to decrease your electricity and gas purchase and consumption by using alternative energy sources. In Section 2.3, we outlined the ‘green’ energy products offered by energy retailers, including green electricity (e.g. Greenpower) and green gas products. These products can be purchased directly from your energy retailer and can be used to reduce the overall environmental footprint and carbon emissions associated with the energy used by your business. The other alternatives include heat recovery, solar hot water and alternative electricity generation including solar and wind.
7.1 Heat recovery Waste heat can be recovered from your existing equipment (e.g. refrigeration compressors) to offset the need to produce heat yourself (e.g. with your HVAC system). Dependent on how you produce heat in your premises this will decrease your electricity or gas consumption. Waste heat is recovered using a heat exchanger which transfers the heat from one medium (e.g. air) to another (e.g. water). The opportunities to recover heat from your existing supermarket equipment are covered in detail in Section 4 of the Handbook. Examples of supermarket equipment that produces waste heat are: • Refrigeration systems e.g. compressors • HVAC cooling systems e.g. air conditioning compressors • Kitchen cooking equipment e.g. ovens. Waste heat can be used directly or it can be converted into electricity using a waste heat generator. However, this solution is unlikley to be commerically viable in supermarkets at this stage given that electricity prices in Australia, whilst rising, are still relatively low and waste heat found in supermarkets is generally low grade (low temperature) and in small volumes.
7.1.1 The business case A number of factors will go into determining the investment returns of recovering heat from your existing equipment: • The ‘grade’ (termperature) of heat that can be generated through heat recovery • The opportunities to use the recovered heat and the current cost to generate that heat • The capital cost of the heat recovery equipment including the heat exchanger together with the pipes and pumps to transfer the heat to where it is needed.
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7.2 Solar hot water Solar hot water systems were introduced in Section 4.4 of the Handbook as one of the systems that can be used to produce hot water for your supermarket. Solar hot water systems can be very energy efficient as they use free energy from the sun to do most of the heating thereby reducing the cost of creating hot water. Solar hot water systems use the sun to heat mains water by passing it through black tubes located in an area that is exposed to sunlight, normally on a roof (as shown in the photo). The water heated by the sun then stored in a tank ready for use. If the required water temperature is higher than the system can produce, using the sun’s energy, then an additional heating system is used to ‘top-up’ the temperature. This can be done using an electrical element in the storage tank or using an inline gas-fired hot water heater that heats the water up as you use it. Inline gas-fired heaters are more efficient, economical and produce less emissions than an equivalent electric system.
7.2.1 The business case A number of factors will go into determining the investment returns of a solar hot water system for your business:
Depending on climate and location in Australia, hot water from a solar hot water system may not be available all year round and you may need a backup system. Discuss your best option with your local solar hot water supplier.
• The cost currently paid for the fuel that drives your current hot water system e.g. electricty (including any peak network charges) • The temperature requirpments for hot water in your business and what a solar hot water system could produce, which is primarily driven by your location within Australia • The rate and volume of hot water you require.
7.3 Solar power Solar power is created by photovoltaic (PV) panels which are generally fitted on the roof in a northerly direction and at an angle to maximise the amount of sunlight that hits the panels. Solar PV panels generate electricity by converting the energy in sunlight using modules of specially fabricated materials that make up the solar panels. In most cases solar panels are connected to the mains power supply through an inverter. Businesses with solar systems use solar power first before sourcing electricity from the grid and with rising energy prices, an investment in solar power will only improve in value over time.
A number of factors will go into determining the investment returns of a solar system for your business: • The cost currently paid for electricity (including any peak network charges) • How much electricity the solar system would produce which is primarily driven by your location within Australia • How much of the solar electricity production could be utilised at the time of generation and how much would be sold back into the electricity grid. The more of the solar electricity that is used directly and not put back into the grid the better the business case – you pay more for electricity from the grid than the retailers will pay you for electricty you can supply to them.
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7.3.1 The business case
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There are now innovative pricing models on the market where the solar PV company will pay for the supply, install and maintenance of solar panels on your roof, in exchange for you agreeing to buy the electricity it produces, often at better than market rates for grid electricity.
7.4 Wind power Although not as common as solar energy, wind energy is starting to catch on with retailers around the world. Wind power is generated by a wind turbine which is connected to the grid or a battery system. There are several types of turbines however, for small systems, helical turbines are gaining popularity. Before you can install a wind turbine in an urban area you will need to understand what technology is available and whether there is sufficient wind speeds to make it viable. You will also need to address other issues such as grid connection and local planning requirements. Your wind power provider should provide you with this information in their proposal Sustainability Victoria has produced a guide1 for businesses considering installing a small wind turbine to generate electricity on their site. The guide is designed to assist you to make an informed decision about whether to purchase a wind turbine system and what type of wind system to get.
7.4.1 The business case A number of factors will go into determining the investment returns of a wind turbine for your business: • The cost currently paid for electricity (including any peak network charges) • How much electricity the wind turbine would produce which is primarily driven by your location within Australia i.e. how windy it is • How much of the wind electricity production could be utilised at the time of generation and how much would be sold back into the electricity grid. The more of the wind electricity that is used directly and not put back into the grid the better the business case – you pay more for electricity from the grid than the retailers will pay you for electricty you can supply to them • The cost of the wind turbine • The cost of connecting the system to the grid • The planning permissions required to proceed with the installation.
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Victorian Consumer Guide to Small Wind Turbine Generation, Sustainability Victoria, July 2010; www.sustainability.vic.gov.au/resources/documents/Small_Wind_Generation1.pdf.
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7.5 Other energy sources There are a number of other potential energy sources that exist however their suitability to supermarkets in Australia is limited at this point due to relatively low energy prices. These include: Hydro
Hydro electricity is electricity generated by water, or other liquid, flowing past and turning a turbine that is connected to a generator to produce electricity.
Geothermal
Geothermal electricity is electricity generated from geothermal energy. Generally water is heated up using the geothermal energy and turned into steam. The steam is then used to drive a turbine that is connected to a generator to produce electricity. Geothermal energy is also used to generate heating and cooling directly without the generation of electricity e.g. using a heat pump or an absorption chiller. Some areas of Australia have excellent access to geothermal energy and local expertise should be sought to explore the relevance of this energy source to your business.
Biomass
Biomass, or biological material (e.g. plant materials), can either be converted into an energy product such as biofuel. This fuel can then be used as a liquid fuel to power a generator to produce electricity on your site.
Biogas
Biogas is a combustible gas produced from waste through anaerobic digestion. The gas is used to fuel a gas combustion engine that produces electricity.
Cogeneration
Cogeneration is the generation of useful heat and electricity from one fuel source (also know as a ‘combined heat and power plant’). Cogeneration plants can run on any fuel however natural gas fuelled cogeneration plants are often the most economically viable.
Trigeneration
Trigeneration is an expansion of Cogeneration where the plant produces heat, electricity and cooling.
Case Studies Milner Meat and Seafood Alice Springs, Northern Territory A 10kW solar PV system was installed, producing over 16,000 kWh per annum, providing 8% of total the electricity consumption of the buiding. The system will result in a saving of almost $4,500 off the annual electricity bill.
Resources 1. Victorian Consumer Guide to Small Wind Turbine Generation, Sustainability Victoria, July 2010. www.sustainability.vic.gov.au/resources/documents/Small_Wind_Generation1.pdf.
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2. Consumer guide to buying household PV panels, p4; Clean Energy Council; December 2012. www.cleanenergycouncil.org.au/resourcecentre/Consumer-Info/solarPV-guide.html
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Glossary of terms – Alternative sources of energy Biofuel
A fuel derived directly from living matter.
Chiller
A generic name for a packaged refrigeration system that often includes a compressor, evaporator heat exchanger, condenser, water heat exchanger and control systems.
Compressors
Device that accepts gaseous refrigerant from the evaporator and compresses it to a higher pressure before it is sent to the condenser for heat rejection.
Environmental footprint
Demand for the earth’s natural capital as an impact based on the consumption of natural resources.
Heat recovery
An energy recovery heat exchanger that recovers heat from hot streams with potential high energy content, for example heat from refrigeration systems.
Heat exchanger
A device for transferring heat from one medium to another.
Heat pump
A device that transfers heat from a colder area to a hotter area by using mechanical energy.
HVAC
Heating, Ventilation and Air-conditioning.
Inline gas-fired water heater
Also known as tankless water heaters, they provide hot water only when required. They do not produce the standby energy losses associated with storage water heaters.
LPG
Liquefied Petroleum Gas. It is a flammable mixture of hydrocarbon gases (Propane or Butane) used as a fuel in heating appliances and vehicles.
Waste heat
Rejected or escaping heat from furnaces of various types after it has served its primary purpose.
Appendix – Average daily power production from solar PV systems Average daily production City
1 kW system
1.5 kW system
2.0 kW system
3.0 kW system
4.0 kW system
Adelaide
4.2 kWh
6.3 kWh
8.4 kWh
12.6 kWh
16.8 kWh
Alice Springs
5.0 kWh
7.5 kWh
10.0 kWh
15.0 kWh
20.0 kWh
Brisbane
4.2 kWh
6.3 kWh
8.4 kWh
12.6 kWh
16.8 kWh
Carins
4.2 kWh
6.3 kWh
8.4 kWh
12.6 kWh
16.8 kWh
Canberra
4.3 kWh
6.45 kWh
8.6 kWh
12.9 kWh
17.2 kWh
Darwin
4.4 kWh
6.6 kWh
8.8 kWh
13.2 kWh
17.6 kWh
Hobart
3.5 kWh
5.25 kWh
7.0 kWh
10.5 kWh
14.0 kWh
Melbourne
3.6 kWh
5.4 kWh
7.2 kWh
10.8 kWh
14.4 kWh
Perth
4.4 kWh
6.6 kWh
8.8 kWh
13.2 kWh
17.6 kWh
Sydney
3.9 kWh
5.85 kWh
7.8 kWh
11.7 kWh
15.6 kWh
The rated output is that achieved in perfect laboratory conditions. The CEC design summary software takes these deratings into account when predicting average for any given system. Source: Consumer guide to buying household PV panels, p4; Clean Energy Council; December 2012. http://www.cleanenergycouncil.org.au/resourcecentre/Consumer-Info/solarPV-guide.html
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