There are several benefits for manufacturers to invest in energy-efficient processes and technologies:
- Reduced costs.
- Improved productivity.
- Increased predictable earnings.
- Reduced carbon emissions.
- Meeting corporate environment goals.
Manufacturers can also improve competitive advantage through designing and manufacturing energy-efficient products. This achieves greater product differentiation, market share and customer loyalty.
Significant energy savings can be gained through optimisation of existing equipment and upgrading where possible. Improving real-time process data-monitoring and benchmarking will support this process.
Some examples of energy-efficiency opportunities are outlined below.
Operating temperatures and pressures
Manufacturing equipment operates at varying temperatures and pressures. Ensuring all equipment is operating at optimal settings saves energy.
Assess pressure requirements of the plant. Identify where you can reduce energy use without affecting core processes.
Operate air compressors at the lowest required pressure settings to reduce energy use for that equipment by up to 10%.
Review air-conditioner or cool-room settings and widen the temperature band where feasible to reduce:
- energy consumption
- loads on refrigeration plant
- the possibility of equipment failure.
Other opportunities include:
- operating extraction fans only when equipment is in use
- providing make-up air close to the equipment
- ensuring the make-up air inlet is closed when equipment is not in use.
Many manufacturing plants have equipment running when it’s not in operation.
Install timers to turn machinery and equipment off or to idle setting. This can be done easily for appliances such as air compressors and air conditioners, as well as lighting.
Be sure to fix or replace temperamental equipment so that everything can be turned off and on regularly without the risk of not restarting.
Identify and insulate equipment that continually loses or gains heat when not delivering useful services.
There are many ways to improve the efficiency of lighting equipment in manufacturing plants, such as:
- manual or automated control of lights
- increased levels of natural daylight
- installation of LEDs or induction alternatives to ageing fluorescent and high-bay lights.
See the Lighting guide for more information.
Individual HVAC unit components, such as motors, can be replaced with high-efficiency versions. There are also ways to generate energy savings from existing HVAC systems, including:
- passive solar design techniques to heat and cool air-conditioned spaces
- improved building insulation
- high-performance glazing, external window shading and proper window coverings
- reflective cool roofs
- minimising air leakage through the building envelope
- operating the system only when and where needed, using timers and individual zone control.
See the HVAC guide for more information.
A motor system includes the motor itself, the components it drives (pumps, fans and air compressors) and its controls. Best practice motor management considers how these work together and can deliver significant energy savings.
Approximately 5% of a motor’s lifetime cost is for purchase, installation and maintenance. The remaining 95% is for the energy used, meaning the purchase cost of a premium energy-efficient model will be paid back many times over on energy savings alone.
Premium motors also have indirect cost-savings through longer bearing life, insulation life and less vibration. They also run cooler, reducing the plant cooling load.
The use of variable speed drives combined with high-efficiency motors and improved motor system management can also unlock energy savings.
See the Energy Rating website for a searchable database of electric motors with information on energy efficiency.
See the Motors and variable speed drives guide for more information.
When compressed air load has been reduced and leaks in the distribution network have been repaired, a correctly sized compressor can be installed to increase energy efficiency.
Air compressors are most efficient when near full load. As a result, the best air compressors are sized correctly for the application. If the load is unavoidably variable, a combination of smaller compressors and variable speed drives may meet the load more efficiently. One compressor can meet the baseload, with the others coming online to meet peak loads.
Types of compressors include:
- rotary tooth.
While each type has its advantages and disadvantages, reciprocating and centrifugal compressors are generally the most efficient.
Peak loads can also be reduced by using storage receivers, which can store 5% to 10% of compressor capacity.
See the Compressed air guide for more information.
Modern boilers are a good investment as they don’t waste energy by unnecessarily turning on to recover standing losses during non-operation. They avoid this form of energy waste with:
- timing controls
- performance monitoring systems
Further efficiencies can be achieved by investing in solar water heating systems. To save energy, these systems preheat boiler feed water up to 80ºC. This suits a wide range of food and beverage processing plants.
See the Process heat and steam guide for more information.
Heat loss minimisation
Investing in insulation for roofs, walls, boilers and pipe-work can minimise heat loss and yield energy savings. It also has significant co-benefits through reducing heating and cooling loads.
Try to limit losses from boiler systems by insulating valves, steam and condensate return pipes, and storage units.
There are heat recovery opportunities in many manufacturing sectors. Those sectors with high-temperature processes or steam generation and boilers are especially suited to heat recovery.
Co-generation systems use heat, steam or waste gases to produce both electrical and thermal energy. Tri-generation (producing cooling as well as electricity and heat) can suit some sites.
Co and tri-generation systems are ideally suited to manufacturing plants. That’s because they produce the most energy when plants are running at close to 100% capacity.
Most systems are found in energy-intensive manufacturing sectors, which include:
- chemicals and plastics
- pulp and paper
- food and beverage
- petroleum refining.
Developments in small-scale co-generation, such as micro-turbines and fuel cells, are also opening up opportunities.
See the Waste heat recovery guide for more information.
Process integration saves energy costs in manufacturing plants with multiple heating and cooling demands. Linking hot and cold processes can reduce heat losses and identify heat recovery opportunities.
Pinch analysis helps to do this. It can identify and correct the ‘pinch’ (performance limiting constraint) in a manufacturing plant by using two composite curves—one for heating and one for cooling.
Plotting the two curves on a temperature-enthalpy graph reveals the pinch and corresponding energy targets (minimum feasible energy use for heating and cooling). Heat exchanger networks can then be designed to link processes to meet these targets.
Pinch analyses can be conducted on both new and existing plants.
Take a collaborative approach to energy and carbon management within the supply chain. Helping participants to better coordinate can improve the whole production process and bring large savings.
Supply chain management also addresses customer expectations around sustainability and helps maintain a competitive edge.
Strategies may include engagement with suppliers to encourage energy-efficiency investment and changing purchasing policies to favour lower embodied-energy materials.
High-temperature insulation is increasingly being used in manufacturing applications, including for processes that reach in excess of 1000°C. Materials used in these applications include alumino-silica and mullite ceramic fibres, calcium silicate, and mineral wool fibres. Such materials are available in numerous grades, compositions and consistencies, all of which can affect maximum insulating capacity.
Innovations in heat exchangers have enabled heat recovery from processes that were previously too extreme due to high temperatures, high pressure or hazardous chemicals. This has been made possible through the use of new materials that are resistant to corrosion or can tolerate higher temperatures and pressures.
Advanced ways to generate high-temperature fluids and steam are also showing promise, such as the use of solar thermal and heat-pump technologies. Other process innovations include the use of microwave kilns and dryers, and component manufacture using 3D printing.
Improved processes in composite fibres and light metals are making it possible for transport vehicles to be significantly lighter, saving more energy.
Business Energy Advice Program
The Australian Government's Business Energy Advice Program (BEAP) offers a free energy advisory service with one-on-one consultations. BEAP can help manufacturers understand their energy savings opportunities, choose the best energy plan, with tailored advice on energy efficiency opportunities best suited to their industry.
Small businesses with between 6 and 20 employees qualify for a free consultation, and businesses with 5 staff or less that have been adversely affected by drought are also eligible. Register by calling 1300 415 224 or visiting businessenergyadvice.com.au.
Small Business Energy Check
BEAP also offers an energy spend benchmarking tool for small businesses to compare their energy spend against similar businesses in their region. It can be used on its own, or in conjunction with a Business Energy Advice consultation. The Small Business Energy Check tool is available at checkyourenergyspend.com.au. You can use it as many times as you like, no registration is required.
Case studies Clean Energy Finance Corporation
Case studies Sustainability Victoria