There are numerous energy efficiency opportunities in the manufacturing sector.
Optimise the use of existing equipment
Improving real-time process data monitoring and benchmarking can support optimisation of existing equipment. Significant energy savings can be achieved through minimising heat gains and losses, enabling greater control of process temperatures and shutting down equipment when it is not required.
Some examples of opportunities in this area are outlined below.
Implement effective shut down procedures to minimise energy overheads
Most manufacturing plants have energy overheads, that is, energy-using equipment which is left on even if the plant is not producing any product. This can be addressed:
- with good control engineering, by installing timers to turn machinery and equipment off or to idle setting when not required (including equipment such as air compressors, air conditioners and lighting)
- by fixing or replacing temperamental equipment so that all equipment can be turned off and on regularly without the risk that it won’t restart
- identify and insulate equipment that continues to lose or gain heat when useful services are not being delivered.
Optimise operating temperatures and pressures in general manufacturing
Manufacturing plants have equipment operating at different temperatures and pressures. Ensuring all pieces of equipment are operating at optimal conditions saves energy. For example:
- operating air compressors at their lowest possible settings (e.g. 690 kPa/100 psi instead of 830 kPa/120 psi) could reduce energy requirements for that equipment by 10%
- reviewing air-conditioner or cool-room settings and widening the temperature band where feasible, can reduce energy consumption, reduce loads on refrigeration plant and lower the probability of equipment failure
- assessing pressure requirements could identify opportunities to reduce energy use without impacting on core manufacturing processes.
Other opportunities should also be explored such as operating extraction fans only when equipment is in use, providing make-up air close to the equipment, and ensuring that the make-up air inlet is closed when equipment is not in use.
Reduce demand in lighting and HVAC systems
There are many ways to improve the efficiency of lighting equipment in manufacturing plants, such as:
- manually or automatically turning off lights when and where not needed
- increasing levels of natural daylight within rooms (which can reduce electrical lighting loads by up to 70%).
See the Lighting page for more information.
There are also steps that can be taken to generate energy savings from existing HVAC systems, including:
- using passive solar design techniques to heat and cool air-conditioned spaces such as allowing direct sunlight to penetrate windows in winter and using natural ventilation in summer
- reducing heating and cooling demand through improved building insulation, high performance glazing, external window shading, proper window coverings, reflective cool roofs and minimising air leakage through the building envelope
- operating the system only when and where needed by using timers to control system operation and providing individual zone control to turn off heating or cooling where not required.
See the HVAC technology page for more information.
Optimise operation of motor systems
A motor system includes the motor, the components it drives (e.g. pumps, fans and air compressors) and its controls. Optimising the operation of a motor system when coupled with best practice motor management can generally deliver energy savings of between 30% and 60%. Optimisation considers the interaction of energy supply and energy demand.
Improve the efficiency of existing equipment in manufacturing
The efficiency of existing equipment can be improved through proactive maintenance, reducing heat loss and optimising the conditions under which the equipment operates. Implementing these opportunities can provide rapid return on investment.
Some examples of opportunities in this area are outlined below.
Minimise heat loss
Investing in insulation for roofs, walls, boilers and pipe work can minimise heat loss and yield energy savings for particular equipment. It also has significant co-benefits through reducing heating and cooling loads.
For example, heat from boiler systems can not only negatively impact on the energy required to maintain boiler temperatures but can also increase requirements for air-conditioning cooling loads. Minimising heat loss from boiler systems should be focused on insulating boiler valves, steam and condensate return pipes and storage units.
Implement preventive maintenance of current equipment
Implementing a preventive maintenance program can have significant cost and production benefits.
- For motors and pumps, maintenance prolongs equipment life and operating efficiency and identifies potential failures that would cause downtime. A maintenance program can save up to 30% of total motor system energy use and save 2–7% of pump system energy use.
- Lubricating air compressors and checking for leaks in the distribution network can avoid unnecessary and costly downtime due to equipment failure.
- Leak repair and maintenance can reduce the compressed air losses in equipment from 20–50% down to 10%. Leak repair alone can reduce energy consumption by 20%.
See the Compressed Air technology page.
Invest in equipment upgrade in manufacturing
Energy efficiency improvements can be achieved through upgrading, ensuring it is sized correctly, and by replacing inefficient older equipment. Some examples of opportunities in this area are outlined below.
Invest in more efficient HVAC systems
Premium (high-efficiency) HVAC units use up to 40% less energy than units that just meet minimum standards. Individual HVAC unit components such as motors, can also be replaced with premium efficiency models.
See the HVAC page.
Invest in more efficient motors
Of a motor’s total cost, up to 95% is for the energy used over its life time and only about 5% is for purchase, installation and maintenance. Premium motors also have longer bearing life, longer insulation life and less vibration. They also run cooler, reducing the plant cooling load.
Therefore, investment in a premium motor can pay back the purchase cost many times over with energy savings and indirect cost savings.
The use of variable speed drives (VSD) combined with high-efficiency motors and improved motor system management can also unlock energy savings.
Invest in more efficient boilers
Modern boilers use timing controls, performance monitoring systems and alarms to avoid dry cycling. ‘Dry cycling’ occurs when energy is wasted due to a non-operating boiler turning on unnecessarily to recover standing losses. Many older boilers are prone to dry cycling because they have fewer controls, so modern boilers are a better option.
Further energy savings can be achieved by investing in solar hot water heating systems. These systems save energy by preheating boiler feed water up to 80ºC, which is suitable for a wide range of food and beverage processing plants.
Invest in more efficient air compressors
After a compressed air load has been reduced and any leaks in the distribution network have been repaired, a new correctly sized compressor can be installed to increase energy efficiency.
Since air compressors are most efficient when near full load, the best air compressor system is one which is appropriately sized for the application. If the compressed air load is unavoidably variable, a combination of smaller compressors may meet the load more efficiently. One compressor can meet the base load, with the others coming online to meet peak loads.
There are many types of compressors, including reciprocating, vane, screw, centrifugal, scroll, and rotary tooth. Each type has its advantages and disadvantages, but generally, reciprocating and centrifugal compressors are the most efficient. Peak loads can also be reduced by using storage receivers, which can store 5–10% of compressor capacity.
See the Compressed Air technology page.
Undertake process integration
In manufacturing plants with multiple heating and cooling demands, process integration saves energy costs through linking hot and cold processes to reduce heat losses and identify heat recovery opportunities.
Conduct a pinch analysis
Pinch analysis aids process integration by identifying and correcting the ‘pinch’ (performance limiting constraint) in a manufacturing plant.
It uses two composite curves—one for heating and one for cooling. Plotting the two curves on a temperature-enthalpy graph reveals the pinch and the corresponding energy targets (minimum feasible energy use for heating and cooling). Heat exchanger networks can then designed to link processes to meet these targets.
Pinch analysis can be conducted on both new and existing plants.
Implement heat recovery
There are heat recovery opportunities in many manufacturing sectors, especially those with high temperature manufacturing processes (e.g. for metals, chemicals, cement, ammonia and lime manufacturing) and those using steam generation and the use of boilers (e.g. paper and pulp manufacturing).
Cogeneration systems use heat, steam or waste gases to produce both electrical and thermal energy. Trigeneration (producing cooling as well as electricity and heat) can be appropriate at many sites.
Cogeneration and trigeneration systems are ideally suited to manufacturing plants as they produce the most energy when the plants need it most, when they are running at close to 100% capacity. Most co- and tri-generation systems are found in energy intensive manufacturing sectors, including steel, aluminium, cement, paper and pulp, chemicals and plastics, food and beverage, and petroleum refining. Developments in small scale co-generation such as micro-turbines and fuel cells are also opening up opportunities.
- Cogeneration opportunities in the commercial buildings sector.
- Waste heat minimisation and recovery technology page.
Design products for high-efficiency performance
Manufacturers can improve competitive advantage and build greater customer loyalty through designing products that use significantly less energy.
Some recent energy-efficient product designs include:
- equipment and appliances with effective standby functions
- lighting solutions such as compact fluorescent lamps (CFLs) or light emitting diodes (LEDs) with better illumination and longer lifetimes
- fuel-efficient and lightweight vehicles, including motorcycles, trucks, trains and aircraft
- insulation materials, double or triple glazed windows and other efficient construction materials.
Collaborate with supply chains
A collaborative approach to carbon management within the supply chain has the potential to realise large savings. Strategies to improve energy efficiency need to include engagement with suppliers to encourage them to invest in energy efficiency opportunities and changing purchasing policies to lower embodied energy materials and energy inputs.
Innovations in a range of technologies are enabling greater levels of energy efficiency in the manufacturing sector. For example:
Innovations in materials science in Europe have led to a new insulation material that will allow refrigerators to be 50% more efficient. This new insulating material achieves R4 levels of insulation while still being very thin. This innovation will enable all heating and cooling appliances, including kettles, microwave ovens and refrigerators, to be significantly better insulated without adding bulk to the appliance.
Innovations in composite fibres and light metals are making it possible to design transport vehicles to be significantly lighter than previous models to enable further energy efficiency improvements.
Innovations in heat exchangers have enabled efficient recovery of heat from manufacturing processes that were previously too extreme due to high temperatures, high pressure or chemically hazardous environments. This has been made possible through using new materials that are resistant to corrosion or able to tolerate higher temperatures and pressures.