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Engineering and Fabrication business

  • Location

    Central Queensland
  • Size

  • Sector

  • Focus area

    • Compressed air
    • Solar

55% Proposed
energy savings

An energy assessment for a Central Queensland engineering, machining and fabrication company identified options to optimise energy consumption and costs, and to reduce the site’s greenhouse gas (GHG) emissions. Four efficiency improvement and energy reduction options have been identified, each with a payback period of two years or less. These offer a potential combined energy saving of 318 gigajoules (GJ) per annum and GHG savings of 72 tonnes of carbon dioxide equivalent (t CO2-e).

Two solar PV options have also been considered. A 200 kilowatt (kW) system is recommended, which would reduce annual GHG emissions by a further 202 t CO2-e.

Summary of Opportunities

Key Recommendations Capital Cost Annual Energy Savings (GJ p.a.) Annual Energy Cost Savings ($) Payback Period (Yrs) GHG Savings (Tonnes of CO2-e)
Compressed air VOCs/VSDs $20,949 253.6 $7,138 2.0 57.1
Compressed air line optimisation $3,000 11.1 $314 1.8 2.5
Tariff review $0 0.0 $5,911 Instant 0.0
Standby load review $1,500 53.1 $1,347 1.1 12
Battery for demand reduction $90,000 0.0 $13,278 6.8 0.0
200 kW solar $317,200 900 $25,332 12.2 202

Variable Output Air Compressor

The site’s existing air compressor has a remaining three to four years of operating life. There’s an opportunity to maximise efficiency and reduce operating costs by replacing it with a new $20,000 compressed air system with variable output control (VOC) and variable speed drives (VSDs).  Benefits of a new system include:

  • Ability to vary the speed of the compressor in response to variable compressed air requirements, thereby reducing consumption during the loaded state.
  • Overall lower electrical power required for the same air output due to improvements in air compressor technology since 2011.
  • Lower maintenance costs and lower operating temperature.

This solution offers a quick two-year payback period with substantial annual energy savings of 253.6 GJ and emissions savings of more than 57 t CO2-e.

Compressed Air Line Optimisation

Bends in the compressed air delivery line will cause preventable pressure loss in the system. A site visit uncovered numerous right-angled turns that could be easily eliminated without affecting the operation of the site. This option has a low capex at only $3,000 and would deliver annual cost savings of $1,630 and energy savings of 4.5 kW per annum.

Tariff Review

A tariff review presents a no capex option with a high cost saving potential. Regular tariff reviews will ensure the manufacturer is on the best tariff for the business’ current operating conditions. At the time of the assessment, it was found that by simply changing tariffs, the manufacturer could save $5,911 in annual energy costs.

Standby Load Review

The site has a significant baseload of about 20 kW which could contribute to as much as 24% of the annual energy consumption. It was found that it’s not unusual for some smaller equipment and lighting to be left on after a shift. Eliminating these standby loads could greatly reduce the site’s energy consumption. By identifying and eliminating the standby loads, the site could save 14,756 GJ of energy each year, resulting in annual cost savings of $1,063 and an emissions reduction of 11.95 t CO2-e per annum.

To be added as a feature/call-out box


Cutting Energy Use and Emissions with a Solar PV System

The financial cases of two solar PV solutions were modelled for the engineering and manufacturing business:

  • A large 200 kW system – this is intended to meet the maximum site load while also returning a positive net present value. This system can take advantage of large-scale generation certificates (LGCs).
  • A smaller 99 kW system – this is aimed at quickly installing a reasonably sized solar system for a lower capital investment. This system can take advantage of small-scale technology certificates (STCSs) to significantly improve the simple payback period.

To obtain the fastest payback period, a 99 kW system is the best option as the $102,651 capital investment will be paid off in seven years.

However, the 200 kW is recommended, given the assessment’s objective is to assist with long-term energy use and emissions reduction. The 200 kW system would reduce greenhouse gas emission by 202.5 t CO2-e per year (compared to the 99 kW system at 117.8 tonnes), and achieve energy savings of 249,989 kWh per annum (compared to 145,383 kWh for the alternative system).

Battery for Demand Reduction

With energy storage, manufacturers can more effectively participate in demand management opportunities, be more energy independent and resilient to grid instability, save on energy costs, and more.

Based on the site’s current energy consumption, a 50 kW/ 100 kW per hour (kWh) battery would provide savings of about $13,000 per annum. This solution would cost over $90,000 at the current market price for batteries making it non-viable. This option is recommended for consideration when the price of batteries has fallen further in coming years.