Compressed air system best practice programmes: What needs to change to secure long-term energy savings for New Zealand?

Abstract

The establishment of a compressed air system (CAS) best practice programme is a key component of one of the initial industrial energy efficiency programmes being driven by New Zealand government ministries and agencies. In a global context this is not a new initiative in that existing programmes have been functioning in Europe and USA, yet in each of these cases the impact ten years-on has been patchy with limited long-term improvements in overall energy efficiency. The New Zealand CAS best practice programme currently under development is sponsored by the Electricity Commission (EC) and the Energy Efficiency Conservation Authority (EECA). It takes a new approach in policy direction, with variations from those used in other international programmes. A significant level of electricity levy money is to be committed to this programme and it is timely to highlight its merits and potential weaknesses, and what is required to generate long-term energy savings beyond the levels achieved by more mature overseas programmes.

Introduction

Compressed air is a commonly used utility across most manufacturing and processing industries, with little attention typically given to the energy costs incurred. The energy savings gained through optimisation of a compressed air system (CAS) can be significant in dollar terms, yet several orders of magnitude lower than the potential costs incurred through system failure. Consequently most industrial compressed air systems are poorly designed, with an emphasis on risk aversion rather than actual operational efficiency. In most cases this results in systems being oversized, with spare installed capacity to insure against such losses, which typically compromises the long-term energy efficiency of the installation. As such compressed air systems have been an obvious and easy target of government and utility company energy efficiency programmes around the world during times of restricted supply or increasing energy costs. Interestingly the focus in such programmes have also declined with energy costs—suggesting that significant barriers exist to the independent adaptation of best practice energy efficient standards, often in the capital and time constrained workplace of a production plant.

The increasing political focus on climate change and greenhouse gas emissions coupled with energy infrastructure constraints have led to renewed focus on industrial energy efficiency, including the energy efficiency of CAS. Indeed CAS were identified as a significant opportunity in the Ministry of Economic Development (MED) New Zealand Energy Strategy of 2007 (MED, 2007) and in a previous policy framework, with associated work fostered by both the Energy Efficiency Conservation Authority (EECA) and the Electricity Commission (EC). Over 30% of the total annual energy use (excluding transport) in New Zealand (MED, 2006) is consumed by industry, with a large portion of this attributed to a relatively small number of users and industries. Compressed air was identified as one common utility that represented significant savings potential across a wide cross-section of these industries, with relatively low implementation costs. To this end the CAS best practice programme was established as one of the two initial industrial energy efficiency programmes sponsored by the newly created NZ Electricity Commission. Early work conducted by the Energy Research Group at the University of Waikato demonstrated this with savings of 20–30% identified in food, plastics and wood processing industries (Neale et al., 2006).

When compared with overseas best practice models for improving the efficiency of CAS the New Zealand programme is considerably less mature and in many ways has been modelled on a composite of these overseas examples. Given that the New Zealand CAS programme is being established with the use of electricity industry levy funds and is being managed through the EC (a public entity) it is timely to review the respective merits of these overseas models and how appropriately they can be applied in a New Zealand specific context. The discussion will also include specific performance metrics and a break down of the various aspects of the proposed programme covering CAS audits, training and auditor accreditation and the proposed funding model. The paper will discuss the CAS-related research and development work conducted by the authors and concludes with what needs to change to secure long-term energy savings on a sustainable basis, from a New Zealand perspective.