ENERGY AUDIT
By K K Dhingra, Executive Director, Petroleum Conservation Research Association

Energy audit helps in energy cost optimisation, pollution control, and safety aspects and suggest methods to improve the operating and maintenance practices of the system. It is instrumental in coping with the situation of variation in energy cost availability, reliability of energy supply, decision on appropriate energy mix, decision on using improved energy conservation equipment’s, instrumentation’s and technology.

The objectives
The energy audit provides the vital information base for overall energy conservation programme covering essentially energy utilisation analysis and evaluation of energy conservation measures. It aims at:

• Identifying the quality and cost of various energy inputs
• Assessing present pattern of energy consumption in different cost centres of operations
• Relating energy inputs and production outputs
• Identifying potential areas of thermal and electrical energy economy
• Highlighting wastage’s in major areas
• Fixing of energy saving potential targets for individual cost centres
• Implementation of measures for energy conservation and realisation of savings

 

Need for energy audit
Energy audit is a vital link in the entire management chain. The energy manager while proposing various courses of action and evaluating their consequences requires a detail information base to work from energy audit attempts to balance the total energy inputs with its use and serves to identify all the energy usage’s according to its discrete function.

Energy audit is an effective tool in defining and pursuing comprehensive energy management programmes. It has positive approach aiming at continuous improvement in energy utilisation in contrast to the financial audit, which stresses to maintain regularly. Energy audit provides the answer to the queries What, Where, When, Why and How.

Approach
The overall objectives of the energy audit are accomplished by:

• Identifying the areas of improvement and formulation of energy conservation measures requiring no investment or marginal investment through system improvement and optimisation of operations
• Identifying areas requiring major investment by incorporation of modern energy efficient equipment and upgradation of existing equipment
• Establishment techno-economic feasibility for proposed measures and suggestion for their implementation.

The entire process is broadly divided into two parts. The preliminary energy audit and the detailed energy audit. The Preliminary energy audit focuses on the major energy supplies and demands usually accounting for approximately 70% of total energy. It is preliminary data gathering and analysis effort. It uses only available data and is completed with limited diagnostic instruments. The detailed audit goes beyond quantitative estimates of costs and savings. It includes engineering recommendations and well defined projects, giving due priorities. Approximately 95% of all energy is accounted for during the detailed energy audit.

Evaluation of energy management projects and payback period
Energy management can be construed as the process of guiding and controlling energy user so as to yield the maximum possible output per unit of energy. It involves assessing the output to energy ratio for alternatives and choosing that alternatives which yields the most favourable output to energy ratio. To simplify the assessment and comparison of alternative technologies and processes, it becomes necessary to convert both output and energy units into money values.

Recommendation
Appreciable energy can be saved in production and distribution process by making relatively minor changes and modifications in technological and process components. The need for such a change can be identified through energy audit and value analysis perspective, whereby elements of technological or process over design or such optimal leads to suggestions to reduce energy wastage or improve energy recovery by replacing energy inefficient or broad tuning, energy controls, modifying insulation, installing relatively inexpensive equipment for leak plugging and introducing minor process changes to recover and recycle waste energy more effectively.

Technological and process alternatives which can be introduced over the short run for improved energy conservation and which entail relatively low expenditure over a few weeks or months, can be evaluated for their relative attractiveness by estimating their payback periods (PBP). The PBP gives an immediate indication not only of the time required to receive the cost of investment, component replacement or process changes but also the relative uncertainties to be faced in the alternative situations. The Break Even Point (BEP) gives an indication of:

* the minimum level of operation or output or throughput or capacity utilisation at which the total cost (investment plus operating and maintenance) of an alternative just equal to the total benefits or gross return.
* the floor or ceiling levels of technical efficiency or of input and output prices at which the total given level of operation or throughput.
* relative uncertainties associated with a lower BEP promising high probable financial performance under uncertain conditions.

Conclusion
PCRA’s experience in conducting energy audit and fuel optimisation studies indicate that about 10 to 15% fuel saving is just possible by maintaining simple good housekeeping habits like optimisation of combustion efficiencies of boilers/thermopac and furnaces, regular monitoring of traps/insulation quality etc. Majority of these savings can be attributed towards `Good Management practices’. By installing energy efficient system itself does not suffice the need but managing at its optimum condition is more essential. It needs in house development of conservation practices like regulation/monitoring/maintaining proper data. Analysis and quick energy conservation measures by each industry should be encouraged.