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Concepts Of Energy Management

S. Binod, M. IEEE


Course Outline

This one hour online course provides a basic understanding of the various aspects of energy management.

This course includes a multiple choice quiz at the end.

Learning Objective

At the conclusion of this course, the student will:

Course Introduction

The course intends to create awareness of various aspects of energy management to the users. The course discusses various techniques of energy management applicable to buildings as well as industrial applications.

Course Content

Definition:

The Major costs involved for the building includes Construction / Financing costs, Energy Costs, Operating Costs and Retrofit Costs. And the average life expectancy of a modern building is 40-50 years.

Of the above, the energy costs are found to be significant, and this varies according to the Total Area of the building, Type of building, Type of Electrical loads and etc. The energy costs, operating costs are recurring costs, which are found to increase with time.

The Electrical loads of various utilities, for a modern multistoried building as expressed on percentage basis gives the following data:

i) HVAC : 60 %
ii) Lighting : 23 %
iii) Lifts: 6 %
iv) Others: 11 %

The energy costs shall depend on this and period of use of these utilities. The energy and operating costs of the buildings can be reduced by methods involving energy conservation. From mechanical engineering aspect, improved thermal insulation, alignment of building, use of double glazed windows, air-conditioning controls etc. provide scope for energy conservation.

From electrical aspect, electronic building controls and energy efficient lighting system design & operation, energy efficient pumping systems provide scope for energy conservation.

The scope for energy conservation exists for all aspects of building services including Heating, Ventilation & Air-conditioning, Electrical systems, lighting systems, Water supply and Sewerage systems, Centralized Gas Supply, Heating etc.

Energy Management System for buildings:

Energy management system suited for operating for a building can be termed as building management system. This system can be used to monitor and control all or some aspects of building services including heating, ventilation and air-conditioning (HVAC), electrical systems, lighting systems, fire alarm and detection system, security systems including CCTV, public addressing, sensors, access control etc.

Heating, Ventilation & Air-conditioning Systems:

The simplest form of energy management system for HVAC system is the thermostat, which minimizes energy consumption on a time temperature basis. Another simple energy management system is achieved with load-cycling controllers, which make use of (on-off operations) to reduce consumption.

A higher level of control is achieved with demand controller (which effectively monitors the electrical demand and on a predictive basis disconnects and reconnects major loads. The most sophisticated control, which is practical even in moderate-size building with the HVAC energy management system, usually incorporated into the building control system.

Lighting:

The objective of Energy Management in lighting is to use more efficient lighting equipment and practices to achieve same or better lighting result for lower electrical energy consumption and lower cost.

The important aspects of providing better energy efficient and effective lighting are:

i) Selection of light source:

Compact fluorescent lamps are found to be more energy efficient and effective, when compared to GLS lamps. The CFL lamps available at 7/9/11 W are comparable to GLS lamps of 40, 60 & 100 W. Use of CFL lamp instead of GLS lamp will thus produce an energy saving up to 60%.

Similarly, switching to lower rated HPSV lamps instead of HPMV lamps can bring down energy costs substantially for large areas and major roads.

ii) Selection of light fixture and accessories:

Selection of light fixture plays an important role in proper distribution of light output and the lighting effect created. A well-designed optical system based light fixtures generates the optimum light output with maximum visual comfort.

For office areas, antiglare mirror optic light fixture suited for use with twin fluorescent lamps is advisable as it generates the light output, suited for continuous working hours.

Use of High Frequency Electronic Ballasts can improve performance of the lamps and has a high power factor with minimum interference for communication / data signals.

Electrical Power Systems:

Design stage itself care shall be taken, in selection of cables, all equipment and accessories. A considerable quantity of energy is wasted in distribution of Power, mainly by use of lower rated cables, faulty connections & terminations. This aspect is to be studied and rectified at the design /construction stage itself. Proper maintenance of all HV/LV equipment including HV panel, transformer, DG sets are absolutely necessary for preventing wastage of energy.

For all multistoried buildings, it should be a practice to maintain records of periodic maintenance and defects rectification.

Water Supply and Sewerage Systems:

Conservation of energy for the above systems mainly lies in selection of motors and pumps, fire fighting pumps etc. Regular maintenance of supply lines, overhauling of equipment are necessary for preventing wastage of energy.

Elevators:

Apart from interfacing with Building Automation system, elevators have independent microprocessor based control for efficient operation. Variable voltage, variable frequency drives, lift bank control (Duplex / triplex) & Automatic Rescue Device are advancements in elevators that help in optimum usage of elevators and safety of passengers. Variable frequency variable frequency drives used for elevators are considered the most energy efficient.

The controls from the elevator panel can be interfaced with the building automation system for monitoring and control as per Client's needs.

Methods for Effective Energy Management:

1. Efficient utilization of available energy resources.

2. Conservation of energy.

3. Technology development for recovery of waste energy.

4. Use of renewable energy systems.

5. Energy Auditing & prevention of leakage of energy.

 

( Ref:- Theme paper on Energy Scenario)

The energy consumption for various utilities and services expressed in percentage is as shown in the pie diagram. From the diagram it can be seen that, Industry account for 43 % of the total energy consumption.

Energy costs is generally major factor in the manufacturing industry. Energy management in the industry can be achieved by use of energy efficient equipments, audit of energy flow in the system, creating awareness among end users. By detailed energy audit, it is possible to reduce energy cost by 10- 20 %. Even in the best managed industrial concerns, 6-8 % energy saving is possible without major investment.

The required capacity as estimated above can be reduced by 20-25 % by adopting energy conservation measures and through demand side management. This can reduce the capital investment required by 25 %. A unit of energy saved is equivalent to a unit of energy generated becomes relevant in this context.

Energy Management - Power supply Sector:

The Energy management aspects to be adopted by power supply companies should cover all possibilities in generation, transmission and distribution. The major fronts in which energy management can be achieved includes:

Power factor reduction from 0.8 to 0.6 derates the system installed capacity by 25 %. This shall include capacities of generator, transmission line, distribution transformer and subsequent low / medium voltage feeders.

Low power factor results in drawing higher currents, thus further escalating energy costs. Low power factor causes excessive voltage drops in the system, thus affecting the life of all low voltage equipments.

Power capacitors shall be used, which enables reduction of KVA demand for given KW load thus reducing energy costs. Higher power factor shall improve performance, capacity and expected life of all system equipments including transformer, generator, switchgear and cables.

Power management systems are primarily used for control and monitoring of electrical distribution system for effective and efficient management.

A typical PLC based power management system shall include Programmable Logic Controller, connected to I/O racks, interfacing systems with power monitors & various third party devices. The PLC can interface with plant process control systems to gather data and control signals through data networks. The PLC can be integrated with overall plant control scheme.

The PLC hardware system along with the software are equipped to perform reading of all power data and giving information in standardized data tables and giving alarm signals. The system provides display, logging and analysis of collected power data. The system can allocate power costs to various departments and utilities. Other system functions shall include providing demand management and load shedding.

Energy Audit:

Each industry / major company should have an energy cell for control & management of energy. The cell shall study the existing system parameters and should identify areas, where energy can be saved. The cell shall line up implementations for energy conservation and create awareness among end users.

Methodology shall be to document various proposals for energy saving compiled along with technical details for their implementation, expected annual saving against estimated costs of implementation, simple pay back period etc.

An energy audit shall involve collection of detailed information on the process, equipment used, illumination systems, heating, ventilation and air-conditioning systems, boilers, pumps etc. Based on the information, the energy costs of specific areas/processes can be worked out, which enables formulation of an energy consumption chart. The energy consumption chart can be verified for finding surplus use of energy compared to similar systems, leakage of energy in the system, and help us in suggesting energy efficient schemes/equipments for specific areas.

Each of the energy saving measures and systems are further studied in detail for savings in energy return of investment, system performance, integration with existing system etc.

The energy saving measures to be followed by an industry shall include periodic measurement of all energy resources i.e. electrical energy, coal, gas, boiler, mechanical systems etc.

The energy costs shall be done area wise and should be related to production costs. Energy indices are to be prepared for analysis of data. Energy indices can be developed for various industries - textile, cement, chemical, hotel, transportation etc. The indices can be expressed as unit of energy consumed for a specific output of end product. This specific energy costs are found to remain within a certain range for industries working under similar conditions.

In the prevailing situation of severe competition in the market, cost reduction has become very important for improving profit margin as well as for survival and specific energy consumption has to be made optimum to achieve better performance.

The requirement to achieve energy efficiency is increasing, as now the energy agenda has shifted from strictly economic concerns to more global environmental ones. A ban is imposed on the use of chlorofluorocarbons which depletes the ozone layer is going to be enforced by 2010. Now environmental parameters do also necessitates conservation of energy and utilization of renewable energy systems.

Methods for Energy Conservation:

Energy efficient lighting systems

Energy saving systems - Measurement methods

Building automation systems

Renewable energy systems

Solar Photovoltaic systems are the most important among the renewable energy system finding its application in household and industrial systems. Solar photovoltaic primarily uses sun's light energy and converts it into electricity through solar cells.

The solar systems can be as simple as an individual system as solar water heater where solar energy directly powers the functioning of the system. The system can function only when sunshine is available.

A more complex system is the home lighting system, which includes a battery backup for operating at night, and powering both AC and DC loads.

The above systems works independently, but solar system can also be used in conjunction with other complementary power sources to provide complete energy solutions.

The solar energy's unique attributes of needing no fuel, high durability and reliability and being able to operate for prolonged periods without maintenance make it economical for all types of remote applications. These unique attributes permit solar energy to be used in places and for purposes where no other power source is feasible.

A typical solar photovoltaic system shall include sunlight as the fuel, solar modules, charge regulators, batteries, inverters, mounting structure, internal wiring, back up generators etc.

Solar modules generate DC electricity directly form sunlight, charge regulators link the modules, battery and load. Also, charge regulators protect battery from overcharge or excessive discharge. Batteries store the energy generated by solar modules and inverter converts DC electricity into AC for powering equipments.

The mounting structures are used to hold the solar modules securely in place either at ground /roof or at poles. Back up generators are required for excessive power demands or during unanticipated sunless periods.

Solar systems are considered as one of the easiest and most reliable way to generate electricity. Regular maintenance to check wiring, connections, batteries and overall system condition will help assure long-term trouble free operation.

Grid connected solar power systems powering loads up to 2 MW are being used at present for peak handling of loads, powering day loads of agricultural pumping in remote areas and for telecommunication applications.

Non-Conventional source of energy for Buildings:

Among the various sources of non-conventional energy, solar energy is most suited to be utilized as an alternate power source for buildings.

Solar photovoltaic power systems basically include solar module, battery system and electronic circuitry. The main application for this system is in lighting, water pumps, remote telephone exchanges etc.

Based on application, solar photovoltaic system can be stand-alone type PV power system or grid connected PV power system.

In buildings, standalone type shall include independent solar modules, batteries, electronic circuitry and the lighting loads connected to it. Standalone systems are applicable for outdoors lighting, streetlights and for remote telephone exchanges.

A larger type stand-alone system is suited for community housing, large buildings, where a central system shall feed power to all loads. The central system shall include bank of solar modules, battery system, electronic circuitry etc. This system is adapted for buildings, where a part of the lighting load is taken care of by the solar photovoltaic system.

Higher initial investment and occasional low performance of electronic circuitry in the SPV system may be deterrents in opting for a total SPV system.

Solar photovoltaic system is suited for low power applications, where mostly lighting loads are to be connected. It would be most appropriate to opt for a combination of normal power and SPV power, as it would prove to be economical and reliable system.

The hybrid systems are found to be most suited for applications involving continuous operation and reliable system. In remote telephone exchanges and army posts hybrid of solar photovoltaic system with diesel generating sets are widely used and appreciated for the reliability of operation.

Course Summary

Energy Management system is becoming a widely accepted concept, with rise in energy costs, non-availability of quality power and increased awareness about energy management among consumers.

Creating awareness regarding need for energy management, incentives for best energy managed companies and Power tariff structure suited to encourage energy saving can improve the existing power situation and will help in formulating a better planned power supply system.

An integral energy management system for a building for controlling and monitoring of data, requires considerable investment. And neither monitoring nor controlling, is an end in itself, there have to be reasons and ultimate objectives in investing considerable amount of sum, in this regard.

The investment varies depending on the type of building, Range of parameters to be monitored, utilities to be connected to the system and level of sophistication.

Hence in opting for an energy management system, care shall be taken to arrive at an appropriate system, with desired level and range of operation. The monitored parameters are to be recorded and studied carefully, to evolve necessary steps and maintenance schedules for optimum use of energy.

Related Links

For additional technical information related to this subject, please visit the following websites or web pages:

Federal Energy Management Program
Energy Management Systems

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