Using Energy Efficiently
Energy Control System
The efficient use of available energy is becoming more and more important for industrial firms in Germany. The basic sources of energy including electricity, gas, water and steam are available in almost all industrial operations. More than 15 different types of energy are used in some cases for complex production processes in, amongst others, the chemicals industry.
The Status Quo
For all intense purposes, zero potential savings remain for many companies from today's point of view. They have already drastically reduced material and personnel costs in the wake of the Lopez era by means of rationalization and a lean personnel policies. The energy costs incurred for the manufacture of a given product had previously been perceived as having subordinate importance. It is precisely this aspect which demonstrates new potential savings in the face of ever increasing energy costs.
Well founded knowledge regarding energy consumption and load profiles for the entire plant are, generally speaking, available. They are the basis for the contractual relationship with the power utilities, and are acquired at the point of transfer. Beyond this, allocation of energy costs within the plant, usually broken down on a building to building basis, is commonplace as well for historical reasons.
At the end of each billing period, the individual meter readings are recorded at considerable expense, and are then entered to the computer system. After performing plausibility checks and correcting errors, consumption is allocated on a percentage basis to the various cost centers. This flat-rate allocation of energy consumption leads to reduced energy efficiency because it does not reveal intensive production processes and bad energy consumption habits.
Potential savings for the individual cost centers cannot be exploited due to a lack of transparency. Energy consumed during high-load, as well as low-load hours is used for the calculation of the kilowatt-hour rate. An additional differentiation as regards usage quantities may take place within the time periods defined by the tariff. The demand rate is calculated based upon the maximum mean power value during the billing period at quarter hour intervals. This value is determined by the power utility, is recorded, and is used to calculate how much connected load will be made available.
Well founded approaches to the efficient use of all energy media only become apparent if precise knowledge is available concerning energy consumption patterns for a given user relative to time. Existing relationships between energy consumption and related events can be determined very quickly with this information. Investment decisions involving new systems with minimal energy consumption can be rapidly evaluated with this knowledge as well.
Peak Load Optimization
Above all, substantial potential savings result from the reduction or suppression of peak loads. Simple maximum value watchdogs and shutdown functions are integrated into the decentralized summators included with intelligent energy logging systems, which can be programmed by the customer with a simple programming language.
Complex optimization tasks are generally accomplished with a special optimization computer which uses the existing logging system as a data source, and shuts down consumers based upon complex trend calculations and priorities.
The best approach to this problem involves a mutual effort in cooperation with a partner who possesses the experience and consultation expertise required for the implementation of a system of this type. The partner provides the customer with suitable hardware, as well as proprietary standard software, which are both adapted to the needs of the user. Under the most favorable conditions, previously installed systems from other manufacturers can be integrated. In-house expenses must also be taken into consideration, which are incurred as a result of cooperation provided by the individual departments who are responsible for the various energy media. Cooperation of this sort is necessary right from the beginning of the project for both planning and implementation of an ideally suited system.
An energy system of this type pays for itself within a short period of time thanks to reduced peak loads, exploitation of potential savings and simplified cost center billing procedures. An especially positive aspect for the customer results from potential savings which are guaranteed by the selected partner. The prerequisite for guaranteed potential savings is a precise analysis of the current situation, and customer implementation of prescribed corrective measures.
Practical Approaches to Energy Management
Practical approaches to energy management result from the implementation of an energy control system. The output signals from the measuring instruments which are generally read out as analog or pulse signals are processed and stored to memory by installing interlinked data loggers.
The user is able to access all data within the entire system from any point within the network. When selecting a data logging system of this type, it is quite advantageous from a cost standpoint to take advantage of the variable network structure included in the communications system which has already been installed in the plant. Values from physically distant summators or other operating locations can be retrieved by means of modem. The GOSSEN METRAWATT Energy Control System assures high data throughput for analysis and optimization, as well as short, load-shedding reaction times.
If an installed process control system should fail, the resulting energy effects can nevertheless be acquired and analyzed thanks to consistent isolation. The user, or an outside service supplier, can use this hardware platform for automatic billing of energy costs, for the optimization of consumption and peak loads, or for the representation of individual consumed energy quantities.
Tariff System Basics
A tariff is negotiated by the utility and the consumer, and energy is invoiced in accordance with the agreed upon conditions. In the simplest of all cases, only the quantity consumed is taken into consideration by this tariff, as is the case, for example, with water. Where electricity and gas are concerned, the amount of power made available is also taken into consideration. This relationship is described in detail below using electricity as an example.
Electrical energy tariffs include a kilowatt-hour rate and a demand rate. In order to bill peak loads to the user who has actually caused them, interval values must be stored to memory for lengthy periods of time. If this task is already accomplished by the existing system, the user only needs to read out and archive the respective data once per month.
After being confronted with this clear-cut substantiation of consumption, users are more than willing to looks for ways to reduce their peak loads and to implement appropriate measures. In the area of building management, peak loads can be avoided by means of reduced lighting, intermittent shutdown of air conditioning systems or activation of emergency power supply.
As an additional benefit, the energy management system relieves the energy department from the time consuming, cost intensive, error-ridden task of manually reading the meters at the end of each billing period. All meter readings can be accessed without delay from a single computer.
Cost center billing can be prepared automatically for all types of utilized energy media in consideration of various tariffs at the end of the billing period with the help of suitable analysis software. Plausibility checks recognize defective
meters, and values from commonly used meters are allocated to predefined cost
centers. The transmission of billing data to the company computer system is the basis for the billing of operating costs within the
The use of certified meters is recommended for the billing of energy costs to outside companies who rent space on the company grounds.
Complete Solutions from a Single Source
The implementation of complex systems of this type is a difficult task which generally exceeds the capabilities of the customer's plant staff, and it usually becomes apparent that the mere procurement of the required hardware and software does not lead to the desired success.