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General information
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Description
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Purpose
The installation of energy meters in railway vehicles facilitates the exact
measurements of energy consumption. This serves mainly two purposes:
- provide consumption data for an exact energy billing system
- provide consumption data for the identification and assessment of energy
saving measures
Availability of energy consumption data
In diesel traction the energy supply is on-board and therefore the energy
consumed can be clearly attributed to one single vehicle (nevertheless an
additional diesel flow meter can have an additional benefit). In contrast, in
electric systems energy consumption is usually measured at the substations only
which does not allow for an exact assignment to one single vehicle, since
several vehicles may be in the same feeding section.
As a consequence, energy billing is usually based on theoretical consumption
values derived from train data or simulations of train runs. The accuracy of
such a system is limited by various factors:
- Simulation algorithms are based on models that make simplified assumptions
on real conditions. This creates a small but non-negligible inaccuracy of the
outcome.
- Simulations or calculations do not take into account the specific external
factors influencing the energy consumption of one particular train run, such
as wind, track conditions etc.
- The same is true for internal factors influencing the train run, mainly
the driver. The driving style has a significant impact on energy consumption
through such factors as use of recuperation brakes, speed pattern and
coasting.
The values derived from direct measurements by means of an energy meter do
not have these limitations.
Liberalisation of railway markets
As European railway markets are deregulated, the energy consumption of
individual trains is no longer just an internal affair of the railway operator.
In an effort to ensure the same conditions for all competitors, a clear and
transparent billing mechanism has to be introduced. Naturally, an on-board
measurement of energy consumption is not a prerequisite for billing but it does
put it on a more accurate basis.
Technical details
There are no technical specifications for energy meters on a European or
international level, although there do exist standardisation efforts. An
on-board measurement of energy consumption and data recording as well as
processing requires the following system components:
- The energy meter: The energy measurement requires measurement transformers
(voltage and current) as well as the meter itself. The whole measurement
device usually has an accuracy of at least 2%. The measurement equipment must
be protected against manipulation by unauthorised persons.
- Data collection: Depending on the needs of the operator, the equipment
will produce ¼ hour or 1 hour profiles, i.e. the on-board equipment calculates
the energy consumed in a period of 15 or 60 minutes by integrating the power
intake over this period of time. Double registering allows for a separate
collection of energy intake and recovered energy returned to the grid.
- Data recording: A memory is needed to avoid data loss in case the regular
read-out is not possible. Usually, 60 days of data storage will in most cases
be sufficient.
- Remote reading: A remote reading by GSM or GSM-R radio link improves the
efficiency of the process.
- Display: There are controversial opinions on the question whether it is
desirable to display the consumed power to the driver. While some argue that
this could be an additional incentive to reduce energy consumption, others
fear that the additional information could distract the driver from more
relevant information.
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General criteria
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Status of development: in use |
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(no details available) |
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Time horizon for broad application: in < 2 years |
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(no details available) |
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Expected technological development: dynamic |
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Technological potential for the measurement equipment itself is rather low. However, the read-out process and the data processing still offer potential for further optimisation and automation. |
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Motivation:
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- Obtain an accurate basis for billing
- Get more transparency on energy consumption in order to identify and
assess energy saving measures
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Benefits (other than environmental): medium |
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Billing
The whole energy debiting process can be put on a more costs-by-cause
oriented basis.
LCC guarantees
The validity of LCC guarantees given by manufacturers can be confirmed or
disproven by means of energy meters. |
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Barriers: medium |
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Acceptance
If energy meters are not needed for billing purposes, operators tend to be
reluctant to invest into equipment not offering any obvious added value. SNCF
who operates in market not yet liberalised is sceptical about the benefits of
on-board energy measurement.
Technological
Presently no standard exists.
Retrofitting
Old vehicles often require tailored solutions.
Costs
Investment and maintenance costs can be high if a combination with
refurbishment measures is not possible or unrealistic.
Management & Organisation
If energy meters are introduced only as a feature in new stock and no
refitting is carried out, the fleet-wide roll-out may take several decades (~ 40
years). Experience from DB shows that great parts of the stock can be equipped
with energy meters within two or three years, if old stock is refurbished.
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Success factors:
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Standardisation and interoperability The different power supply systems may require corresponding interoperability efforts in some fields. A technological standardisation on a European level could accelerate technological development, create scale effects and improve planning reliability of manufacturers. Although a UIC standard is not a crucial prerequisite for introducing energy meters, common development efforts may be beneficial especially for small operators. However, a lengthy standardisation process could considerably delay the roll-out of energy meters. Economic Equip all new purchased trains with energy meters and use the already equipped part of the fleet to supply databases for improved calculations. Management & Organisation Be able to show the benefits from using energy meters and do not mix billing and energy saving targets. Furthermore, it has to be clearly defined, which data (e.g. measurement time intervals, train position, load situation ...) are needed to generate data basis for different saving measures. Acceptance The challenge of data reliability and automatic processing of data has to be tackled. |
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Applicability for railway segments: high |
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Type of traction: electric - DC, electric - AC
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Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight
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All electric vehicles can be equipped with energy meters. For diesel stock flow meters are an option. |
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Grade of diffusion into railway markets:
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Diffusion into relevant segment of fleet: < 5% |
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Share of newly purchased stock: < 20% |
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There are some applications in several countries. DB AG is currently equipping major parts of their fleet with energy meters. |
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Market potential (railways): high |
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Given the low degree of diffusion of energy meters and a growing demand, the market potential is very high in mid and long term perspective. |
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Example:
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The TEMA project at DB AG (TEMA=Traktions-Energie Messung und Abrechnung) In 2000 DB Energie tested the installation of energy meters in several trains as well as data transmission and evaluation in the TEMA project. The meters measure both energy intake and recuperation energy. At DB AG, energy metering is seen as an essential prerequisite for determining the influencing factors for energy consumption and monitoring the success of energy saving measures. Within the project different types of measuring devices tailored to individual vehicle series were installed and tested. The devices have a minimum accuracy of 2%. The system calculates and records 15 min consumption profiles. Remote reading via GSM is implemented. Following the projects, energy meters have now been incorporated into the specifications of new stock. A roll-out into the DB fleet is currently being realised. DB AG plans to introduce exact energy billing based on energy metering in 2003. Since energy meters are not a standard feature yet and competitors may continue operating stock not equipped with meters, billing based on metering is only offered as an option besides conventional billing. |
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Environmental criteria
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Impacts on energy efficiency:
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Energy efficiency potential for single vehicle: (no data) |
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Energy efficiency potential throughout fleet: (no data) |
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Energy meters have two positive effects on energy efficiency which presumably are both substantial but difficult to quantify: Economic incentive If energy billing is based on calculations, there is no economic incentive for operators to save energy by recuperation or energy efficient driving. Consumption data collected in the TEMA project at DB AG show that the energy consumption on a given line differs by up to 20% from one day to another. This underlines the role of factors such as weather, track conditions, traffic situation or driving style for energy consumption. These conditions are not taken into account by simulations presently used. Often, the calculated energy consumption is not even accurate enough to provide an incentive for using energy efficient stock. These shortcomings of theoretical consumption data obviously don’t apply to on-board energy measurements. Monitoring of energy saving measures Measuring or calculating energy consumption in itself does not save energy. However a better knowledge of energy consumption will provide valuable data to identify potential for optimisation as far as regenerative braking, energy efficient driving or stopping patterns are concerned. Experience at DB AG shows that energy meters facilitate the monitoring and thus tend to improve the general acceptance of energy saving measures within the company. |
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Other environmental impacts: neutral |
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(no details available) |
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Economic criteria
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Vehicle - fix costs: low |
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Retrofitting of fleet
Experience from the TEMA project at DB AG shows that retrofitting of old
vehicles with energy meters causes costs of about 2.000 € per vehicle.
New vehicles
In new stock the integration of an energy meter will be substantially cheaper
if the feature is contained in the specifications and can be integrated into the
vehicle design at an early stage. |
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Vehicle - running costs: (no data) |
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Energy consumption
Energy saving effects are to be expected but are rather indirect and will be
difficult to attribute to the existence of energy meters. |
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Infrastructure - fix costs: low |
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Infrastructure fix costs will be caused by required infrastructure (radio communication etc.) for remote reading and data processing. They will depend on the technological level of existing infrastructure, but will generally be moderate. |
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Infrastructure - running costs: unchanged |
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If remote reading is implemented and automated to a high degree and if an efficient data processing is in place, no major additional operation costs are created. |
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Scale effects: medium |
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(no details available) |
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Amortisation: (no data) |
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(no details available) |
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Application outside railway sector (this technology is railway specific)
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Overall rating
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Overall potential: very promising |
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Time horizon: short-term |
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Energy meters provide accurate energy consumption data of train runs. This is a very promising means to create an economic incentive for operators to save energy. At the same time, monitoring of energy saving measures is considerably improved. Experience from DB AG demonstrates that a quick roll-out is both technically and economically feasible. |