REDUCING EMISSIONS FROM DIESEL-HAULED
COMMUTER TRAINS BY RECOUPING BRAKING ENERGY
Peter Eggleton
TELLIGENCE Group
Saint-Lambert, Quebec, CANADA
ABSTRACT
The concept of a hybrid braking energy recoupment system was defined for coaches of diesel-hauled regional commuter trains. Functional specifications were developed having the goal of increasing by 25 percent the acceleration rate of a commuter train consisting of 10 bi-level coaches hauled by a 3,000 hp diesel locomotive, typical of the rolling stock now in service in Canada and the U.S.A. Because increasing train acceleration was the primary aim, the concept was named the Hybrid Augmented Traction System (HATS). Analyses of HATS simulations showed that in addition to augmenting acceleration and reducing trip time, braking energy recoupment reduced fuel consumption and corresponding diesel emissions.
Examined were three alternate hybrid systems for train retardation by recoupment of braking energy, its storage and then regeneration based, respectively, on Hydrostatic, Battery and Ultracapacitor energy storage. The Ultracapacitor Hybrid system appeared the most promising due to the capability of ultracapacitors to repeatedly and rapidly accept large charges, be temperature insensitive and flexible in the placement of modules in the limited space available. The study foresees that HATS technology development could be expedited via the procurement process if railway operators specified braking energy recoupment requirements in calls-for-proposals for new capital equipment.
INTRODUCTION
A Hybrid Augmented Traction System (HATS) has been defined to recoup, store and regenerate the braking energy of individual coaches of locomotive-hauled heavy-rail commuter trains typical of those in use in Canada and U.S.A. Fig. 1 shows a typical such train as operated by GO Transit which serves the Toronto-centered region of Ontario, Canada. Since traffic is increasing, operators would like to increase throughput by raising the acceleration of such diesel-hauled trains when
departing stations, while at the same time stemming the rise in fuel consumption and exhaust emissions.
Figure 1 Diesel Locomotive-hauled Commuter Train Examined and compared were three hybrid augmented traction arrangements that could be fitted to the trucks (bogies) of each of the coaches to capture and then regenerate the train braking energy so as to supplement the tractive effort of the hauling locomotive. The alternate hybrid arrangements examined were:
Battery Hybrid
(electric generator / battery storage / electric motor)
Hydrostatic Hybrid
(hydraulic pump / hydrostatic storage / hydraulic motor) Ultracapacitor Hybrid
(electric generator / ultracapacitor storage / electric motor) BACKGROUND
Canadian commuter railways transported 66 million passengers in 2009, which over the last decade have increased at an annual rate of 5.5 percent [1]. Diesel fuel consumption in 2009 for the three locomotive-hauled commuter operations in Proceedings of the ASME 2012 Internal Combustion Engine Division Spring Technical Conference ICES2012 May 6-9, 2012, Torino, Piemonte, Italy
ICES2012-81146
Canada totaled 42.7 million litres, producing 131,500 tonnes of greenhouse gases and 2,815 tonnes of criteria air contaminants. To handle the rising commuter traffic yet stem the rise in fuel consumption, emissions and wear and tear on equipment, operators are looking for ways to increase throughput capacity while maintaining service reliability and safety. One way to increase commuter system throughput capacity is to increase train acceleration out of stations. This is generally accomplished by adding a second locomotive. However, a second locomotive leads to concomitant increases in fuel consumption, emissions and capital and maintenance costs. An alternative is to recoup the braking energy of individual coaches and then regenerate that energy to supplement the tractive effort of the hauling locomotive so as to augment train acceleration and avoid the necessity of a second locomotive. The frequent stop-and go commuter train operations are particularly energy intensive both in terms of maximum locomotive power required during acceleration and high braking effort being applied soon afterwards, the energy from which is currently dissipated as heat from the coach brake components and grids of the locomotive’s dynamic brake. To effect the available energy recoupment and its regeneration, the trucks of each coach could be fitted with HATS drive technology. Fig.2 shows the axles and frame of a typical coach truck onto which HATS components could be mounted.
Figure 2 Coach Truck Showing Axles for Mounting HATS Technology
IDENTIFYING ALTERNATIVE HATS TECHNOLOGIES To initiate the study, hybrid drive developments underway in the automotive sector were identified and examined, particularly those technologies currently being developed for heavy-duty stop-and-go vehicles such as garbage trucks and container lift cranes. Regardless of the technology, the basic configuration consists of an energy recoupment component, an
energy storage component and an energy regeneration component. Three alternative technologies were selected for their applicability to a railway coach truck. Each technology is characterized primarily by its method of energy storage, that is, either by chemical battery electrical charge (Battery Hybrid), hydrostatic oil pressure (Hydrostatic Hybrid) or electrostatic charge (Ultracapacitor Hybrid). Flywheel kinetic energy storage was judged not an option due to its inherent mechanical installation complexity and, despite considerable railway application attempts in the past, none has been successful in overcoming performance, reliability and installation cost issues. The block diagrams for the above-listed alternative HATS component arrangements are schematically illustrated in Fig. 3, 4 and 5.
Figure 3 Battery Hybrid Components Arrangement
Figure 4 Hydrostatic Hybrid Components Arrangement
Figure 5 Ultracapacitor Hybrid Components Arrangement HATS APPLICATION TO COMMUTER TRAINS
Commuter Train Operational Particulars
Locomotive-hauled commuter trains are characterized by their frequent stop-and go operations. These operations are particularly energy intensive both in terms of maximum locomotive power applied during acceleration followed by high braking effort being applied soon afterwards. Such highly
cyclic operations are illustrated in an extract from a GO Transit locomotive event recorder read-out, as shown in Fig. 6 [2]. The top curve is a read-out of train speed, with the zero speed (flat areas) indicating station stops. The lower curve is a read-out of locomotive throttle notch position, with N-1 being idle and N-8 being maximum power. One can see that in most instances of train acceleration, N-8 is activated. Train deceleration rate appears higher than acceleration.
Figure 6 Graphical Trace of Throttle Position and Train Speed versus Time
Similarly, analysis of the duty cycle of commuter trains shows that the locomotives average 25.8 percent of their operating time at maximum power (N-8), 61.5 percent at idle and only small amounts of time at intermediate power levels, as indicated in Table 2.
Table 2 Duty Cycle of Commuter Train Locomotives
Commuter Train Acceleration Performance
A typical train operating on a Canadian heavy-rail commuter service, as illustrated in Fig. 1, consists of one diesel locomotive hauling up to ten coaches. The largest fleet, GO Transit, operates diesel-powered EMD F59PH locomotives weighing 118 tonnes and producing 3,000 HP for traction hauling Bombardier bi-level coaches as shown in Fig. 7 weighing 63.6 tonnes each [3]. The total weight of a ten-coach train (less passengers) is of the order of 754 tonnes. With 133 seated passengers weighing an average of 68 kg each, the ten-coach train can have a total weight of 845 tonnes.
Figure 7 General Arrangement of Bombardier Bi-Level Coach
The measured acceleration performance of such a train is shown in Fig. 8 [4]. It is, thus, this performance that is to be augmented by the application of HATS technology.
Figure 8 Acceleration Performance of Typical Commuter Train
Kinetic Energy Available for Recoupment
In estimating the kinetic energy of the train during braking for a station stop, a deceleration rate of 1 metre/sec 2 (0.1 g) continuous was assumed. This is the maximum deceleration rate that standing passengers can withstand without feeling unsteady. It should be noted that the maximum braking rate of the train is specified as 1.5 mph/second (0.67 metre/sec 2).
Based on a total train weight of 845 tonnes, the calculated maximum theoretical kinetic energy that could be recouped when braking from 100 km/hr (62 mph) is of the order of 280 MJ. This is equivalent to 78 kW-hr, or equivalent to 1,560 kW of power if all of this energy were drawn down for 3 minutes of train acceleration. Spread over 10 coaches, the power available per coach would be 156 kW over 3 minutes. This suggests one traction motor of up to 75 kW could be fitted to each of the two coach trucks.
Augmented Performance Goals with HATS
To size the HATS components, an acceleration performance augmentation of 25 percent over that shown in Fig. 8 was selected. For example, a speed of 50 km/hr (31 mph) would be reached in 45 seconds instead of 60 seconds. It is estimated that the augmented acceleration could be sustained for approximately three minutes from stop based on the estimated amount of energy able to be recouped and stored. Fig. 9 displays the HATS augmented acceleration performance relative to the baseline performance of one F59PH locomotive hauling ten bilevel commuter coaches.
MPH
TIME - MINUTES
Figure 9 Augmented Acceleration with HATS Technology FUNCTIONAL SPECIFICATIONS FOR HATS
Listed hereafter are the targeted specifications guiding the conceptual definition of HATS technology for application to a diesel-hauled commuter train:
Performance Augmentation: Train acceleration to be 25 percent higher than baseline configuration of one F59PH locomotive hauling 10 coaches. For example, the time to reach 50 km/hr would reduce from 60 to 45 seconds;
Motorization of Existing Truck: For augmented acceleration performance, one 50 kW motor-generator or equivalent hydraulic motor-pump unit installed per truck (two per coach). Unit to be mounted on axle stub outboard of wheel on opposite side to which, similarly, the outboard disc brake is mounted; Autonomous Configuration: All constituent HATS components to be contained within the envelope of coach truck, with minimum on the coach body, if possible;
Interchangeable with Baseline Design: HATS-equipped trucks can be interchanged with baseline configuration trucks for any coach variant;
Retrofit of Existing Truck: HATS components to be add-ons to existing coach truck with minimal structural modifications (rather than requiring a new truck design);
Operational Control: System to be inter-operable with existing locomotive throttle control for acceleration and blended disc/tread wheel and dynamic braking systems for deceleration, and not require additional crew input for system operation. Input signal from brake pipe pressure and connection into trainline;
Dimensional Adherence: HATS-equipped trucks to respect clearances and loading gauge specified by AAR and Canadian railway safety regulatory authorities;
Structural Integrity: Truck-mounted HATS package to be designed to withstand track-induced vibration forces and buff shocks typical of those experienced in railway operations; Modular Design: To facilitate retrofit, in-service maintenance and change-outs, a modular ‘form, fit and function’ design philosophy to be followed;
Mounting of Energy Storage Devices: To be packaged and supported so as to fit within the side bolsters both between and ahead of axles, if possible;
Reliability Target: Mean-time-between-failure (MTBF) to be greater than 200,000 hours (approximately 7 - 10 years between coach refurbishing);
Availability: Greater than 95 percent; Ambient Operating Conditions:
Temperature: Minus 40 0C to Plus 40 0C Relative Humidity: 20 % to 40 %
Rain: 3 cm / hour or 10 cm / day Snow: 5 cm / hour or 30 cm / day Freezing Rain: 1.25 cm / hour or 5 cm / day
IDENTIFICATION OF HATS DRIVE ARRANGEMENTS The first challenge in retrofitting HATS technology onto the existing coach truck was to identify the drive arrangement – particularly in regard to minimizing requirement for new components, complexity and alterations to major components such as the axle. For the HATS electric motor-generator arrangement, various existing configurations were examined – namely axle-hung traction motors, frame-hung traction motors or use of a drive shaft with bevel gearing on the axle. Although these are service proven, an alternate arrangement to overcome their retrofit complexity (and space needed within the truck frame) could be to affix a pancake electric motor-generator onto the outboard stub of an axle, as envisaged in the sketch in Fig.10. Bolting of the motor armature onto the axle stub would be similar to how the outboard disc brake is already fitted onto the opposite end of the truck axle. The retardation and driving input forces are judged to be of a similar order of magnitude. To overcome the relative motion between the axle and truck side frame, the motor casing (with field windings could be mounted on a bearing also fitted on the axle stub outboard of the wheel, supported by brackets and stays bolted to the side frame. This way, there would be no relative motion between the motor armature and outer casing retaining the field windings.
Figure 10 Proposed HATS Drive Retrofit Mounting Arrangement
`
The phantom outline in Fig. 10 is a schematic of a possible energy storage cabinet arrangement containing the battery pack or ultracapacitor modules.
ESTABLISHING BASELINE PERFORMANCE SPECIFICATIONS
Based on the functional specifications listed and the general configuration envisaged in Figure 10 for a HATS-equipped
truck, the principal energy storage and traction components can be sized using the following input assumptions:
- 1 HATS device per truck - 2 trucks per coach
- 10 coaches (20 trucks) per trainset
- 1 EMD F59PH locomotive providing a maximum traction force of 300 kN (67 klbf)
The performance goal for HATS is to add 25 percent to the acceleration of the train. Assuming the maximum tractive effort operational mode for the locomotive, the additional effort provided by HATS is then 25 percent of 300 kN = 75 kN. Spread evenly on the 20 trucks of the 10 coaches, the additional tractive effort per truck amounts to:
75 kN ÷ 20 = 3.75 kN (843 lbf).
If we assume that the tractive effort can be sustained by the trainset up to 30 mph (48 km/h or 13.4 m/s), this requires a power of 3.75 kN x 13.4 m/s = 50 kW (67 HP) per device. Once at that level of power, the trainset will continue to accelerate with that tractive effort following the equipotential effort versus speed curve.
Assuming that the augmented acceleration requires this power (50 kW) to be applied per truck for four minutes (240 seconds) and that a storage buffer, especially for battery or ultracapacitor options, of 25 percent of maximum energy storage capacity is maintained, then the energy needed during acceleration is 50 kW x 240 s = 12 MJ (3.33 kWh). Adding a buffer of 25 percent, that is, 3 MJ (0.833 kWh) results in a minimum energy storage capacity per acceleration cycle of 15 MJ (4.17 kWh).
However, for practical contingency purposes the system should be designed to achieve three acceleration cycles in a row before being recharged, resulting in a required energy storage rating of 3 x 15 MJ = 45 MJ (13 kWh).
Based on the above calculations, the baseline performance specifications for the HATS energy storage and traction components for each truck are displayed in Table 3.
Table 3 Baseline Specifications for HATS Components (per truck)
IDENTIFICATION AND SIZING OF CANDIDATE ENERGY STORAGE COMPONENTS
As indicated on Table 3, the targeted storage capacity per HATS-equipped truck is 13 kWh. The storage capacity particulars of several proprietary storage technology systems were examined, with candidates selected for follow-on study. Batteries
Batteries of the type required for a HATS application would be those that can be recharged from the electrical current generated by the braking kinetic energy. Many new battery chemistry combinations are being investigated and characterized, stimulated by ongoing research to develop batteries for electric and hybrid automobiles [5]. The preferred battery type for a HATS application should have as high an energy density and cell voltage as possible with a low self-discharge rate. Currently, a lithium-ion battery pack appears best to fill this requirement. Fig. 11 shows such an example.
Figure 12 Lithium-ion Storage Battery Pack (Illustration Source: Mercedes-Benz 2010 Hybrid) Ultracapacitors
In ultracapacitors, energy is stored electro-statically at an electrode-electrolyte interface [6]. Compared to batteries, ultracapacitors have one-tenth the energy but deliver approximately 10 times the power. Ultracapacitors, in contrast with conventional capacitors, possess high capacitance per unit of volume because their electrodes have a larger surface area per unit of volume and the separation between the electrodes is much smaller. As shown in Fig. 13, ultracapacitor cells can be assembled into packs or modules (in series or parallel connections) for the performance needed.
Like battery technology, ultracapacitor technology is advancing rapidly spurred by ongoing research for applications
in the automotive and electrical grid uninterruptable power supply sectors. The attractiveness of ultracapacitors as an energy storage medium is their ability to charge and discharge rapidly and without deterioration, regardless of ambient temperatures (which is a shortfall in chemical battery performance). The round-trip (in-out) efficiency is very high (up to 95 percent), but the self-discharge rate is considerable compared with batteries. The lifetime number of charge and discharge cycles is, for all practical purposes, nearly unlimited. They are characterized by a high energy charge density (kWh / kg) per cell, a low voltage (approximately 2.7 V per cell), and a high power output (up to 1 kW) but for a short energy storage time (a few minutes).
Figure 13 Example of an Ultracapacitor Module Due to their ability to absorb the large transient charge and discharge rates experienced during the frequent braking and acceleration of a commuter train, ultracapacitors are envisaged an appropriate storage medium for a HATS application. They offer a design option where high power is required for a relatively short duration, thus accommodating the limited energy content characteristic of capacitors [7].
Hydrostatic Accumulators
The hydrostatic hybrid option examined for HATS technology is a hydraulic system wherein mechanical energy (from retarding the train) is converted into oil stored under high-pressure in bladder-type accumulators (storage vessels) that can be subsequently released and re-converted into mechanical energy to accelerate the train. The basic concept is that just as an electric traction motor can switch from working as a generator to that of a motor, the hydrostatic system uses a reversible high-pressure hydraulic axial pump-motor unit that can alternate between being a pump (generator) and a traction motor. Hydraulic oil, pressurized when the pump / motor unit
operates as a pump during the train braking retardation process, is hydrostatically ‘accumulated’ up to 5,000 psi pressure in a nitrogen gas filled bladder-type storage vessel (accumulator).
The hydrostatic (pressurized) oil can then be released in a controlled manner to energize the hydraulic pump-motor unit to, in turn, operate as a motor to accelerate the train. An example of such a concept using bladder-type accumulator vessels, as illustrated in Fig. 14, is the Bosch Rexroth Hydrostatic Regenerative Braking System developed for garbage trucks which experience frequent stop and go, heavy-duty service [8].
Figure 14 Schema of Bosch Rexroth Hydrostatic System Further consideration of the hydrostatic option was suspended following analysis by a supplier of hydrostatic regenerative braking systems, Bosch Rexroth Corporation, that the accumulator capacity needed to capture the kinetic energy of a commuter train coach when braking is beyond the space available to fit it, be it on the truck or coach – plus the development effort incremental to the current equipment design deployed in hybrid hydrostatic drive heavy-duty garbage trucks would be too costly to justify for the commuter railcar market. IDENTIFICATION OF MOTOR--GENERATOR DRIVES The HATS function is based on converting the kinetic energy generated while braking into direct current (DC) electrical energy and storing it for subsequent release to augment starting and accelerating the train. The stored energy is released via a DC-to-AC convertor to a truck mounted alternating current (AC) motor-generator drive, which now operates in traction motor mode. In identifying traction motor-generator configurations with particulars to match the HATS functional and performance specifications and with the preferred outboard ‘pancake drive’ mounting configuration, it was assumed that the power source for traction be integral with the generator that recoups the train retardation kinetic energy that is subsequently stored for regeneration. Also, an underlying assumption is that the configuration identified should require a minimum of re-design and engineering development for a HATS application. Hence, priority is given to identifying available hybrid motor-generator technologies
transferable to HATS’ applications. One such motor-generator drive having the above-listed characteristics and also of the preferred compact ‘pancake’ design configuration is offered by the German company, Heinzemann GmbH. It is currently applied to hybrid diesel engine / electric drives used in fork lift and back-hoe industrial equipment. A 50 kW unit is displayed in Fig.15 below.
Figure 15 Heinzemann GmbH Pancake Motor For the HATS alternatives based on battery or ultracapacitor energy storage, the initial examination focused on AC electric motor-generator technology. This reflects the trend in automotive hybrid drives which are primarily AC-based because they tend to be lighter in weight and more robust. Alternatively, as DC propulsion tends to be more common with railway operators and generally has a simpler control circuit, the motor-generator drive could be DC based, if suitable technology were to be found to be available.
HATS SIMULATION IN AN ACTUAL COMMUTER TRAIN OPERATION
In order to gain an appreciation of the impact on operations of a HATS-equipped train, a Train Performance Calculator (TPC) simulation was made of the GO Transit commuter run from Burlington to Oshawa via Toronto’s Union railway station [9]. The current scheduled time for the 101.5 km Burlington to Oshawa run is 1:37:38 hours in which there are 18 station stops. The purpose of a TPC is to calculate trip time and fuel consumption for different train consists and operating conditions. In order to match the parameters of a HATS-equipped train to the TPC computer simulation, the traction motor on each HATS truck had to be considered a ‘mini-locomotive’ of 50 kW power. Thus for the TPC simulation, the trainset became 10 bilevel coaches hauled by one F59PH diesel locomotive of 2,237 kW (3,000 hp) plus 20 mini-locomotives of 50 kW each.
Fig. 16 shows the TPC trace of speed on a base of elapsed time. The left side of each spike is the acceleration from station stop, while the more abrupt right side of each spike is the deceleration to station stop. Fig. 17 shows a printout of
acceleration / deceleration rates versus elapsed time from start of run.
Figure 16 Simulation of Speed versus Elapsed Time
Figure 17 Simulation of Acceleration Rate vs. Elapsed Time
As listed in Table 4, five trainset configurations were subjected to TPC simulation runs: Simulation Run No.1 being the existing configuration (as baseline for comparisons) and Simulation Runs No.2 to No. 5 being ‘augmented traction’ configurations.
Table 4 TPC Simulation of Five Commuter Trainset Configurations
The first of the augmented traction simulations (Run No.2) was for a double-locomotive consist, that is, two F59PH locomotives hauling 10 bilevel coaches, while the remaining three simulations had one F59PH locomotive hauling 10 bilevel coaches, each of which outfitted with HATS trucks having, respectively, traction motors of 50, 75 and 100 kW each. The reason for simulating a double consist having two F59PH locomotives was to quantify the augmented acceleration that could be obtained right away, if opted for by the operator. The two-locomotive case then became the baseline reference against
which the costs versus benefits of a HATS-equipped trainset could be compared (as HATS could obviate the need for a second locomotive).
Impact on Trip Time
The TPC simulations showed that train acceleration did increase and trip time decreased for the four augmented traction cases. In Fig. 18, the calculated trip times for the maximum speed mode are displayed for the different train configurations as listed in Table 4. The trip time for the baseline reference trainset is 1:37:38 hours whereas the same train with two locomotives is 1:24:30 hours. Of note is that the train with 50 kW HATS-equipped trucks is only marginally slower at 1:25:32 hours. The times for trains with 75 kW and 100 kW HATS-equipped trucks are, respectively, 1:22:51 and 1:20:30 hours.
Figure 18 Travel Time Simulation of Five Trainset Configurations
Impact on Fuel Consumption
As mentioned, the principal TPC calculations are for trip time and fuel consumption. However, the calculation in the TPC simulation for fuel consumption was inconsistent for analyzing HATS cases. This is because the TPC calculates fuel consumed as a function of locomotive power output. Thus, the TPC simulation calculated fuel consumption for each of the 20 HATS traction motors as if they were diesel locomotives consuming fuel. This wrongly showed on printouts that HATS-equipped trains consume proportionately more fuel. To overcome this miss-statement, a correction factor is required to adjust the fuel consumption calculated for the HATS-equipped cases. For example, whereas the fuel consumption for a train equipped with 50 kW HATS units (total power of 2,237 kW + 1,000 kW) was calculated by the TPC to be 825 litres (L), in reality only the F59PH locomotive is consuming fuel to produce up to 2,237 kW power (which corresponds to 660 L for the Burlington to Oshawa trip case).
Fig. 19 shows the printout for fuel consumption for the minimum running time case with correction factors applied (green area) showing the HATS impact. The red line indicates the amount of fuel actually consumed by the diesel locomotive for each simulation case. To establish the correction factors for the HATS cases, it was assumed that to accelerate the train, the locomotive would be at rated N8 power level (as done, at present) plus be augmented by the HATS units. However, because the HATS-equipped train now reaches track speed sooner (at which time the locomotive is throttled back to a coasting mode), it will use less fuel to cover the 101 km Burlington to Oshawa run. The correction factor for the reduced amount of fuel consumed was considered to be the ratio of the trip times with and without HATS units. For example, for the 50 kW HATS case, the correction factor relative to the baseline (no HATS) fuel consumption case is: 1:25:32 hr (85.53 min) ÷ 1:37:38 hr (97.63 min) = 0.88 The factors for 75 kW and 100kW cases are 0.85 and 0.83. The fuel consumption for the 50 kW HATS-equipped trainset is 660 x 0.88 = 581 L. Compared with the baseline no-HATS configuration, this is a reduction of 12 percent.
Figure 19 Fuel Consumption Simulation of Five Trainset Configurations
As noted in Fig. 18, the 50 kW per truck HATS-equipped trainset provides almost the same trip time as that of a trainset powered by two locomotives. However, the fuel consumption is 581 L versus 1,013 L for the two-locomotive no HATS case, a reduction of 42.6 percent for effectively the same trip time. Impact on Diesel Exhaust Emissions
There is a direct correlation between reduced fuel consumption and reduced emissions from the locomotive’s diesel engine. The combustion of one litre of diesel fuel produces 3.00715 kilograms of Greenhouse Gases (GHG) measured as CO2 equivalent and 58.46 grams of Oxides of
Nitrogen (NOx), plus 5.78 grams of other Criteria Air Contaminants (CAC) such as Hydrocarbons (HC), Carbon Monoxide (CO), Particulate Matter (PM) and Oxides of
Sulphur (SOx) [1]. GHG emissions are contributing to global warming and climate change while CAC emissions are harmful to human health and the ecology.
As an indicator of HATS technology to reduce diesel exhaust emissions, in 2009 the commuter railways in Canada consumed 42.7 million litres of diesel fuel, producing 131,500 tonnes of GHG and 2,815 tonnes of CAC emissions. If HATS units were to be deployed in all fleets, the resulting estimated 12 percent reduction would lower the GHG emissions by 15,780 tonnes and the CAC emissions by 338 tonnes.
RETURN ON INVESTMENT BENEFITS
From an operations viewpoint, deployment of HATS-equipped trainsets on a commuter railway has the potential to:
• provide a higher acceleration rate concomitant with a 12 percent reduction in fuel consumption and diesel exhaust emissions levels;
• obviate the need for a second locomotive to otherwise attain a similar augmented acceleration rate;
• increase the passenger throughput per day with shorter trip times with existing fleet size;
• reduce wear on mechanical disc and tread brakes. The following analysis attempts to quantify, in financial terms, a return on investment (ROI) from the above-listed attributes. If the cost / benefit outcome is positive, it could provide the motivating collateral to substantiate a commitment for the development of HATS technology. Although establishment of detailed cost estimates for a full HATS development program is beyond the scope of a conceptual definition study, what can be estimated are the order-of-magnitude costs of alternate methods to augment the acceleration rate, increase throughput, reduce trip time and reduce fuel consumption and emissions using the existing trainsets.
On a high-capacity commuter line, the straight-forward way to achieve an augmented acceleration rate, at present, is to deploy a ‘second locomotive’ on the trainset. The capital cost of commuter train locomotives is of the order of $5 million each plus an annual cost estimated at $50,000 for servicing and maintenance. If the need, for example, for three ‘second locomotives’ could be obviated by three HATS-equipped trainsets, the capital cost avoided would be 3 x $5 million = $15 million plus $150,000 in annual operating costs.
If the $15 million avoided acquisition cost could be re-allocated to the development and acquisition of HATS retrofitted trucks for, say, 10 trainsets consisting of 200 coaches with 400 trucks, and allowing $1 million for a prototype development and testing program, then the incremental acquisition cost allowable per HATS-equipped truck could be: $15 million - $1 million = $14 million ÷ 400 = $35,000.
By avoiding the ‘second locomotive’ and outfitting a trainset with HATS technology, as illustrated by the TPC simulations for the GO Transit Burlington – Oshawa run, the fuel consumption avoided per trip would be 1,013 – (660 x 0.88) = 432 L of diesel fuel. For six round trips per day, this totals 6 x 2 x 432 = 5,184 L per trainset. For three trainsets, the fuel saving per day is 3 x 5,184 = 15,552 L or, on annual basis of 300 work days the fuel saving is 300 x 15,552 = 4,665,600 L (worth approximately $5 million).
Various alternate cost estimating scenarios could be made based on the total market potential for HATS-retrofitted trucks. In North America, there are approximately 700 bilevel coaches of the type manufactured in Canada in operation on 13 railways. Also, there are bilevel coach types from other manufacturers for a total estimated market of 1,000 coaches. This market potential for 2,000 HATS-equipped trucks would appear sufficient for a manufacturer to realize a positive ROI. HATS DEVELOPMENT SCENARIO
The innovation cycle as it relates to the realization of new or improved technology used in transportation is characterized by distinct progressive stages, commonly referred to as the ‘5Ds’ of the innovation cycle [10]:
D
EFINITIOND
ESIGND
EVELOPMENT
D
EMONSTRATION
D
EPLOYMENT In a rudimentary way, the ‘5Ds’ cover the whole gamut from when a concept is first ‘DEFINED’ against a known need or opportunity, through its detailed ‘DESIGN’ leading to the building of a first prototype (or experimental model), the testing and further ‘DEVELOPMENT’ or perfecting of the prototype, its ‘DEMONSTRATION’ in pseudo revenue service or on a test track of, generally, a small (pre-series) quantity which provides the basis for deciding whether to commit to its ‘DEPLOYMENT’ in daily revenue service. All transportation development projects follow, more or less, the 5Ds process. In order to bring HATS technology from the idea stage to operational deployment, it is envisaged that a similar ‘5Ds’ process would be followed, starting with the conceptual definition stage (as initiated by this study) through to final deployment in revenue service on a diesel locomotive-hauled commuter train. The lead time in transportation technology development is long. The better part of a decade generally passes before a concept is developed to the stage of operational deployment. It is then often another three to five years before it can be evaluated explicitly as to whether the new technology has yielded improvements. A very complex process (i.e., the 5Ds) is followed to attain this stage – but this is how innovations in transportation come about.Using the Capital Equipment Procurement Process to Expedite Development of a HATS-Retrofitted Truck It is well known that the technology innovation process is facilitated if the ‘technology push’ from the designer is combined with ‘technology pull’ from a potential user. The involvement of an end-user transportation operator in the innovation process not only facilitates the designer to establish relevant specifications but also gives visibility to a potential market that, in turn, yields useful collateral when, for example, technical input and priorities are sought from component suppliers or funding is sought from public or private agencies supporting research and development. Involvement of an end-user operator in the 5Ds innovation cycle also helps overcome the ‘valley of death’, that is, the Development and Demonstration stages wherein many projects fail due to underestimation of the problems and / or resources needed. Having said this, it is a reality that commuter train operators rarely have the mandate or in-house technical staff to undertake the development work. A strategy around this constraint is to use the procurement process for new rolling stock capital equipment to promulgate requirements for new component technology. In this way, the operator purchasing the rolling stock puts the onus on the original equipment manufacturer (OEM) to be accountable to develop new technology (such as, for example, a HATS-equipped truck) in the course of delivering, for example, new or remanufactured coaches. By including this requirement in the procurement call-for-proposal inherently identifies the market for the new technology, thus providing the collateral and spur for the OEM to initiate the ‘5D’ stages to perfect the HATS technology. It also facilitates the compliance with safety standards and regulatory norms. CONCLUSION
The concept of a HATS-equipped coach truck has been defined whereby braking energy is recouped, stored and regenerated to augment the acceleration of diesel locomotive-hauled commuter trains. The initial analyses indicated that for a 25 percent increase in acceleration of a diesel locomotive-hauled 10 coach trainset that one 50 kW axle-mounted motor-generator per truck energized by Ultracapacitor storage cells is the preferable option. Corresponding benefits are reductions in fuel consumption and diesel emissions by 12 percent. A strategy foreseen for expediting the development and deployment of HATS technology is for a commuter railway operator to specify HATS as an element of the trainset capital equipment procurement process. This strategy inherently creates a market for HATS and expedites innovation.
ACKNOWLEDGEMENTS
To undertake the study, the author acknowledges with appreciation the encouragement and data provided by GO Transit, as well as the funding and project orientation provided by Transport Canada’s Transportation Development Centre.
REFERENCES
1. Locomotive Emissions Monitoring Program 2009, Report published by the Railway Association of Canada, Ottawa, November 2011
2. Eggleton, P., Dunn, R., Duty Cycle Profile of 2007 Canadian
Diesel Locomotive Fleet. Report prepared for the Railway
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