In addition of maximum service speed, train weight is the key parameter for metro train services and train aerodynamic resistance is the key parameter for long distance high speed train, which control the energy consumption of train.
Net energy consumption (Enet) of the train during the journey in allout mode may be classified in following areas:
1. Eaccel : Energy required from supply system to accelerate the train upto maximum service speed. Most of the energy taken during this period is stored in the form of kinetic energy of the train and a share of this stored energy may be returned to the supply system during the regenerative braking.
Eaccel ≈ (Effective mass of train * maximum achieved train speed2) / (2 * η )
Where η = Combined propulsion equipment efficiency
2. Erun : Energy required from the supply system to overcome running resistance (mechanical friction + air drag) during the journey. The energy needed to overcome the friction and air drag is converted finally into heat and can not be recovered.
Erun ≈ [ ∫ ( train resistance * train speed ) dt ] / η
3. Ecomfort : Energy needed from supply system for passenger comfort functions
Ecomfort ≈ ( train auxilliary load * jounery time ) / η
4. Ereg : Energy returned to the supply system during the regenerative braking
Ereg ≈ η * [ ∫ (regenerative braking effort * vehicle speed) dt ] ... during braking period only
Enet = Eaccel + Erun + Ecomfort - Ereg
When the service speed of the train is increased, the value of Eaccel increases in square of the speed. The value of Erun also increases because the value of train aerodynamic resistance increases in square of the speed and the term "vehicle speed * journey time" remains constant for given section. The value of Ecomfort reduces in the inverse of the speed. The value of Ereg increases from its previous value but the ratio of Ereg/Eaccel reduces with increase in the maximum service speed. It is concluded that when the service speed is increased, journey time is reduced but energy consumption of the train is increased. Increment in energy consumption mainly depend upon the maximum achieved speed, distance between stations, aerodynamic resistance of the train, weight of the train, regenerative braking capacity of the train, combined propulsion equipment efficiency, number of speed restrictions in the section and root profile of the section. Hence, rail operator may choose an appropriate maximum service speed of the train based on trade-off between consumed energy cost and journey time. Train operation at higher speed (200kmph or higher) is only beneficial when average distance between stoppages is around 100km or more and number of speed restrictions on track are minimum. Otherwise, a lot of energy will be wasted during frequent braking operations and effective saving in journey time due to higher speed will be ineffective.
Some technical papers explicate that high speed trains consume less energy per passenger-Km as compared to conventional trains. It may be possible due to the following reasons:
1. Route profile (i.e. Gradient, curve and speed restriction details) and number of train halt stations may differ for both types of the train.
2. High speed trains may be designed with improve aerodynamic profile to reduce train running resistance as compared to conventional running trains.
3. Generally high speed trains have tilting facility and thus can negotiate sharp curves without any speed reduction. However conventional trains have no tilting facility and thus apply frequent braking to reduce the speed for negotiating sharp curves. Frequent braking followed by acceleration in the conventional train increase the energy consumption.
4. Load factor, combined propulsion equipment efficiency, space utilization factor, auxiliary load and gross weight of both the trains may differ.
Solar Power System mainly consist of solar panels, battery bank and converter/inteverter unit. Solar panels / PV cells are made of semiconductor materials and they directly convert the sunlight falling on them to electrical energy. Battery bank is used to store this electrical energy. Inverter unit converts the battery DC voltage into AC voltage. Use of solar energy is also beneficial to our environment. Running cost of solar power system is mainly due to replacement of the battery bank after completion of its life. Life of battery depends on the number of charging and discharging cycle. Therefore, it would be preferable to use solar power system for generation of electrical energy where the requirement of electrical energy storage in battery bank is minimum. If most of the electrical energy developed by solar power system is being consumed in day time, then the running cost of solar power system can be reduced drastically. Solar power system will be most suitable if the nature of day time electric load is constant power. Electric loads of school, university, government offices, banks, post office, small factory, railway station, hospital, tunnel, malls etc. are most suitable in this regard. Solar panels installion on building roof observe the sun light and infrared rays and keep the roof of building cool, which indirectly reduce the power consumption of air-conditioning unit. Use of solar panel on roof of school and goverment offices will spread the awareness among new generation and public for use of renewable energy. In remote areas, solar power systems is a better option to fulfill the requirement of electrical energy. At the time of new constuction, roof of industrial shed should be made with suitable tilt angle, so if required in future, solar panels may be installed on the same shed easily with correct tilt angle. Proper cleaning of solar panels should be carried out at a regular interval.
This is appriciable that Indian Railway is promoting the use of green solar energy by installing the solar panel on the roof of railway station shed and office building etc. Recently, solar panel are also installed on the roof of coach on trial basis. Electrical energy developed by solar panels are used only for lighting and fan loads within the coaches. This will promote the use of green solar energy among the public. But, use of solar panels on roof of coaches have other drawbacks, which reduce the overall efficiency of the installed solar system. As we know that the solar panels give maximum electric power output when they are faced towards the Sun with correct tilt angle. Optimised tilt angle of solar panel depends on the latitude value of the place and month of the year. Therefore, tilt angle of solar panels should be optimized seasonally or monthly to obtain maximum output electrical energy from solar panels throught the year. Whereas, the tilt angle of solar panel installed on train roof can not be adjusted to optimum value because in this case, the tilt angle is governed by the curvature of the coach roof. Generally, two rows of the solar panels are installed on the curvature of coach roof. Due to this curvature, solar panels installed in both rows are tilted in opposite direction. Therefore, all solar panels installed on roof of coach can never make perfect angle w.r.t. Sun's rays and this reduces the overall efficiency of solar panels installed on train roof. In addition to this, installation of solar panels also increse the height and weight of the coach. Increased height of coaches increase the overall train resistance during operation due to more air resistance and therefore, indirectly energy/fuel consumption of locomotive/engine increases. Simultaneously, locomotive of train always consumes more energy/fuel to haul the extra weight of solar panels and its ancillary equipment from one station to another station. Therefore, effect of above factors should also be considered for calculation of overall efficiency of solar panel system installed on train roof. On the other hand, higher electrical energy can be developed by installing the same solar panels at optimum tilt angle on the roof of station building, plateform shed etc. Maintenance and cleaning of solar panel system installed on train roof is also difficult work.
Recently, electrical multiple unit concept based semi-high speed train is launched by Indian Railway with maximum service speed potential of 160 kmph. This train-18 has 50% motorized axles which provide higher acceleration in complete speed range, higher regeneration of electrical energy during braking and superior braking capacity. Train has superior passengers amenities i.e. fully air-conditioned coaches, attractive coach interiors, better ridding comfort, automatic door closing, passenger information system etc. Train-18 has advanced TCMS for smooth control and use three phase induction motor with IGBT based converter-inverter. Maximum power rating of Train-18 is more that 10MW during acceleration mode, which is equivalent to power of three locomotives. When train run at constant speed of 160 kmph, it consumes less power (approximate 5MW) as compared to power consumed during acceleration period. Initial cost of such type train is much higher than the locomotive hauled train. Higher initial cost of such type train may be recouped from the energy regenerated during braking. Metro rails also have higher acceleration in complete speed range and higher regeneration capacity during braking, which is prime requirement for train stopping at frequent interval. Therefore, the best utilization of higher regeneration capacity of such high power train can be availed if such type trains are operated for intercity services which stop and start frequently. For long intermediate station distance services, train operation with push-pull locomotives may be beneficial as compared to EMU based semi-high speed train due to its low initial cost and almost same journey time.
As a part of the Swachh Bharat Mission, Indian Railway had announced its aim of converting the entire rail route in the country into a waste discharge-free zone. Open toilets of coaches are being replaced with bio-toilet in entire coach fleet. Four bio-toilets are installed in each passenger coach. Each bio-toilet has approximate mass of 450kg. Therefore, total mass of coach is increased by 1800kg which is equivalent to mass of 24 passenger. Bio-toilets are environment friendly, preventing damages to tracks due to corrosion and improved aesthetics at railway stations. Anaerobic bacteria is added in the tank for degrading human waste. This bacteria can withstand sub-zero temperature as well as upto 60 degree centigrade. Cold temperature would not affect the insid e processing because anaerobic process is exothermic in nature thus; in cold regions, heat will be available inside the chamber because of chemical process. But, the bio-toilets have been prone to clogging due to the dumping of waste such as bottles, paper, pouches, cups and other material in the toilet pans, resulting in the foul smell. Approximately two litres of water is used while flushing the bio-toilet. Use of vaccuum toilets alongwith bio-degradable sewage tank have been introduced by Indian Railways in some trains to overcome these problems. Approximately half litre of water is used while flushing the vaccuum toilet. Vaccuum toilets also suck all smell. Therefore, design of bio-toilet tank may be reviewed to reduce its size and overall weight to save of energy indirectly.
The transportation industry of any country has a major role in the development of country economy. Practically, the transportation of freight for short
distances can be speedily and easily done be roadways; whereas for long distances, transportation by railway tracks are safe, fast, convenient and economical.
Transportation of freight through railway tracks provides huge petroleum-fuel saving because the value of rolling resistance of steel wheels on a steel rail is much smallar (1/5 to 1/6 times) than the
value of rolling resistance of rubber tires on a paved road. Even though rail is most efficient in carrying freight over long distances, roads have a lion’s share of total freight
transport because it offers greater flexibility in terms of final destination and volume of goods to be transported. The railways were losing their edge in freight transport
slowly due to well-developed road infrastructure in the country. This is a huge loss for
railways as freight is the main source of profit for them. As per the National Transport Development Policy Committee Report, in 2010 Railways’ share in freight traffic in
the country was estimated to be 36%. Considering transport requirement in the country and future vision of development; Dedicated Freight Corridor
Corporation of India (DFCCIL) was incorporated in October 2006. DFCCIL is a 'Special Purpose Vehicle' set up under the administrative control of Ministry of Railways to undertake planning & development, mobilization of
financial resources and construction, maintenance and operation of the Dedicated Freight Corridors. Further, in January 2018, Government of India has approved the concept of Golden
Quadrilateral Freight Corridor (GQFC), which has six Dedicated Freight Corridors (DFCs) rail tracks linking four largest metropolitan cities of Delhi, Mumbai,
Chennai and Kolkata and two diagonals North-South Dedicated Freight Corridor (Delhi-Chennai) and East-West Dedicated Freight Corridor (Kolkata-Mumbai). Out of six, two are
being implemented as Eastern Dedicated Freight Corrodor & Western Dedicated Freight Corridor respectively. Description of all six DFCs are given below:
Under implementation from 2006:
1. The Eastern Dedicated Freight Corridor with a route length of 1856 km consists of two distinct segments: an electrified double-track segment of 1409 km between Dankuni in West Bengal & Khurja in Uttar Pradesh and an electrified single-track segment of 447 km between Ludhiana (Dhandarikalan) - Khurja - Dadri in the state of Punjab, Haryana and Uttar Pradesh.
2. The Western Dedicated Freight Corridor covers a distance of 1504 km of double line electric (2 X 25 KV) track from Jawaharlal Nehru Port in Mumbai to Dadri in Uttar Pradesh via Vadodara-Ahmedabad-Palanpur-Phulera-Rewari.
Approved in January 2018:
3. East-West Dedicated Freight Corridor, 2,000 km-long from Kolkata to Mumbai
4. North-South Dedicated Freight Corridor, 2,173 km long from Delhi to Chennai
5. East Coast Dedicated Freight Corridor, 1,100 km long from Kharagpur to Vijayawada
6. South-West Dedicated Freight Corridor, 890 km-long from Chennai to Goa
Upgrading of transportation technology, increase in productivity and reduction in unit transportation cost are the focus areas for the above projects. DFC corridor has no level
crossings and uses one of the most advanced construction techniques to improve the quality and speed of construction. DFC aims to bring down the cost of freight transport using
electrical fuel, bigger and larger trains. This will help Indian industry to become competitive in the world export market. The other features of DFCs are given below:
1. Increased axle load upto 25 tonne with bridges and formation designed capacity of 32.5 tonne
2. Higher freight train speed of 100kmph as compared to existing freight train speed of 75kmph
3. Longer train length of 1500m as compared to existing freight train length of 700m
4. Train load of 13000 tonne as compared to existing train load of 5000 tonne
5. Double stack container operation with high rise OHE
6. Container width of 3600mm as compared to existing 3200mm width container
7. Adoption of 2*25 KV AT Feeding system to enable heavy haul operatioin with push-pull locomotives arrangement
Higher operational speed of DFCs allows operation of more trains on same route and hence result into fast transportation services, better line capacity utilization, reduced unit cost of transportation, rationalization of tariffs resulting in improvement in market share and improved operational margins. Further, Ro-Ro cargo services (Roll-on/roll-off of wheeled cargo such as trucks, semi-trailer trucks etc. on flat wagons) provide the best parts of both type of transport i.e. most of the booked distance is covered throught rail transport in minimum time and further, wheeled cargos are unloaded from flat wagons to deliver the freight by road transport. Konkan railway is the only railway zone in India, which has streamlined the Ro-Ro service and able to save 750 lakh litre diesel and related foreign exchange for the country. Eastern DFC may not be able to support RoRo as it has height of 5.1 meter compared to 7.1 meter of the Western DFC. Because of this only Western DFC may be able to support Ro-Ro services. There is an assumption of 15% increase in railway transportation within the next 15 years, which has been focused to reduce environmental pollution and encourage green transportation.
A freight train requires a lot of energy to accelerate from standstill to achieve maximum service speed and the same is stored in the form of its kinetic energy. When we stop a running freight train from its maximum service speed, its most of the kinetic energy has been wasted on wheel in the form of heat during braking. Simulation studies indicates that during the braking of a 5400tonne freight train from speed of 100kmph, the energy of approximate 600 KWh is wasted during friction braking. During the operation of train at maximum operational speed of 100kmph, energy is consumed to overcome the air and friction resistance. The energy requirement of 5400 tonne train at constant maximum speed of 100kmph is approximate 50 KWh/Km. Therefore, freight train can travel a distance of approximate 12 Km in the energy waseted during one braking from maximum speed. In the existing Indian Railway System, passenger trains have higher speed potential (130kmph or higher) as compared to freight trains (approximate 80kmph), which results into frequent stoppage of freight trains. This also increases the journey time of freight train drastically. Therefore, the energy consumption of Indian Railway drastically due to mixed operation of freight and passenger train on same track. After operation of DFCs, freight trains can be operated much efficiently with saving of lot of electrical energy as compared to existing Indian Railway Network. Therefore, a lot of petrolium oil can be saved with the operation of DFCs for which India is dependent to Gulf conutries. Time bound services of freight trains may also be provided easily which allow the transportation of food, green vegetables and other non-preservable items from one part of the country to another part of the country rapidly.
The newly dedicated freight corridors will once again give chance to railways to capture the freight transportation market and will play a leading role in the development of Indian economy. The seamless connectivity of passengers and goods will give the country an economic boost. Operation of DFCs shall reflect a drastic change in the transport sector and existing business opportunites.