Taking Charge of the Iron Horse

Electric mobility has grown massively all over the world in the past decade or so, spurred by multiple factors like increase in oil prices, environmental awareness about emissions and depleting fuel reserves, new technological developments in battery storage and drop in prices of associated equipment. In India, small battery-powered e-rickshaws were the first to gain some mainstream popularity, at least in the metros and some of the tier-2 cities. These were followed by electric 2-wheelers, then by cars and buses. Electric 2 wheelers are becoming more popular, and there are special incentives offered on purchase of electric cars. Some cities are conducting pilot studies on use of electric buses in their public transport system.

But one mode of transport which has been using electricity for several decades now is the railways. The commercial use of electrified railways grew rapidly from the 1890s to the 1920s. The first ever electric train in India ran in 1925. Over 300 km of lines in India already had electric traction at the time of independence. Steam still continued to operate on Indian tracks for several years, but was phased out for diesel, and then electric locomotives came into the picture. From the 90s onwards, electric locomotives had become quite mainstream, having come into use on some of the busiest sectors. With increasing traffic and with logistical factors such as time required for changing locomotives, some more routes were taken up for electrification. The gauge conversion project aims at converting most feasible non-broad gauge routes to broad gauge, and the converted routes are likely to become candidates for electrification at a later stage.

Since 2017 there has been significant increase in railway electrification activity, with recent annual figures recorded to be more than twice the figures immediately prior to 2017. 

A number of heavy traffic routes which until around 5 years ago were largely or entirely non-electrified have now gone under the wire. This includes two Rewari-Phulera routes (one of which goes via Jaipur) on the Delhi-Ahmedabad corridor, the complete Itarsi-Prayagraj (Allahabad) section on the busy Mumbai-Itarsi-Prayagraj-Patna-Howrah route, as well as sections of the Konkan Railway and Southwestern Railway. On the busy south-central region connecting Mumbai with Hyderabad, Chennai and Bengaluru, except for the small Solapur-Gulbarga stretch which is common to all these routes, the remainder is completely electrified. Double-stack goods trains operate on the Western and North-Western zones on routes connecting Delhi with the ports in Gujarat, and a Dedicated Freight Corridor has been set up here, complete with overhead wires at increased heights plus locomotives with specially designed high-rise pantographs, and has witnessed achievements like this 1.5 km long, electric-hauled double stack train.

Switching over to electric traction from diesel has cut down savings on fuel expenditure, and has reduced some dependence on imported crude oil (though there has been a dip in oil prices due to Covid-19), plus claims of reduction in direct pollution. In fact, the maximum electrification was achieved during 2020-21, with just over 6000 route km electrified and reported savings on diesel expenses close to Rs. 8000 crore. It should be kept in mind, however, that the decrease in operations of passenger trains may have also had some part to play in this reduction. For non-traction uses as well, a technology known as ‘Head-on generation’ has been employed where the electric locomotive hauling the train also provides power of the train, thus eliminating the need of attaching generator cars for providing power to the passenger coaches. This development has been claimed to save around 3000 litres of diesel per trip for some routes .

A proposal has been approved for electrification of over 13,000 route kms of track, at a total cost estimated to be around Rs. 12,000 crore. The Railways appear to be speeding towards the target of 100% electrification. This raises two questions:

1. What is being done to meet the increased demand for electricity?

2. What will happen to the diesel locomotives?

Regarding the second question, diesel locomotives will always be required in two cases: one is any emergency in which the supply to the traction wires gets cut off, and the other is when new track is being laid and there is no electrification there. Plus, as long as there are some non-electrified sections, diesel locomotives are going to be in use. In fact, there are some cases when trains cover the entire stretch with a diesel locomotive even when some large continuous parts of the route are electrified. So it is clear that the requirement of diesel locomotives is not going away.

The old ALCO (American Locomotive Company) diesel locomotives, the all-familiar ‘face’ of the Indian Railways, which have been around for several decades, are being phased out with more powerful GE-EMD (General Electric/Electromotive Diesels) manufactured locomotives which were introduced around 15 years ago.

ALCO locomotive (orange), EMD locomotive (blue and white)

(Source: https://www.travelerbase.com/index.php?proc=search&term=EMD%2520Vs%2520ALCo%2520INDIAN%2520RAILWAYS%2520Freight%2520Train%2520beauty&accel=1)

Some experiments have been conducted on locomotives. One experiment involved using the body of an ALCO locomotive and the internal parts of an old electric locomotive to create a new model, and it has been brought into use fairly recently. This locomotive is completely electric and has no diesel component in it.

WAG C3 locomotive

(Image source: https://commons.wikimedia.org/wiki/File:BNDM_WAGC3-WAG10.jpg JND AMD, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

In another experiment, which has wider reaching effects, a diesel locomotive was modified and fitted with a pantograph and other equipment used in electric locomotives, and converted into a dual-mode locomotive which can use the overhead wires in electrified sections and run on diesel in the non-electrified ones. This locomotive is the first one of its kind in India and is undergoing trials as of March 2021.

Now we come back to the first question about supplying sufficient electricity. It is expected that in 2023-24, if 100% electrification is achieved, then the annual traction electricity consumption would be around 33,000 GWh (3,300 crore units), which is more than twice the 15,540 GWh figure from 2013-14. The demand is expected to double to close to 4000 MW from the recent levels of around 2000 MW. It is interesting to note that the consumption figures which run into thousands of crores of units, are less than 2% of the total energy consumption in India.

Here is a chart comparing traction consumption with cumulative electrified length:

One possible reason why consumption has not increased at a comparable magnitude to electrified length may be the presence of unelectrified sections on largely electrified routes - because of this, often to save time, trains are operated with diesel locomotives even on long lengths of electrified sections.

The concept of regenerative braking has already been in use for several years to achieve a limited amount of energy conservation. The theory behind this method is that the traction motors can be made to work as generators for slowing down the train, and the energy recovered during this slowing down is fed back into the overhead traction lines, and can be utilized by nearby locomotives. This technique is applied when trains slow down near a station, or during the downhill journey of trains. The 3-phase locomotive models WAG-9, WAP-7 and WAP-5 which were introduced into Indian Railways in the late 1990s to early 2000s are all equipped with this feature, and have all demonstrated energy recovery to the extent of around 14%. This system has also been put into good use in the newer local trains (also known as electric multiple units or EMUs). Indian Railways is not the only beneficiary of this system; this system has been in use in Delhi Metro since the beginning of its operations, and in fact in 2007 Delhi Metro became the world’s first ever railway project to earn carbon credits for energy conservation through use of regenerative braking.

Regenerative braking, though useful, clearly has limitations. Providing sufficient generation and distribution infrastructure capacity is necessary to handle the increased demand due to growing use of electric traction.

For supply of electricity, Indian Railways is planning to turn to solar power in a big way, with a plan as of now to become carbon-neutral by 2030. Components of this scheme include using vacant Railways land and  Railways building rooftops for setting up solar power plants, which will provide power for both traction and non-traction use. It is targeted to install 20 GW of renewables generation capacity. A 1.75 MW solar power plant near Bina in Madhya Pradesh is connected directly to the traction supply system. As far as traction demand/capacity requirement is concerned, the total installed generating capacity of all non-renewable power generation utilities as of March 2021 is around 287 GW compared to the total expected increase in traction demand from 2 GW to 4 GW over a period of 2-3 years, during which it is also possible that other capacity enhancement projects might come into operation. The overall increase in demand is less than 1% of the total installed non-renewable power generation capacity, though at actual regional level this proportion will vary depending on existing power supply arrangements as well as how much increase in traction demand will occur. This will be a concern if the proportion of traction demand is too high because some backup capacity will be required in case the renewables do not produce sufficient output due to whatever reason, and might need a rethink of the scheduling and dispatch strategy.