India has to work out a ‘cleaner’ approach to Auto LNG, by locally developing renewable gas.
Europe is already surging ahead with Liquefied Natural Gas (LNG) or Biogas (renewable natural gas) for commercial vehicles. In India too, a lot of action is taking place in the LNG scene. Just last August, Union Government has notified revised gas cylinder norms for LNG stations, which is aimed to help establish a storage and supply chain for refueling stations through ‘daughter trucks’, just like for CNG stations in Delhi.
Home-grown Tata Motors has taken the lead interest in LNG, with the debut of country’s first LNG-powered Tata Marcopolo LNG Bus (LPO 1613) in Kerala late last year. In fact, the company was the first OEM here to come up with gas-run heavy truck Prima 4032.S LNG, displayed at 2014 Auto Expo. Eco-friendliness and soft price make it a compelling alternative fuel for the company. LNG is also cheaper than diesel by nearly 40 per cent and almost 15 per cent dearer than CNG as well.
It is also reported that other domestic CV makers including Ashok Leyland, Mahindra, and BharatBenz are developing LNG variants of their products. Scania, for instance, has already introduced ED95 engine series (Euro 4 compliant) in its products that can run almost completely on bio-fuels including Bio-CNG. In the supply side of the LNG, India’s largest importer of LNG Petronet, and Reliance Petroleum have expressed their interest in offering LNG at fuel stations.
Yet, the LNG dialogues happening in India are solely related to conventional natural gas that are non-renewable and purely imported. There is a need for a much `cleaner´ approach to auto LNG, by encouraging local and commercial production of Bio-methane. Both the government and the auto industry has to work together in this regard, so as to extract the real `eco´ benefits of using LNG on CVs.
LNG-powered Volvo FM and FH range of trucks introduced in Europe.
Amid all electrification debates in the transportation sector, global CV makers are stepping-up their ‘gas’ pedals to mitigate climate impacts of the trucking industry! They are betting high on Liquefied Natural Gas (LNG) or Biogas (renewable natural gas) as a pragmatic alternative to conventional diesel for heavy regional and long-haul trucking operations, especially in Europe. The proponents claim that LNG offers considerable environmental and public health benefits with 20 percent lower CO2 emissions than diesel, even up to 100 percent emission cut by using Bio-LNG, thereby realizing sustainable, eco-friendly haulage. It also promises reduced nitrogen oxide (NOx) emissions, with virtually no particulate emissions, while LNG-powered engines are said to be significantly quieter than conventional diesels.
Volvo Trucks, for instance, has recently unveiled the first-ever gas powered truck in the European market. The company is now working together with gas suppliers and customers to expand LNG infrastructure in Europe. “With EU making more stringent regulation on CO2 figures for heavy vehicles, we see a clear possibility for increasing LNG market shares as a vital part of the solution to lower emissions” notes Lars Mårtensson, Director of Environment and Innovation at Volvo Trucks.
Volkswagen Group Logistics, together with Scania, is also in favor of promoting LNG as a truck fuel. It has revealed that more than 100 LNG trucks are to be used on the roads of north Germany in future as a commitment towards sustainable logistics. It is in dialogue with gas suppliers to construct LNG refueling stations in the region. Scania claims that its LNG powertrain, apart from 20-90 percent less CO2 than diesel engines depending on the choice of fuel, emit some 95 percent less NOx. Particulate emissions during combustion are virtually completely avoided by up to 95 percent, while the noise levels are curbed by about 50 percent (-3 db), according to the truck maker.
Italy-based IVECO, one of the pioneer of natural gas transportation in the industry, has also introduced Stralis NP (Natural Power) 460 hp truck for long-haul operations. The brand claims up to 95 percent cut in CO2 emissions by using compressed or liquefied biomethane as fuel. The company already supports a running parc of 22,000 natural gas vehicles across Europe.
Conventional Natural Gas is fossil fuel-derived, predominantly made up of methane (CH4). Alternatively, Renewable Natural Gas (RNG), a.k.a Bio-methane or Biogas, can be produced from renewable means like decaying organic materials or bio-waste. But, to be used as a transportation fuel, the natural gas has to be either compressed (CNG) or liquefied (LNG). Notably, the primary source of natural gas determines its `cleaner´ credentials. Both the alternative fuels (CNG and LNG) can be locally produced, even costs less than diesel in many European countries and in India as well. Although CNG is widely used for passenger cars and buses, LNG meets the longer range requirements of trucks, as liquid is denser than gas (CNG) and, so, more energy can be stored by volume in a given tank. Further, the carrying capacity of vehicles powered by the LNG is 2.5 times more than that of CNG.
Energy experts opine that long-term availability and commercial viability of natural gas is excellent in a global level. Biogas, for instance, thus far has been only produced in limited quantities across the globe. With more and more gas-run products coming up, the locally production of the alternative fuel can be amplified in every market. “All told, this makes liquefied gas the best widely available climate alternative on the market for long and heavy transports. What is needed now is gas-powered trucks that can compete with diesel in terms of performance and fuel consumption, and continued expansion of LNG infrastructure. In both cases major progress has been achieved,” observes Mårtensson of Volvo Trucks.
*An edited version of this article has been published in the January 2018 edition of MotorIndia Magazine.
Why can’t we engineer a low-cost electric bus platform using Lead Acid batteries, along with charging and mechanized swapping infrastructure tailor-made for specific local needs?
Electric buses are the serious talk of the ‘auto’ town these days, so it may appear as if the era of silent, zero-emission urban transport is finally here. But is it? Any such claims actually amounts to stretching the truth somewhat, perhaps, by over a century! The history of electric buses is as old as the history of buses itself, that the application of electric propulsion and battery technologies in buses precedes that of diesel or even IC engine. For instance, the city of London reports demonstration of electric buses as early as 1893, while the London Electrobus Company introduced the battery-electric double-deckers in 1907. Infrastructure for recharging and swapping of depleted batteries were set up too – a century ago!
Then how did the electro-mobility disappear from the automotive scene you may wonder. Failure of technology? Practicality or affordability issues? Not really, the interest in battery buses waned in the light of improved reliability of motor buses and other urban transports. Historians of technology opine that the booming oil industry and war economy oriented industry’s focus towards internal combustion engines. Further, for a technology to succeed, it has to be commercially bankable for businesses in a capitalist world, its sustainability or humanistic potentials always take a back seat. The IC technology, with the business potentiality of bombastic components industry and ever paying oil base, must have definitely won the case against the impeccant battery-electric technology.
Think about it, what if the industry and governments at the beginning of the last century were smart and humane enough to consider some big-picture thinking on the sustainability of mobility systems? Things would have been very different by now – electro-mobility must have become the norm of the industry; battery-electric technologies may have attained greater heights of efficiency; clean energy may have got greater push, etc. – you can add all those future mobility visions that we are mulling over a century later now. We are reaping all those falls that our previous generation of industry and society sowed long back. We are right at the start point, rethinking the entire construct of urban mobility, once again! It´s a missed opportunity, I would say.
Okay, even if we take pride in the way the battery-electric technologies (especially Lithium-ion) have improved in our times, how efficacious are they in producing the intended results? Keep aside the range anxiety associated with them, are they affordable in the first place? That too for a developing society like ours, where we still fight several battles on various social indicators that the Western world has already won, how can we expect ourselves to adopt EVs in the same pace as they can? Nor our energy infrastructure is cleaner enough to make a difference.
Having said that, we must try to be the part of solutions to our limitations as well. Discovering local and affordable electro-mobility solutions is crucial for our society to ward-off the ills of present-day urban mobility and embrace EVs. In this regard, we met Mr. H.K. Agarwal of Sympar Associates, Delhi who is currently assisting the development of technology at technical institutes for mass conversion of pre-owned cars and buses to battery-electric vehicles (BEVs). With over 65 years of academic and technical experience in the fields of electric traction and electronics, he has a very different take on the scenario of electro-mobility in India, battery-operated buses in particular.
Local and Affordable Solutions
Notably, Mr. Agarwal was involved in a BEV project led by Late Prof. (Emeritus) R. Arockiasamy of IIT-Delhi some 15 years ago. It involved conversion of a standard Tata chassis bus into a hybrid battery vehicle featuring a battery bank with a tiny diesel generator. The project let to an operational working model successfully tried within the IIT Delhi campus. “It was an indigenous, cost effective and short gestation solution for intra-city needs, but we were well-ahead of times that the project was left in limbo” he says. The electric propulsion system of the project used DC Traction motor from Crompton and the controller was designed by Prof. Arockiasamy´s team. The battery pack consisted of 20 Lead-Acid (LA) batteries, recharged by a small generator.
Taking stock of new technological developments, Mr. Agarwal admits that the DC Traction motors are no longer used in EVs, and the AC Traction Permanent magnet (brushless) motors are best suited for e-buses. By why give up LA Batteries for the expensive and much-hyped Lithium-Ion (Li-ion) batteries, when its claimed benefits and reliability are often disputed, he asks. Although LA batteries have relatively low energy-to-weight ratio, they are highly reliable and proven, locally available at affordable costs, easily replaceable, and recyclable. On the contrary, the Li-ion batteries are thrice more expensive and imported, pushing up the cost of the entire EV, while the recyclability know-how is still immature even in developed markets, he adds.
But doesn’t weight and compactness of battery pack matter in electric buses? Let´s consider the conundrum this way. We are taking about intra-city bus applications having pre-defined routes and trips, with speeds not more than 50 kmph, along with limited passenger payload. Thus, the veteran says, the battery pack can be tailor-made to suit local route requirements by either increasing or decreasing the battery units. Even if the extra weight of LA batteries result in limited travel range, this can be managed by trip and charging time management, he affirms.
Moreover, won’t LA batteries in e-bus applications face challenges in power delivery and charge/ discharge cycles? City buses involve frequent stop and sudden acceleration, for which the battery architecture should be robust enough to supply ample energy for disposal. Mr. Agarwal replies that sound battery management is essential for any EV, may it be Li-ion or LA batteries. There is a heavy drain of energy while starting from idle, climbing up a steep, or during sudden acceleration, whereas while braking or moving down the hill, the energy released can be recuperated. Therefore, he suggests engaging super capacitors as short-term energy repository in the architecture, from which power can be discharged for starting or acceleration needs, and can be replenished out of regenerative braking. This can eliminate the short-term energy demands of an e-bus.
For longer range and quicker charging cycles, he proposes low power gensets of 10-15 kW rating to supplement the battery architecture. They can run on relatively cleaner fuels like LPG, CNG, Biogas, or Biodiesel only on demand with start / stop feature, and maintain constant rpm. Air-conditioning needs can also be taken care, while the size of the battery and its load weight can be reduced as well. An another alternative is replaceable battery pack, where a charging and mechanized swapping infrastructure can be set up at each terminals to avert the charging periods during peak hours. He adds that the fast charging technologies popular in the West may prove fatal in the tropical weather of our country, may even damage the batteries.
In fact, the concept of swappable batteries has caught the attention of Indian government in place of conventional charging infrastructure as in the developed markets. It is learnt that EV policies may favour such cost-effective battery ecosystem, as the government is aiming towards bringing 10,000 electric buses on road in the years to come. Further, private investments in this regard is also expected to pick up, with firms like SUN Mobility, Exide Batteries, Amara Raja Batteries, and Electrotherm reported as working on swappable batteries.
“We have to think local to find answers to our own problems” says Mr. H.K. Agarwal, adding that cost effective battery/ hybrid-electric powertrains for buses can be locally devised to address our immediate needs. Apart from building e-buses on new chassis, it is very much economically feasible to convert standard diesel buses into BEVs, he claims. For instance, there are over 1.6 million buses running on Indian roads, a huge chunk of those are city buses. With new scrappage regulations like that of NGT on culling vehicles over 10 years in Delhi NCR, they can be easily converted into eco-friendly vehicles. That way, tax payers’ money can be saved, he claims. Mr. Agarwal is approaching various technical institutes, auto components makers, and EV entrepreneurs across the country in search of partners to bring out an operation model of low-cost electric buses for commercial viability.
Although the National Electric Mobility Mission Plan 2020 aims to usher in 7 million EVs on Indian roads by 2020, there exists a huge void in actual number so far since its launch in 2013. The only successful display of EVs on our roads are the e- rickshaws, which again is a local and cost-effective solution. I think it’s time to jump into action with affordable technologies and local ideas, rather than wait forever for a one-stop solution to e-mobility. There isn’t any yet!
The hybrid system offers up to 8.5 percent lower fuel consumption than the conventional diesel-powered Citaro.
Daimler Buses had world debuted its Citaro Hybrid range of urban buses under the Mercedes-Benz marque at the 2017 Busworld Europe, Kortrijk in Belgium. The company has now made the hybrid technology optional for a wide range of Citaro buses fitted with both diesel and natural gas-powered engines (NGT models) in rigid, articulated, or low-entry layouts. Daimler says that it considers hybrids not as an interim technology en-route to electric drive systems, but as an efficient way to hone the ICE systems.
The Citaro hybrid combines a series of energy-efficient technologies to save fuel consumption. To start with, the Intelligent Eco Steering, an electro-hydraulic steering system, operates only on demand unlike the conventional hydraulic steering systems. Next is the braking energy recuperation, by which the electric motor that assists the IC engine acts as a generator during braking and overrun phases.
The energy thus generated is then stored in double layer capacitors called as `supercaps´ (aka supercapacitors) that are characterized by high power density. They are best suited for high power peaks and quick changeover between charging and discharging during start/stop cycles in typical city bus operation. Daimler has ideally placed the twin-modules supercapacitors (2 Ah total capacity) containing 16 double layer capacitors at a space-saving location over the roof. A water-cooler inverter converts the DC into AC to drive the electric motor.
The disc-shaped synchronous electric motor, on the other hand, is positioned between the IC engine and the automatic gearbox, just like the way it was done in Mercedes-Benz E-300 BlueTEC Hybrid some five years ago! In fact, this motor is used in Mercedes S-Class cars as starter motors! This straightforward design is perhaps compact and less-heavy, also effective in assisting the engine when it demands power, especially while moving off from idle. The electric motor simply reduces the engine burden, that is why there is hardly any boost to the max power and speed generated. Yet, fuel consumption is reduced in the process.
Again like its passenger cars, Daimler has equipped the Citaro hybrid with a 48 volt energy architecture thereby eliminating any high-voltage safety restrictions in its design. The compactness of the hybrid system results in almost no loss of passenger space in the cabin. The hybrid system is compatible with Citaro´s two prime range of engines – Mercedes-Benz OM 936 G 6-cylinder in-line diesel in both vertical and horizontal layouts, and M 936 G natural gas engine used in Citaro NGT.