JAN OLIVER ROHRL is CTO and Director at Bosch Ltd.
In the past years, substantial effort had gone into improvement of powertrain efficiency to reduce overall fuel consumption and tail pipe pollutants. However, the automobile sector is still looking for additional powertrain solutions to improve efficiency and reduce pollutants. Electrification of the powertrain is the buzzword these days with recent developments in electrification technology. Electrified powertrain has the positive effect of having no local tailpipe emissions.
Looking at the growth of the automobile sector over the last years, the government and the industry are searching for new ways to reduce CO2. An innovative and immediately deployable approach to reduce CO2 emission could be using our present combustion engines with alternative e-fuels, which are derived from renewable sources and are, at least, CO2-neutral. So, this brings e-fuels into focus and this could potentially turn out to be a disruptive scenario for the transportation sector.
While electrification may be the right technology in the current market scenario for passenger cars and smaller vehicles such as two- and three-wheelers, it may not be the only solution for all classes of vehicles. For example, long haul trucks and other transport sectors such as aviation and ships do not have a readymade electrified solution in the medium term. Freight trucks, aviation and ships contribute to over 50 % of greenhouse gases coming from mobility, (1). These sectors need focus if the world wants to reach the agreed and defined “well below 2 degrees” target, which was also signed by India during the last climate change conference in Paris.
HOW TO CALCULATE CO2: ‘TANK TO WHEEL’ VS ‘WELL TO WHEEL’
Yes, electrification of the powertrain gets rid of local tailpipe emissions. But what about CO2 emissions, which is a global topic? Well, that’s not an easy answer.
There are two views one must take here – one is the ‘tank to wheel’ CO2 view, i.e., the net CO2 emission released during combustion in the engine out of the tailpipe. Here, electrification is perceived to have a huge role to play, as naturally no combustion process exists in an electric vehicle, hence ‘zero’ CO2.
The second view is the ‘well to wheel’, which focuses on how much additional CO2 is needed to produce and transport the fuel/ electricity. Herein, the net CO2 output depends on the energy mix of a certain geography. For example, in regions where electricity is generated from renewable resources such as hydro or solar, and is subsequently used to charge automobiles, the net ‘well to wheel’ CO2 output is minimum. However, in regions that are reliant on coal and other fossil fuels to generate electricity, the net ‘well to wheel’ CO2 emission levels would be much worse than using the fuel directly in the vehicle. This is because there are multiple transitions of this energy as fuel converts to electricity. There is loss in electricity transmission in this manner before it is even used to charge a vehicle.
In this case, it is not just the ‘well to wheel’ view that is important, but also the technology itself. As battery technologies are still growing fast, I would say, we are not yet at inflection. There is a lot of scope yet to improve the efficiency of automotive powertrain batteries. Hence, long haulage trucks for example, do not yet have a series of solutions yet.
ALTERNATIVE SOLUTION FOR THE LONG HAUL SEGMENTS
Looking at recent trends in logistics, freight movements and long-distance commutes are only going to grow further in the years to come. The net CO2 reduction gained from implementing improvement measures in passenger cars and smaller automotive would not offset the cumulative increase in CO2 emissions coming out of the increased usage of long haulage trucks, aviation and ships. Thus, to reach the stipulated climate targets, there is a pressing need to not just electrify small powertrains, but to also look at solutions in the large powertrain segments.
One such ready-to-use but much less explored solution is ‘Engineered Fuels’. E-fuels, also called CO2-neutral synthetic fuels, can be manufactured to meet complex required specifications. The flexibility to effectively engineer the chemistry of fuel enables blended compatibility with either gasoline or diesel engine, or allows fuels to be used in totality. Furthermore, the precise engineering of fuel chemistry enables strict control of emission output released by the combustion of these fuels.
What’s attractive about this option is that current fleets can be applied to run with these fuels, thereby reducing the CO2 impact with immediate effect. As additional benefit, the filling and ‘charging’ infrastructure is already available with existing filling stations. These engineered fuels are called CO2-neutral as CO2 from source, or air, is used to manufacture the fuel and the resultant CO2 emitted from cars is lesser than or equal to what goes into manufacture of the fuel. As a result, we could create a CO2 recycling process.
Sources of E-fuels are aplenty; they can be synthesised from natural gas, crude oil or coal. However, these may not prove to be the optimum sources due to their net CO2 emission output. The synthesis of E-fuel by combining the electricity generated from solar, wind or hydro-energy sources to manufacture hydrogen through electrolysis seems to be the most researched and viable path, (2). Together with the captured CO2 and a synthesis process (e.g., Fischer-Tropsch), E-fuels can be produced on a large scale. Another path that is frequently researched and effectively addresses the emissions problem of existing fleets is the usage of biomass to generate bio E-fuels.
This technology has advanced substantially today and even a few pilot plants have already been set-up to manufacture E-fuels. Bosch is among the handful of organisations and OEMs conducting research on this technology by supporting public funded programmes. In this scenario, a typical plant can trap CO2 from the air and convert it into synthetic e-diesel, e-gasoline, eOME or eDME.
Today, the blending of paraffinic fuel components such as GtL (gas-to-liquid), HVO or future PtL (power-to-liquid) in high percentages (up to 30 %) is already possible without violating EN 590 (diesel fuel) and EN 228 (gasoline) requirements. Complete usage of GtL and HVO has also been established in an increasing number of fleets across Europe. The European Union Standard – ‘EN 15940’ (2016) has set out the parameters and conditions that are necessary for the public use of paraffinic fuels. Properties of paraffinic PtL are very similar to GtL and it is expected to exist within the ‘EN 15940’ specification limits. A few examples of E-fuels are e-Oxymethylene ether (OME3-5), e-Dimethyl ether (eDME), eDiesel and eGasoline (PtL).
The key challenges here are with regards to the cost per unit that is dependent on achieving economies of scale. The cost of E-fuel is primarily dominated by the cost of electricity, which is greater than 70 % of the cost. Besides, large investments are also required to set up these plants. Forecast with a learning curve expect the fuel price without tax at € 1-1.40 on long term, maybe even less.
Considering the technology landscape of today, the use of E-fuels may turn out to be a great alternative to bring down CO2 emissions from existing fleets, long haul fleets, aviation and ships. Further, E-fuels can be used with the existing infrastructure for fossil fuels such as pipelines, bunks, and vehicles. The complete substitution of fleets with E-fuels, or even the partial blending of fuel used in vehicles coupled with the electrification of smaller vehicles, would enable the world to meet the recommended emission guidelines of the Paris climate treaty.
Increase in share of renewable energy generation in energy mix is a crucial factor for E-fuels to be successful. At a study done recently, the price of E-fuel considering synthesis by trapping CO2 from ambient air is around Rs 356 per litre diesel equivalent today, assuming economy of scale. This price is comparable to a country such as India, where roughly 32 % of electricity is generated from renewable energy sources. However, synthesising E-Fuel completely from renewable energy within the country or even importing from a country generating electricity predominantly from renewable energy is approximately Rs 80 per litre diesel equivalent.
E-fuel technology is itself in early stages of demonstration. From an economic point of view, transport sector would play a key role – not just from pressure of CO2 but from pressure of crude imports and sustainability. Policy makers and industry needs an aligned and defined roadmap for market development of E-fuels.
 International Energy Agency