The lubricant will affect the energy consumption in both ICE and BEV as they have a strong effect on powertrain friction.
Even though the overall carbon foot print of the trucks were not assessed it can be concluded that the contribution from the power train lubricants to the overall carbon footprint of the ICE truck is relatively small, and has the potential to be reduced further by a factor ~10 for BEV and FCEV trucks.
Table 1: Power train lubricant need of a typical Internal combustion engine (ICE) truck.
Table 2: Power train lubricant need of a BEV or FCEV truck propelled by a single drive eAxle.
During its life, the ICE truck will consume more than half a million litres of diesel fuel emitting 1400 tons of CO2
It is clear that a substantial part of the carbon footprint is related to the usage phase of the vehicle. This means that the power train efficiency, both for ICE, BEV and FCEV, has a large effect on the carbon footprint and even the smallest improvement has a larger potential than reducing the carbon footprint of the lubricant itself. This is important as the lubricants used will affect powertrain friction.
, making the contribution of the lubricant 0.15% to that of the fuel. Or in other words if the carbon footprint of the lubricant would be zero this corresponds to a reduction of fuel consumption of the vehicle from 2.5 to 2.49625/10km.
Correspondingly the BEV will consume ~2.5 GWh kWh electricity corresponding to 580 ton CO2
e during
life, if produced according to EU Mix 2020 [2]. The carbon footprint of the lubricant is 0.03 % of that of the energy consumption.
European level – Greenhouse gas emission intensity of electricity generation by country
It is important to understand that even with BEV and FCEV we still must try to further reduce the carbon footprint of the lubricants and we must do it without decreasing the energy efficiency of the power train. Or even better reduce the carbon foot print of the lubricants while reducing the power train losses also preventing wear.
There are various alternatives available to reduce the carbon footprint of a lubricant, often connected to the base oils used. Base oils like synthetic esters, Group III and Polyalphaolefin (PAO) base oils manufactured from renewable feedstock are emerging on the market. These can be used to replace the corresponding petrochemical base oils in high quality lubricants. Other ways are to replace crude oil based Group I and Group II base oils with re-refined base oils which often are good quality falling into API Group II classification. Proper disposal of the lubricant after use will reduce the carbon footprint further especially if the lubricant can be reused, repurposed or re-refined to be used in new lubricants.
Figure 2: Average greenhouse gas emissions in European electricity grid [2]. N.B. that as the life expectancy of the trucks are 15 years, the carbon footprints of the BEV and FCEV trucks will decline as the electricity in the grid will continue to improve. There is also a huge variation between the European countries.
In a Fuel Cell Electric Vehicle (FCEV) suited for European long haulage operation an eAxle of the same type as in the BEV will be used. And thus the need for power train lubricants are identical to that of the BEV. Due to losses in converting energy from electricity to hydrogen and back to electricity the energy consumption of the FCEV is higher than that of the BEV making it more sensitive to how the energy is produced.
References: [1] Sustainability: What does it mean for base oils and finished lubricants? Kettunen. M. Presented at ICIS 23rd Base oil & Lubricants Conference.
[2] Greenhouse gas emission intensity of electricity generation by country. Report published by European Environment agency
LINK
https://www.scania.com
LUBE MAGAZINE NO.170 AUGUST 2022
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