Illustration with a French study by Sphera
As illustrated in the last Spark article “11 Trends Toward the Electric Mobility Future,” new regulations tilt the scales in favor of electric vehicles, including hydrogen vehicles. Hydrogen has the unique advantage of emitting only water as exhaust. But what is it really like? Are hydrogen vehicles really cleaner vehicles? Life Cycle Assessment (LCA) is the tool to evaluate the benefits and impacts of this emerging mobility technology, allowing you to compare it to alternatives. A comparative LCA analysis of battery–electric or hydrogen-electric vehicles vs. internal combustion engines (ICE) vehicles allows you to understand the impact with vehicles that provide the same service, which is not always the case in terms of range and distance travelled per fuel charged. The hydrogen vehicle has a range that is close to that of a diesel vehicle, unlike electric vehicles, which often have a much shorter range. So, this blog, comparing hydrogen-electric vehicles, battery-electric vehicles and standard combustion vehicles, is designed to give you a more realistic comparison.
ADEME, the French Agency for Ecological Transition in France, conducted a study as early as 2018, completing it by the end of 2020. France, like other European countries, is adopting a strategy for the deployment of hydrogen-electric vehicles, particularly for mobility applications. This joint study highlights the environmental aspects of the development for the mobility sector.
The purpose of the study, carried out by Gingko 21 and Sphera, which carried out the LCA modelling and calculated environmental impacts with the help of Sphera’s Life Cycle Assessment Software, was to integrate industrial partners. Indeed, many industrial companies that are in the process of integrating the hydrogen value chain in France were on the Technical Committee for this study, including Air Liquide, ENGIE, EDF, AREVA, McPhy, Michelin, Plastic Omnium, Renault and PSA, providing and validating the data to build an LCA study that reflected real industry conditions.
What does the study tell us?
First, we’ve learned that we need to produce and distribute a steady supply of hydrogen in the right way before it is introduced into a vehicle’s tank. Different scenarios were studied to characterize hydrogen fuel and its associated impacts, using key parameters in the upstream chain. Different hydrogen production processes and logistics schemes have been considered: the classical steam methane reforming (SMR) of natural gas, electrolysis of water with variable hypotheses for the electricity mix (France FR 2023 (The FR 2023 mix represents the average electricity mix used over the 10-year period of the study (2018-2028) during which hydrogen production is operated and supplies vehicles, modeled on the prospective data of the Ministry of Ecological and Solidarity Transition.), 100% renewable or European mix), onsite and offsite production including transport to the service station, etc.
Hydrogen production and distribution has a highly variable global warming impact, ranging from 1.9 to 17.5 kg CO2 eq/kg H2 available at the station.
For all the scenarios studied and representative of the conditions within France, the impact on climate change appears to be highly variable. The greenhouse gases (GHG) content of one kg of hydrogen ranges from 1.9 to 17.5 kg CO2 eq.: 1.9 kg CO2 eq. when hydrogen is produced by electrolysis and directly at the service station, 17.5 kg CO2 eq. when it is produced by SMR and distributed to the service station.
But electrolysis is also associated with the worst-case scenario, when the electricity used is itself carbon intensive, meaning when the electricity is produced from coal, lignite and natural gas. Thus, assuming electricity from the average European grid mix, the climate change impact amounts to 23.4 kg CO2 eq/kg H2, or 12 times more emissions than the most favorable scenario in France.
The type of energy carrier (electricity or gas) that feeds the hydrogen production process remains the main contributor to the climate change impact. The optional stage of truck transportation of hydrogen, between the offsite hydrogen production and the service station, has impacts that may be significant if it extends over several hundred kilometers. Indeed, the climate change impact of diesel-powered trucks currently used to transport gaseous hydrogen depends on the distance of transportation, but also on the hydrogen storage operating pressure. This impact is estimated at between 0.35 and 1.12 kg of CO2 eq / kg of H2 transported over 100 km (at 500 bar and 200 bar respectively (Currently, this is the most frequently encountered transport pressure for transporting hydrogen gas. Transport at 500 bar is still prospective.)). On-site production at service station and delivery at 700 bar and, at the very least, with reduced transportation distances, limits the contribution of this stage to global warming.
The manufacture of hydrogen-electric vehicles, like battery-electric vehicles, is a critical step.
In order to put the results of this LCA for hydrogen-electric vehicles into perspective, the study proposes a comparison with internal combustion engine (ICE) vehicles as well as with a battery-electric vehicles. A medium commercial vehicle was modelled with a Gross Vehicle Weight Rating (GVWR) of less than 3.5 tonnes, comprising a hybrid fuel cell/battery architecture, with a 40 kW fuel cell and a 20 kWh battery (Hydrogen-powered LCVs running in France are rare, but the French government is counting on 5,000 hydrogen-powered vehicles running by 2023. Renault already has two hydrogen models (Kangoo and Master) in its catalogue and PSA is preparing to market its first models in 2021.). This vehicle was imagined to be used in commercial fleets for the transport of people and goods for a lifespan of 200,000 km, with an intensive use (like delivery services), requiring autonomy and vehicle availability that justify the use of hydrogen.
The manufacture of the hydrogen-electric vehicle and its equipment generates an impact of around 10.3 tonnes CO2 eq, that is an impact of the same order of magnitude as a battery-electric vehicle:
- The vehicle platform (“Rest of vehicle”), which is common to both types of vehicles, is the largest contributor to emissions (61% and 59%).
- The manufacture of the high-pressure hydrogen tank, made of carbon fiber, and the mobilization of the platinum, which makes up the fuel cell, are the other two major posts responsible for GHG emissions for this stage (15% and 7% respectively).
BEV (FR2023): Battery-Electric Vehicle, powered with the French electricity mix FR 2023.
FCEV: Fuel Cell Electric Vehicle, or hydrogen-electric vehicle. Battery powered with the French electricity mix FR 2023, Fuel Cell with a Platinum load of 0.44 g Pt/kW.
The geographical location of equipment manufacturing is also a significant parameter. For example, emissions related to the manufacture of the battery are 33% lower if it is located in France rather than in China, due in particular to the different electricity mixes.
Using the hydrogen in a commercial vehicle: a hydrogen utility vehicle can have a footprint 11% to 75% smaller than a diesel vehicle for the same service.
Over the entire lifecycle of the hydrogen-electric vehicle—including the fuel production phase, the manufacturing of the vehicle and its equipment and its operation through to end-of-life management—the global warming potential of this type of vehicle appears smaller than the diesel vehicle:
- In the case in which hydrogen is produced by SMR and transported at 200 bar, the impact is 38 tonnes CO2 eq, 11% less than the emissions related to the diesel vehicle, which is 42 tonnes CO2 eq within the same scope.
- When hydrogen is produced by electrolysis at the service station, the impact is 13 tonnes CO2 eq with the French electricity mix FR 2023 (average 2018-2028) and 11 tonnes CO2 eq with 100% renewable electricity, 69% and 75% less than the diesel reference.
This graph shows the results for the 3 categories of compared vehicles: Diesel, BEV and FCEV, showing for each staged bars the main life cycle stages of the vehicles. The manufacturing of the vehicles and their end of life is represented; and the avoided impacts related to the management of the end of life of the equipment (recycling) appear in green, in negative values. For diesel vehicles, the diesel supply and the emissions during the use phase are separated. For BEVs, the electric mix FR 2023 is used to recharge the battery. For the FCEV, 6 cases were chosen: 1/Steamreformer: hydrogen produced by steamreforming, with 100% natural gas or 100% biogas; 2/Electrolysis, in which electricity comes from the FR 2023 mix or is 100% renewable, and with hydrogen transported to the service station at 200 bar or produced directly at the station. The electricity supply (mix FR 2023) is for the battery of the hybrid FCEV.
Furthermore, a hydrogen-electric vehicle powered with hydrogen from electrolysis has a 66 to 75% lower impact (FR 2023 mix and 100% renewable mix respectively) than a vehicle powered with hydrogen from natural gas steam reforming.
The battery-powered electric vehicle is better positioned with regard to emissions, but a comparison needs to take the service provided into account to remain comprehensive.
The climate change impact of the battery-electric vehicle is around 9.3 tonnes CO2 eq for its entire life cycle. This vehicle presents the best results, with a potential reduction of 78% compared to the diesel vehicle.
Nevertheless, it should be noted that this balance depends on the size of the battery fitted to the electric vehicle. In the present study, the battery-electric utility vehicle under consideration is equipped with a 60 kWh battery, for a range of approximately 200 km/day, making it possible to take many trips for this type of use. Nevertheless, diesel and hydrogen-electric vehicles have greater mileage autonomy, as well as different functionalities in terms of payload and payload volume and availability as a result of being able to rapidly fill the tank. As the service provided by these vehicles is different, their comparison remains delicate.
Beyond global warming: depletion of abiotic resources (ores, metals) and energy resources—radioactivity.
The results for all impacts reveal that it is important to complement the above analysis with results from other impact categories and not to limit the analysis to only climate change. The study led to the identification of the depletion of resources (abiotic and energetic) and ionising effects as additional predominant impacts.
Thus, the hydrogen-electric vehicle, like the battery-electric vehicle, requires twice as many abiotic resources (ores and minerals) as the interbal combustion engine (ICE) vehicle. The depletion of resources here is mainly linked to the manufacturing of the vehicle, whatever it is. Battery-electric and hydrogen-electric vehicles have similar impacts. Consequently, the end of the vehicle’s life and its recycling appear as major levers for reducing this impact: potentially, it can be reduced by half if the materials are recovered and reused, avoiding the removal of minerals and virgin materials.
The study also shows that a hydrogen-powered vehicle consumes between 299 and 1,129 GJ of non-renewable energy resources (including nuclear energy) over its entire life cycle, including hydrogen production, vehicle manufacture, use over 200,000 km and end of life. When hydrogen is derived from natural gas or produced by electrolysis with electricity from the FR 2023 mix, its balance is therefore more penalizing than that of the diesel thermal vehicle (581 GJ).
Indeed, the consumption of non-renewable energy resources for the provision of 1 kg of hydrogen at the service station varies, from a ratio of 1 to 20, depending on its production scenarios, requiring a quantity of fossil energy ranging from 25 MJ when the hydrogen is produced by electrolysis with 100% renewable electricity, up to 500 MJ when this same electrolysis uses electricity from the FR 2023 mix.
Hydrogen, used as an energy carrier, involves energy transformation stages, from primary resources to final use, here in a light hydrogen-electric vehicle. These stages thus result in energy losses, and the overall balance with regard to the depletion of non-renewable resources depends on the nature of the resources used to produce hydrogen.
What are the lessons for the future of hydrogen for mobility?
In view of the predominant impacts studied, the scenario with hydrogen produced by electrolysis with electricity from a 100% renewable mix emerges as the most favorable scenario. This scenario appears to be all the more favorable as production takes place at the service station, without a transportation stage. It is therefore recommended to support the development of new hydrogen production capacities from renewable electrical resources in areas close to the places where hydrogen is used.
The manufacturing of both electric vehicles and their equipment appears to be a major factor for several impacts, particularly those related to abiotic resources. The following levers for improvement, relating to the ecodesign of these vehicles, should be sought:
- Lighter vehicles: any reduction in vehicle weight will contribute to the reduction of the demand for materials and therefore the impacts associated with the manufacturing stage, but will at the same time help to reduce the vehicle’s energy consumption during operation. For example, the mass of the hydrogen light utility vehicle is indeed 16% higher than that of the equivalent diesel vehicle.
- Reduction in the quantity of platinum used in the composition of the fuel cells for hydrogen-electric vehicles: if the current platinum content is still high—0.44 g/kW taken as a reference—the prospect of a division by 4 by fuel cells manufacturers seems achievable (Communication from Toyota during the study.). This limitation of the quantities of material should also apply to the carbon fibers used for the high-pressure hydrogen tanks. For battery-electric vehicles, the materials used in the battery (lithium, cobalt, etc.) are also a challenge.
- Longer service life: the impacts linked to the manufacture of the vehicles and their equipment are all the more cushioned when they are designed to operate over a long period of time. A vehicle traveling 300,000 km requires one-third less abiotic resources than a vehicle with a service life of 200,000 km.
- The recycling of materials represents a major challenge: the impact on abiotic resources of the hydrogen-electric vehicle can be reduced by up to 50% if it is applied to all the vehicle’s parts and materials. This presupposes that the recovery and recycling channels are operational. It also requires confirmation that recycled platinum can be reused in fuel cells instead of virgin platinum.
Battery-electric mobility or hydrogen-electric mobility?
Both vehicles types have different performances in terms of range and fueling methods. So the service rendered to the user by these vehicles are thus partially different and comparison remains delicate, as mentioned in the introduction. In this study, a similar service was imagined, with uses made comparable, the vehicles being used for commercial purposes and the batteries being able to be recharged each evening.
Having said that, it appears that the results obtained with a commercial vehicle equipped with a 60 kWh battery are equivalent or better positioned than those obtained by the hydrogen-electric vehicle under consideration. This is due to the hydrogen energy conversion chain, which is longer and therefore has higher losses. The impact on energy resources is thus established, when the electricity comes from a 100% renewable mix, at 1.57 MJ/km traveled for a hydrogen-electric vehicle, compared to 0.7 MJ for a battery-electric vehicle.
A complementary analysis would nevertheless be necessary on a system-wide scale, depending on the nature of the electricity used for fueling. In the case of renewable electricity, electricity production is variable over time, and recharging the battery-electric vehicle by this source might possibly require additional stationary storage of the electricity. The question of the temporality of the production, recharging and use of the vehicle thus makes the question of comparing these two types of mobility complex, beyond the simple question of energy efficiency.
