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Publications (52)
Greenhouse gases emissions reduction in the energy and transportation systems is extremely important. Nonroad mobile machines (NRMMs) are a key factor of production in many industrial and transportation systems with high‐energy intensity. NRMM cover a wide range of application sectors and operate often in harsh environments. This study presents a l...
The total cost of ownership (TCO) of trucks is known as one of the main decision-making factors by logistics operators for adopting alternative powertrains such as battery electric trucks (BETs). In this study, we develop a very detailed levelized cost of driving (LCOD) model to analyse the TCO of BETs and conventional trucks (CTs) in medium and he...
Zero-emission trucks for regional and long-haul missions are an option for fossil-free freight. The viability of such powertrains and system solutions was studied conceptually in project ESCALATE for trucks with GVW of 40 tonnes and beyond through various battery electric and fuel cell prime mover combinations. The study covers battery and fuel cel...
Zero-emission trucks for regional and long haul missions are an option for fossil-free freight. The viability of such powertrains and system solutions was studied conceptually in project ESCALATE for trucks with GVW of 40 tonnes and beyond through various prime mover combinations. The study covers battery and fuel cell power sources with different...
Auxiliary diesel heaters are commonly used in all types of vehicles in cold climates and conditions around the world. Electric buses used in public transport utilise diesel-burning auxiliary heaters to provide thermal comfort for passengers under cold weather conditions while maintaining the operational range otherwise reduced by electric heating....
This paper presents a pre-normative roadmap that foresees the developments in the charging of heavy-duty electric vehicles (HD-EVs). It supports and facilitates the future standardization efforts of charging technologies by creating an overview of the popularity of charging technologies and the end users’ needs. The required input for the work was...
Incremental capacity analysis (ICA) is a widely used method for assessing Li-ion battery state of health (SOH). The ICA method is typically applied to low C-rate charging or discharging, which is seldom feasible in online SOH estimation in real applications. In this paper the applicability of the ICA method to higher C-rates is investigated with C/...
Large scale adoption and public acceptance of Electric Vehicles (EVs) require availability of charging stations. Electrification of transport has been identified as the one of the significant factors that would increase the power demand. Management of charger load has become a matter of concern for the power system engineers. Uncoordinated charging...
Ministry of Economic Affairs and Employment of Finland. MEAE Sector Reports 2021:6.
In June 2020, The Ministry of Economic Affairs and Employment of Finland launched work to formulate a national battery strategy that will enable Finland to strengthen its role as a pioneer in sustainable battery manufacturing and recycling. The working group consi...
This paper demonstrates the potential of a developed simulation tool for electric vehicle systems to replicate the real life operational activity of a bus line using techno-economic studies. The system-level concept represents holistic view of the bus operation and charging infrastructure, including different operational conditions such as current...
![Fig. 9. Shares of electricity generation by fuel in 2015 [54].](profile/Ari-Hentunen/publication/337187080/figure/fig2/AS:824382901477384@1573559608175/Shares-of-electricity-generation-by-fuel-in-2015-54_Q320.jpg)
The use of Li-ion batteries for stationary energy storage in households represents a viable solution to mitigate climate change when compared with the reference situation of electricity supply from the grid in various countries. This study quantifies the climate change impacts of production, use, and disposal of NMC batteries and compares the impac...
Optimization and proper planning of electric vehicle systems becomes even more important as the number of electric vehicles grow, and the vehicles interact when sharing the same charging infrastructure. Different aspects related both to the vehicles themselves and the charging has to be considered in order to achieve a system that is economically c...
A fleet of electric buses can be a challenging load for power grids. This opens interesting opportunities for dialogue between power system design and electric bus route and concept development. A suite of cooperating tools was created to study this interaction, combining a power-grid-connection cost model, a route design and drawing tool, and a to...
During the life of a Li-Ion battery, capacity and power capability fade. Despite this degradation, an electric vehicle battery needs to deliver designed power performance until battery end-of-life. Comprehension of battery performance degradation is required to design sufficient margin for power capability and thermal management. This paper propose...
VTT has together with several partners created a multi-dimensional demonstration environment for electric busses and their supporting infrastructure. The on-going demonstration in the city of Espoo – part of the Helsinki Metropolitan area - is unique in many aspects. One of them is the weather: due to the local climate conditions, the ambient tempe...
Electric bus energy consumption is mainly due to the vehicle traction. Additionally, auxiliary systems such as cabin heating-cooling, air compressor, and power steering consume energy. One way to optimize the consumption is a Driver's Aid System (DAS). Based on the route information, DAS provides the driver the optimal driving suggestions, and simu...
Key challenges in traffic systems are carbon footprint of the vehicles, local emissions, noise and congestion. Fully electric city buses offer a solution to these challenges in public inner city transport. At the same time, electric buses open up for a lower total cost of ownership (TCO) provided that the vehicle, charging infrastructure and new op...
Protective coatings based on manganese cobalt oxide spinels are required in solid oxide fuel cells (SOFCs) to prevent the evaporation of volatile Cr(VI)-compounds from the metallic interconnectors and to minimize high temperature corrosion. Atmospheric plasma spraying (APS) was used to manufacture dense manganese cobalt oxide protective coatings on...
Interconnects employed in solid oxide fuel cells require electrically conductive protective coatings such as those based on manganese cobalt oxide spinels in order to prevent evaporation of volatile Cr(VI)-compounds and to minimize high temperature corrosion. MnCo2-xFexO4 based (where x = 0.1 and 0.3) oxide spinel protective coatings were manufactu...
Heavy-duty commercial vehicles such as mining vehicles, cargo handling machines, and buses have much in common with passenger cars. They are equally affected by tightening emission regulations and high cost of fuel, challenges that increase the attractiveness of electrification of these vehicles. Commercial vehicles have also special attributes whi...
Battery is a critical component of an electric vehicle and electric non-road mobile machinery. The performance of a battery system must be assessed by experimental testing to achieve high reliability. This paper describes the development and validation of a battery pack for a mining load-haul-dump loader application. The typical duty cycle is used...
Contact resistances between Crofer 22 APU and Crofer 22 H interconnect plates, Ni mesh and Ni-8YSZ anode interfaces were measured under an anode gas atmosphere (97%H-2 + 3%H2O) at 700 degrees C and 800 degrees C and current densities of 0 and 0.7 A/cm(2) for durations up to 3000 hours using the 4-point DC conductivity technique. Phase transformatio...
Protective coatings are needed for metallic interconnects used in solid oxide fuel cell (SOFC) stacks to prevent excessive high-temperature oxidation and evaporation of chromium species. These phenomena affect the lifetime of the stacks by increasing the area-specific resistance (ASR) and poisoning of the cathode. Protective MnCo2O4 and MnCo1.8Fe0....
Short-term changes in the electrical conductivity of different Ni–YSZ composites (cermets) were measured by an in-situ 4-point DC technique. The isothermal reduction was carried out in dry, humidified or wet hydrogen at temperatures from 600 to 850 °C. The cermets reduced at 600 °C showed a stable conductivity of about 1100 S/cm, which increased to...
During operation solid oxide fuel cells are stressed by temperature gradients and various internal and external mechanical loads, which must be withstood. This work deals with the optimization of the strength of as-sintered anode supported half-cells by imposing changes to production parameters, such as powder milling and sintering temperature. The...
Chromium poisoning is a well-identified performance degradation process in solid oxide fuel cells (SOFC). While stainless steel interconnects have been identified to be a significant source of chromium, the contribution of the chromium from balance-of-plant (BoP) components located upstream of the cathode still needs to be ascertained. The aim of t...
Nickel oxide and yttria doped zirconia composite strength is crucial for anode-supported solid oxide fuel cells, especially during transient operation, but also for the initial stacking process, where cell curvature after sintering can cause problems. This work first compares tensile and ball-on-ring strength measurements of as-sintered anodes supp...
The short-term changes in the electrical conductivity of Ni-YSZ composites (cermets) suitable for use in Solid Oxide Fuel Cells (SOFC) were measured by an in-situ 4-point DC technique. The isothermal reduction was carried out in dry, humidified or wet hydrogen at temperatures from 600 to 1000 C. While the cermets reduced at 600 degrees C showed a s...
Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high operation temperatures in such oxidising conditions where chromium compounds evaporate and poison the cathode active area, causing the degradation of the solid oxide fuel cell. In or...
One of the main drawbacks of anode-supported solid oxide fuel cell technology is the limited capability to withstand reduction and oxidation (“RedOx”) of the Ni phase. This study compares the effect of RedOx cycles on curvature and strength of half-cells, composed of a Ni-YSZ support, a Ni- YSZ anode and an 8YSZ electrolyte. Five different treatmen...
Journal of Power Sources Vol.195 Nr.9, 2677-2690 Repeated reduction-oxidation (redox) cycles on Ni-based solid oxide fuel cells (SOFC) have been experimentally well investigated and are known to be detrimental to the thermomechanical stability of the composites, especially on anode supported structures. In the present work the mechanistic analysis...
![Figure 1. The principle of operation of a solid oxide fuel cell. [10]](profile/Mikko-Pihlatie/publication/45834949/figure/fig17/AS:668900886863880@1536489807383/The-principle-of-operation-of-a-solid-oxide-fuel-cell-10_Q320.jpg)
VTT PublicationsVTT Publications 740 An operating Ni-based SOFC can be severely damaged by inadvertent oxidation of the nickel. A central way to improve this Achilles' heel is to design and prepare a dimensionally stable anode half cell that does not overload the electrolyte upon re-oxidation. Understanding the mechanisms that lead to the redox exp...
Despite active development, solid oxide fuel cells (SOFCs) based on Ni-YSZ anodes still suffer from thermomechanical instability under conditions where the anode side is exposed to oxidising conditions at high temperature. In the first part of the paper, structures and solutions, which could improve the redox stability of Ni-YSZ anode supported SOF...
A re-oxidation of a Ni-based SOFC can seriously damage the cells. Important aspects of this thermomechanical instability are reduction–oxidation kinetics and the dimensional behaviour of the Ni–YSZ composites. These were investigated in the temperature range of 600–1000 °C and different combinations of reduction and oxidation temperatures. Automate...
The Impulse Excitation Technique (IET) was used to determine the elastic modulus and specific damping of different Ni/NiO–YSZ composites suitable for use in solid oxide fuel cells (SOFC). The porosity of the as-sintered samples varied from 9 to 38% and that of the reduced ones from 31 to 52%. For all samples a linear relation between Young's modulu...
The dimensional behavior of Ni-yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600-1000 degrees C. The effect Of humidity oil redox stability was investigated at intermediate and low temperatures. We show that both the sintering of nickel depending on temperature of the initial re...
One of the main drawbacks of anode-supported solid oxide fuel cell technology is the limited capability to withstand reduction and oxidation ("RedOx") of the Ni phase. This study compares the effect of RedOx cycles on curvature and strength of half-cells, composed of a Ni-YSZ support, a Ni-YSZ anode and an 8YSZ electrolyte. Five different treatment...
Previous studies on Ni-YSZ anode supported SOFC have shown severe mechanical failures upon re-oxidation of the nickel. Ni- YSZ anode support cermets with technologically relevant microstructures were prepared by ceramic slurry processing, tape casting and sintering. The bulk behaviour of the anode supports under reduction-oxidation cycles was studi...
9th Liège Conference on Materials for Advanced Power Engineering, Liege, 27 - 29 Sept. 2010 Chromia released from steel parts used for interconnect plates by evaporation and condensation can quickly degrade the cell (cathode) performance in solid oxide fuel cell SOFC. Coatings on top of the IC plate can work as a chromium evaporation barrier. The c...
