ALTERNATIVE FUELS AND SUSTAINABLE VEHICLE TECHNOLOGIES
This article is an excerpt from the Sweco Urban Insight report “E-magine a journey through Europe – Energy infrastructure for sustainable mobility.” It defines the characteristics of the three most prevalent alternative fuel technologies: electricity-, hydrogen- and biofuel-powered vehicles. It also describes the different types of chargers available for electric vehicles – the most common type of alternative-fuelled transport. As such, it serves as a useful introduction to these topics.
This report focuses on electric vehicles and their integration into society in coming years. It presents a case study that was conducted to examine the viability of long-distance travel using an electric vehicle today. The report also looks into the future and considers the demand and requirements for modern energy infrastructure that can meet expectations and technical demands for the development of sustainable mobility.
Electric vehicle (EV) technology is available in various forms.
- Firstly, the Battery Electric Vehicle (BEV) is powered solely by an electric motor using electricity that is stored in an on-board battery. This battery must be regularly charged with electricity from the grid or, for EV owners, with on-site renewables (e.g. from solar PV). The driving range are growing with battery technology development.
- Hybrid Electric Vehicles (HEVs) combine a conventional combustion engine with an electric motor system. The HEV battery utilised in this type of vehicle is rather small and cannot be charged from the grid. Instead, the battery is charged from regenerative braking, in which an energy recovery mechanism converts kinetic energy into a form that can be used immediately or stored until needed.
- Plug-in Hybrid Electric Vehicles (PHEVs), on the other hand, use the electric motor as a main engine, with the combustion engine used only when the battery is low or when higher operating power is required. As the name indicates, the larger battery can be charged from the electricity grid.
- The third hybrid type, the Range-Extended Electric Vehicle (REEV) is powered solely by an electric motor supplied with electricity from the battery. This battery is charged from the grid, but also from a small combustion engine acting as a generator, which only activates when the vehicle exceeds its battery-only driving range.
Fuel Cell Electric Vehicles (FCEVs) are also fully powered by an electric motor. However, compressed hydrogen gas is used as fuel to generate the electric power via a fuel cell. The fuel cell is an electro-chemical cell that converts the chemical energy from the reaction of hydrogen and oxygen into electricity.
First-generation biofuels such as biodiesel and biogas are derived from food crops and have come under fire for threatening biodiversity and contribution to deforestation. Second-generation biofuels, also known as “advanced biofuels”, are derived from feed stock, waste, sewer and recycled vegetable oil and do not cause the same level of harm to the environment. The driving range is the same as for conventional fossil fuels.
Another interesting technology for heavy vehicles, as well as for cars, is electric roads – a vehicle receives electrical power from power lines running above the road or placed within the body of the road. The world’s first electric road opened in Sweden in 2016 and is a two-kilometre strip where electrified lorries use conductive technology developed. The system permits lorries to operate as electric vehicles when on the electrified road and as regular hybrid vehicles at other times.
EV CHARGING OPTIONS
Hydrogen and biofuel-powered vehicles can be refuelled in a similar timescale as petrol or diesel vehicles. However, EVs currently take from between 30 minutes to 12 hours to charge, depending on the charger and the battery capacity. Battery and charging technologies are advancing rapidly, so it is expected that within a decade it will be possible to recharge a large-battery EV within 10 minutes.
- Rapid chargers (private only): Rapid chargers are high-power AC or DC chargers outputting 43 kW AC, and 50 kW or 120 kW DC directly into the EV battery. They utilise a tethered cable, specially designed for safely delivering the power to the vehicle and to provide two-way communication between the charger and vehicle. Chargers usually have three types of cable and connector to allow the various car makes to charge according to their rapid charging socket.
This type of charger is primarily used when on longer journeys, where rapid charging is a necessity. Due to the cost of installing this type of charger and the amount of power it can deliver in a short time, it is often common to pay a premium price to charge, sometimes on par with petrol price equivalent. Rapid charging parking spaces must only be used during charging, e.g. 30 minutes to 1 hour.
- Fast charging stations (public, workplace and domestic): Fast charging stations allow EV drivers to connect 7 – 22 kW power to the EV’s on-board charger. These stations are sometimes used for destination charging, allowing drivers to stay for as long as they need to utilise the parking space. The EV must be moved when the time expires.
Some of these charging points have signs specifying a parking/charging time limit, e.g. 4 hours. Drivers therefore cannot rely on there being a space for charging, even in instances where a car occupying a charging space has finished charging. In these cases, green/red signs would be useful, as queuing drivers would be able to see when the occupier of the space might be returning, or could contact them to find out their expected return time.
- Slow charging stations (public, workplace and domestic): Slow charging points allow EV drivers to connect to a socket or dedicated station that delivers up to 3 kW (10 A). These are usually classed as destination charging stations, mainly because they take up to 12 hours to charge. As with public fast charging stations, drivers searching for a public slow charging station should not rely on there being a space for charging, even if the car occupying the space has finished charging.
Today the type of charging options and business models differs between countries. This can be an obstacle for the user. This is a working progress, as all new technologies and changing consumer behaviour it takes time. It is an ongoing work with standardisation in order to make it easy to live in Europe with your Electrical vehicle.