UK-based Riversimple announces it has raised one million pounds through a crowdfunding campaign to develop Rasa. This is a highly fuel-efficient car powered by hydrogen and four electric motors. The vehicle can accommodate two occupants and luggage. Riversimple claims that the boot of the vehicle is big enough to carry two suitcases and a case of wine.
Riversimple says it wants to make efficient cars more desirable and efficiency profitable. The Rasa can travel about 480 kilometres on 1.5 kilograms of hydrogen. Converted to traditional fuel, this is equivalent to consuming one litre of fuel for every 88 kilometres, according to the company. To make this possible, the vehicle is very light: the entire car weighs only 580 kilograms. To achieve this low weight, the Rasa features, among other things, a lightweight but extremely rigid chassis composed of carbon fibre components. The monocoque chassis weighs just 40 kilograms.
Recovering kinetic energy
The car is equipped with four electric motors, with one placed in each wheel. The motors not only power the vehicle, but also function as brakes. In the process, 50% of the kinetic energy released is recovered so that it can be reused to power the vehicle. In addition, the car is equipped with an 8.5kW hydrogen fuel cell.
The hydrogen passes through a Proton Exchange Membrane (PEM) membrane in the fuel cell, where it is combined with oxygen to form water and electricity. The electricity is then delivered to the four electric motors in the vehicle's wheels. Because these motors are present in each wheel of the vehicle, the Rasa has four-wheel drive.
Energy recovery
Recovering kinetic energy during braking is possible through the use of supercapacitors placed at the front of the vehicle. Riversimple states that compared to batteries, these supercapacitors have the significant advantage of being able to store a relatively large amount of energy in a short period of time. However, supercapacitors offer lower storage capacity than batteries. The energy stored in the supercapacitors is returned to the electric motors and used to accelerate the vehicle.
Riversimple claims that this design allows the use of a relatively small fuel cell, large enough to generate the power needed to drive the vehicle around. However, the fuel cell provides relatively little power to accelerate the vehicle and is therefore supplemented by the kinetic energy recovered during braking.
Low emissions
Because the vehicle uses electric motors and hydrogen, the Rasa has zero emissions at the tailpipe. However, emissions are not only caused by the engine in the vehicle, but also by the production process of the fuel used in the vehicle. The emissions released in this process are also known as Well-to-Wheel emissions. Riversimple states that the Rasa's Well-to-Wheel emissions are around 40gCO2/km, even if hydrogen is extracted from natural gas. This, according to the organisation, gives the vehicle the lowest emissions of any production vehicle worldwide.
Also notable about the Rasa is the fact that Riversimple does not want to sell this vehicle to consumers, but wants to offer it via a service contract. Here, customers enter into a contract with a term of typically one to three years. In addition, customers pay for the costs associated with the consumption of the vehicle based on the number of kilometres driven. They are then given a Rasa at their disposal, including insurance and maintenance.
In production from late 2018
Riversimple claims that this business model helps minimise the impact of passenger transport on the environment. The company aims to keep vehicles on the road for as long as possible and thereby maximise its profits. This is in contrast to traditional car manufacturers, which actually turn more profit if they sell more vehicles. The British company expects to put the Rasa into production by the end of 2018.
More information about the Rasa can be found on Riversimple's website.
By: Wouter Hoeffnagel
Source: Riversimple
