Photography by Anthony Dawton
We began with a hydrogen fuel cell, a manifesto for sustainable design and a blank sheet of paper. Every aspect of the Rasa has been created and interrogated for simplicity, efficiency, lightness, strength, affordability, safety and sustainability. And the name Rasa is a nod to that blank sheet of paper – Tabula Rasa means ‘Clean slate’ in Latin.
This first car is a two seater ‘network electric’ car, powered by a hydrogen fuel cell. The engineering prototype has clocked over 60mph and has been weaving neatly through the traffic in London, as well as gliding down the country lanes of Powys.
The chassis is a carbon fibre monocoque made from very lightweight but extremely stiff carbon fibre composites. The monocoque chassis weighs less than 40kg.
Our car is very light – the engineering prototype weighs 580 kg. It embodies various key features:
It’s the synthesis of all these technologies that delivers the groundbreaking efficiency and range, many times better than inserting fuel cells into conventional, heavy, vehicles. The production prototype should do c.250 mpg (equivalent), with a range of 300 miles. Emissions are zero at tailpipe and c.40gCO2/km Well-to-Wheel – even if the hydrogen comes from natural gas.
For more detail on our choice of hydrogen over batteries, click here.
The hydrogen passes through a Proton Exchange Membrane in the fuel cell where it combines with oxygen to form water and electricity. The electricity then flows to the motors in each wheel. These motors are small, lightweight and give the car 4 wheel drive.
When the car brakes, the kinetic energy, that is normally lost in the form of heat, is captured as electricity. As the car slows, this electricity floods into a bank of super-capacitors at the front of the car. Unlike a battery, these super-capacitors can take a huge charge very quickly, but they don’t store a lot of energy. The energy they take in is sent back to the motors again and provides the energy to accelerate.
Our innovative network design means that we only require a fuel cell big enough to provide cruising speed power, rather than acceleration. We are getting more than 50% of the braking energy back, which is used to boost acceleration. It is the culmination of 15 years of development and it’s driving beautifully.