At the moment, electric cars and plug-in hybrids are in an ongoing battle with hydrogen fuel cell cars to become the defacto fuel choice of the future.
For now, thanks to companies like Tesla Motors and Nissan, electric cars have the edge when it comes to market penetration. With falling lithium-ion battery prices, increasing energy density (and thus increased range), a rapidly-expanding public rapid charging network and falling sticker prices, electric cars win over hydrogen fuel cell vehicles when it comes to price, service costs, practicality and refueling availability.
If we’re honest, the only real advantage production hydrogen fuel cell cars like the 2016 Toyota Mirai hydrogen fuel cell sedan and 2016 Hyundai Tucson hydrogen fuel cell SUV have over electric cars is the speed at which they can be refuelled. When you take into consideration the overall inefficiencies of a hydrogen fuel cell vehicle compared to an electric car however, that advantage isn’t enough alone to make hydrogen vehicles a sensible choice for the future.
But what if you could improve the energy efficiency of a hydrogen fuel cell car? What if, instead of travelling 300 miles on five kilograms of hydrogen, it could do the same distance on just 1.5 kilograms? Would that make up for the shortfalls of hydrogen fuel cell technology?
Riversimple, a small automotive engineering company from Llandrindod Wells, Wales, thinks so. And to prove it, the company has just unveiled the Rasa, a road-legal hydrogen fuel cell vehicle that seats two and can travel a claimed 300 miles on 1.5 kilograms of hydrogen. Unlike the 2016 Toyota Mirai hydrogen fuel cell sedan, 2016 Hyundai Tucson FCV and soon-to-launch 2017 Honda Clarity fuel cell sedan however, the Riversimple Rasa isn’t a hydrogen fuel cell vehicle built to appeal to existing automotive trends: it’s built to maximize energy efficiency.
From a distance, there’s a striking similarity to the first-generation Honda Insight which recently joined the Transport Evolved staff car fleet.Small and sleek, the Riversimple Rasa is a two-seat coupe with sweeping roof line that leads to a narrow kammback rear, with the rear wheels enclosed behind aerodynamic rear quarter panels. Then there’s the butterfly doors which hinge upwards and outwards from the vehicle’s roof, making the tiny electric car appear almost double its size when its doors open.
While Riversimple hasn’t given an official coefficient of drag, the sleek design of the Rasa has been constructed to minimize drag as much as possible, ensuring the tiny car uses as little energy as possible to move itself along. Combined with a carbon-fiber composite chassis weighing just 40 kilograms (88 pounds) and similarly light body panels the tiny car tips the scales at 580 kilograms (1279 pounds). That, says Riversimple is about half the weight of a traditionally-built small car. For comparison however, we note that the new 2017 Smart ForTwo two-seat microcar weighs in at about 1984 pounds — which is 705 pounds heavier than the tiny fuel cell coupe.
By contrast, the 2016 Toyota Mirai hydrogen fuel cell sedan, while it can seat four adults, is more than 4,078 pounds.
Aerodynamic design and lightweight construction isn’t the only thing which makes the Resa stand out against other hydrogen fuel cell cars. Instead of a large, hard-to-cool hydrogen fuel cell stack, the tiny car has an equally tiny fuel cell stack rated at 8.5 kilowatts. That’s less than one tenth of the hydrogen fuel cell stack in the Mirai, yet still manages to power the Resa to a top speed of just over 60 mph. We’ll admit that top speed is far too low for serial production, but for now, this vehicle is an exercise in frugality, not speed records. The tiny size means that it’s also far easier to cool the fuel cell stack than other hydrogen fuel cell cars we’ve seen, minimizing the amount of cooling system components needed to keep it happy.
Converting that power to motion is a quartet of in-wheel electric motors which drive thin, low-rolling resistance tires. While the hydrogen fuel cell tank and fuel cell stack live behind the passenger compartment in the rear of the vehicle, the underhood area houses a small bank of supercapacitors specifically designed to help recapture energy during regenerative braking and then feed that power back to the wheels during heavy acceleration.
Riversimple says the Resa manages a fuel economy of around 250 mpge according to its own calculations, and emits 40 grams of CO² per kilometer driven using a well-to-wheel life cycle analysis assuming the is powered from hydrogen reformed from compressed natural gas.
Sadly, there are no other specifications to share, nor a projected price. Riversimple tells Transport Evolved however that the vehicle has been designed by a team of engineers whose previous titles have included positions at Formula 1 race teams and aerospace engineering companies. Moreover it promises, the car has been built to pass all necessary crash-testing in the European Union, features just 18 moving parts, and is being developed using an open-source methodology to encourage others to build on its technology and further development of lightweight, energy-efficient vehicles. To date, it has been has been awarded more than £4 million of total funding from a variety of sources, including the European Union and the Welsh Assembly, to continue developing and refining the Resa.
The next stage of the project is a 12-month trial of 20 prototype Rasa hydrogen fuel cell cars in the UK, where the cars will be offered to individuals on a case-by-case basis, dependent on their proximity to fuelling infrastructure and suitability for the project. After that, Riversimple promises production vehicles will hit the market in 2018.
If we’re honest, we can’t see cars like the Riversimple Resa reaching mass-market appeal. Why? The small size, limited top-speed and funky design won’t bode well with the average car buyer, especially in car-mad countries like the U.S.
But as a reminder that cars don’t all have to be large, gaz-guzzling and excessive in every way? We think it’s an excellent wake up call.
You can also support us directly as a monthly supporting member by visiting Patreon.com.