The Wright Stuff: From Tesla to Trash

In-depth

17 Feb

As recently as five years ago the thought of electric trucks had probably not entered the average truckies mind and vocabulary. That’s certainly not the case today.

Today it seems, the talk in trucking is all about electric. Major manufactures around the world are spending multiple $ millions to bring the industry into the battery age. Back in 2017 I was invited to a presentation by one Ian Wright who was streets ahead of the field those five years ago.

Ian’s solution to battery power was to add a gas turbine engine. His is a fascinating story….

“Imagine if a diesel engine manufacturer announced a new powertrain providing up to 60% fuel savings and a 90% reduction in emissions. Wouldn’t that change the world? Well, that is exactly what we have done.”

**Turbine - 1,000 degrees/86,000rpm. No emissions.**

These were the opening words of Ian Wright, co-founder and CEO of Wrightspeed. New Zealand born, living largely in America and with an Australian accent, Ian was also a co-founder of Tesla in 2003, before Elon Musk (who was the first investor) took control. Ian’s company make range extended electric powertrain systems – the complete replacement of diesel powertrain and accessory drives, currently used in refuse (garbage) trucks and city transit buses.

The wheels are driven with a conventional axle but there are two electric motors, two four-speed transmissions and a high-efficiency final drive, so the wheels are actually driven independently of each other. The same applies to the second axle. There is a battery pack configured in various different ways and there is a gas turbine engine driving a generator, plus fuel to extend the range.

“We don’t actually change any of the systems that would affect certification of the vehicles. We don’t touch the brakes, we don’t touch the chassis, we don’t touch the suspension - it’s just the powertrain.”

Equipped thus, the garbage vehicles produced to date are on an equal weight footing with conventionally driven product. The 4 speed transmission was designed in-house from scratch and was, unexpectedly, the most difficult part of the equation. These transmissions work without clutches or torque converters. “Without a transmission these trucks wouldn’t do 30km up a shallow gradient. In a Tesla car it’s not a problem but it is here.”

“We went to Ricardo in UK to do the first one which cost $650,000. This is a company that designs Formula One transmissions. The damn thing wouldn’t stay in gear. The bearings failed after 10 hours and it got way too hot. We have figured out how to do it now and we have a patent on our gearing.

“Garbage trucks are probably the best drive-cycle for us because it’s the hardest drive-cycle. The average US garbage truck does 210km a day. It does a thousand hard stops. (The drivers are either full on throttle or full on brake). Some of them are actually triggering the ABS for most of those stops. We see 23,000 ABS events a month. So if you want to look at heavy vehicles and say which ones would be good for electrification, find out how long the brakes last. What they are doing is they’re taking the energy of the diesel, turning it into kinetic energy and throwing it away on the brakes thousands of times a day. It’s a very inefficient use of a powertrain. In America a long haul truck uses around 33litres/100km. The same powertrain in garbage trucks uses (national average) 94litres/100km.”

The Wrightspeed powered garbage trucks save 60% on fuel, save engine and brake maintenance, are very quiet, reduce emissions by up to 90% emissions, match diesel performance, pays for itself in less than four years and has a 10 year design life - all compelling arguments for the product.

A battery-only system would be prohibitive in weight - about half the payload of the truck - and would cost around $500,000. Hence the trucks needs batteries, plus a range extender which means better performance with no range limitation.

“The Nikola is a battery powered EV truck with a fuel cell range extender. It doesn’t work for long haul. The fundamental problem with fuel cells is that they need hydrogen and hydrogen is not a naturally occurring fuel, it has to be manufactured by electrolysing the water with electricity. It is about 70% of maximum theoretical efficiency so you have lost 30% efficiency already to get hydrogen. Then you go and compress the hydrogen at 10,000 psi which loses another X percent. Then you put it through a fuel cell which has a theoretical maximum efficiency of about 40%. Over that whole cycle you’re only 25% efficient. There is also no hydrogen refuelling infrastructure. Through a battery you get 98% efficiency.”

“The Tesla Semi is battery-only with a 500 mile range. It is a single speed with 1000 hp. It has a 1.5 MWh battery pack which costs $255,000 and there is a 10,000lb payload loss. The cycle life of these batteries is also only about 500 times. Case closed.”

By way of comparison a Mack MP7 motor with Allison transmission weighs in at 1600kg and puts out 325 hp. The Wrightspeed Geared Traction Drive (GTD) weighs just 208kg and puts out 600 hp continuously. With one per axle, the truck has an available 1200 hp. Whilst the motors can make up to 1200 hp, drive power is kept to 425 hp which is reached at 8km/h. The differential between the two is used for braking and regenerative power.

The Wrightspeed designed and patented Fulcrum Turbine Range Extender Generator is a little gas turbine which runs at about 1000°C and will run like that for 10,000 hours at 86,000 rpm. Running on diesel or natural gas no after-treatment is required due to the massively high temperatures generated. With one moving part it is also very low maintenance.

“We use a turbine for the range extender for the same reason that turbines took over completely in aviation in the 1950s.

“Why didn’t it take over in cars? Chrysler made a turbine car in 1962. The problem with cars is that most of the time you don’t need much power. It only takes 10 kW to drive down the road at 55kph. Turbines are only efficient at full power. The fuel flow at idle is about 50% of what it is at full power therefore the consumption if you are driving wheels with them is terrible.”

“We are not driving wheels with a turbine, we’re driving a generator so it’s the advent of the high-powered batteries and the electric drive that makes the system viable. The turbine simply drives the generator at full power until the batteries are recharged and then it turns off. It’s also very quiet. The magic part is that it is so clean. We can meet California emissions with no after-treatment at all. We could meet emissions with a gasoline burning piston engine but we wouldn’t get the engine durability. We could get better efficiency using a diesel engine driving the generator but we couldn’t meet emissions so a turbine gives you the best of both worlds. It comes in only when needed and can recharge the batteries up to 80% in six minutes.”

Whilst Ian doesn’t see the use of diesel for long haul disappearing anytime soon he believes that in urban situations, such as garbage trucks and buses, diesel will all but disappear.