Jaguar Introduces C-X75 Gas Micro-turbine Extended Range Electric Vehicle Concept
30 September 2010
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| The C-X75. Click to enlarge. |
Jaguar has unveiled the C-X75 concept, an extended range electric vehicle that uses twin gas micro-turbines from Bladon Jets to power two switched reluctance generators from SR Drives. (Earlier post.) Traction is provided by four 145 kW (195 bhp), 400 N·m (295 lb-ft) traction motors at each wheel for total drive power of 580 kW/780 bhp.
The plug-in, electric drive supercar has an all-electric range of 110 km (68 miles) plus a potential top speed of 330 km/h (205 mph), acceleration from 0-100 km/h (62 mph) in 3.4 seconds, and 80-145 km/h (50-90 mph) in 2.3 seconds. Active aerodynamics allow for a simple fuselage section that remains stable at very high speeds. The plug-in will produce 28 grams of CO2 per kilometer on the EU test cycle, according to Jaguar.
The mid-mounted 70 kW (94 bhp) micro gas-turbines can generate a combined 140 kW (188 bhp) to charge the batteries and extend the range of the car to 900 km (560 miles)—or, when in Track mode, provide supplementary power directly to the electric motors. The four electric motors provide torque-vectored, all-wheel drive traction and grip, which Jaguar deems essential in a car that produces 1,600 N·m (1,180 lb-ft) of torque.
The single-speed transmission has a final drive ratio of 3.1:1.
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| C-X75 powertrain. Click to enlarge. | C-X75 airflow. Click to enlarge. |
The driver and passenger are seated ahead of a sealed airbox that houses the micro gas-turbines. The seats are fixed to the bulkhead as in a single-seater racing car, and air to feed the turbines passes smoothly around them via channels in the structure of the body. With the seats anchored in place, the steering wheel, controls, main binnacle and pedal box all adjust towards the driver.
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| Micro-turbine genset diagram. Click to enlarge. |
Micro-turbines. UK-based Bladon Jets achieved a recent breakthrough in producing the multi-stage axial flow compressors—the technology used on all large gas turbines—on a miniaturized scale and to very high tolerances. This increased the compression and efficiency of micro gas-turbines to the point at which they can be viewed as a realistic power source. Each of the micro gas-turbines weighs just 35 kg and produces 70 kW of power at a constant 80,000 rpm.
Because the exhaust gases form part of the active aerodynamic package, Jaguar has utilized a specialized zirconia-molybdenum coating. This advanced heat-resistant coating is regularly used in Formula One cars and is applied in a plasma spray to the carbon-fiber diffuser to protect it from the exhaust gases.
Turbines offer a number of advantages over a reciprocating piston engine when powering range-extending generators, Jaguar says. With fewer moving parts and air bearings, turbines do not need oil lubrication or water-cooling systems, all of which offers considerable weight-saving benefits. They can also be run on a range of fuels including diesel, biofuels, compressed natural gas and liquid petroleum gas.
Turbines reach their optimum operating speed and temperature in seconds and so can be used in short bursts to top up the batteries without compromising fuel consumption or life-cycle. Coupled to two switched reluctance generators supplied by SR Drives, the turbines operate either in sequence or together, depending on energy needs, to charge the batteries—or provide power directly to the electric motors—as dictated by the propulsion system supervisory system.
Active aerodynamics. Jaguar is already aiming to reduce the drag coefficient of its future models in order to increase fuel efficiency. The C-X75 presented the additional challenge of managing the high volume of air required by the turbines. To achieve this active aerodynamics have been utilized for the first time on a Jaguar.
By opening the front grille and brake cooling vents only when necessary, Jaguar has increased the design’s aerodynamic efficiency. At the rear corners of the car vertical control surfaces automatically engage at higher speeds to direct airflow aft of the rear wheels for increased stability and efficiency.
The carbon-fibre rear diffuser, a crucial element in guiding airflow under the car and creating downforce includes an active airfoil, which is lowered automatically as speed increases. Vanes in the exhaust ports then alter the directional flow of the gases to further increase the effectiveness of the Venturi tunnel.
The C-X75 has a drag coefficient of 0.32 Cd and active downforce created through the use of an underbody Venturi. The underbody Venturi and directional exhaust gas control kept the car as sleek, compact and low as possible while still generating large amounts of grip and downforce. Indeed, the movement of air itself was one of the principal drivers behind many of the design cues that were incorporated into the bodywork.
We wanted to emphasize how the air makes its way not just over the car but is also channelled into the rear airbox. When operating at 80,000 rpm, each gas-turbine requires 35,000 liters of air a minute which means we needed a series of carefully honed intakes.
—Principal designer Matt Beaven
Advanced lightweight aluminium construction techniques provide weight-saving and economy benefits. Additionally, up to 50% of the metal content is recycled.
Batteries. Battery technology is currently the greatest limiting factor in the development of high-performance electric vehicles with a realistic range. Jaguar says its engineers are currently carrying out research with leading battery suppliers into the next generation of power cells in order to find the best compromise between energy and power densities. The batteries used in the C-X75 are of a composition which offers benefits in terms of weight, lifecycle, energy density and safety.
Braking. The C-X75 is fitted with the brakes used on the supercharged XFR which in 2009 became the fastest Jaguar ever, achieving 363 km/h (226 mph) at the Bonneville Salt Flats in Utah. In this application, regenerative braking technology on all four wheels helps recharge the batteries during driving. The 380 mm internally ventilated front discs and 345 mm rears are covered by polished alloy wheels of 21 and 22 inches wrapped in bespoke hand-cut Pirelli rubber measuring 265/30 ZR21 and 365/25 ZR22 front and rear respectively.
I've seen youtube videos of these little microturbines at work and there's a big problem from what I've seen that isn't being mentioned - noise. Obviously, running in all-electric mode the vehicle will be quiet, but I can only imagine how much noise is generated when the microturbines are running at 80,000 RPM. Not very practical for suburban driving.
Posted by: ejj | 30 September 2010 at 06:29 AM
"..(50-90 mph) in 2.3 seconds." WOW, what about when the wings are on..
Posted by: kelly | 30 September 2010 at 07:36 AM
For racing car noise would be not an issue. One question - why such car needs brakes. The electric motors are so powerful that will be able regeneratively stop car without any other brakes.
Posted by: Darius | 30 September 2010 at 07:56 AM
ejj
Can you imagine how much noise an ICE makes without a muffler?
Posted by: Lucas | 30 September 2010 at 07:57 AM
How do you muffle a turbine for a consumer application? Isn't there a heat issue?
Posted by: Reel$$ | 30 September 2010 at 08:52 AM
Why two turbines instead of one? Doesn't gas turbine efficiency improve with scale, so one larger unit should be more efficient than two smaller ones with the same net output? I know it's just a concept, but still.
Posted by: Nick Lyons | 30 September 2010 at 09:19 AM
I've been hear a lot about problems of unsprung weight with wheel motors. I wonder how they deal with that?
Posted by: joewilder | 30 September 2010 at 09:28 AM
I'm surprised they don't show a recuperator in the exhaust stream for the turbines to preheat the compressor air. This would improve efficiency as well as reduce audible noise.
Posted by: Mannstein | 30 September 2010 at 09:47 AM
The motors appear to be in board driving shafts to the wheels. I suspect that space was a concern, which may be why they did not use a recuperator.
Posted by: SJC | 30 September 2010 at 10:06 AM
"a sealed airbox that houses the micro gas-turbines" and "near silent running" http://www.bladonjets.com/pdf/jlr-article.pdf
This almost parallels the Mitchell/Spitfire aircraft legacy we owe much of our freedom to, sadly even including the ravages of the designer's cancer.
One way or another - via electric motor/battery, Wankel, jet, fuel cell extenders, etc - the thousand moving part ICE power train/oil strangle hold will end.
Posted by: kelly | 30 September 2010 at 10:06 AM
This is a performance car, I don't think efficiency was high on the list. Any way we can reduce oil imports is a way to a more secure energy future. If OPEC reduces supply to drive up prices, that is more incentive to substitute.
Posted by: SJC | 30 September 2010 at 10:31 AM
Seeing (actually hearing) will be believing with respect to the "near silent running".
Posted by: ejj | 30 September 2010 at 11:23 AM
"This almost parallels the Mitchell/Spitfire aircraft legacy we owe much of our freedom to..."
Which freedom are we talking about?
You mean the one East Europeans enjoyed after Uncle Joe took over that part of the continent?
Or how about the one which makes it a crime in Europe to question certain aspects of WWII?
Posted by: Mannstein | 30 September 2010 at 11:53 AM
This is a car tech tour de force with 32 mpg.
One could detune one of the two jets, use half of one of the four motors - and still have a quick, >64mpg Corolla drive train (besides maybe 100 mi. e-range). http://www.dailymail.co.uk/sciencetech/article-1316273/E-Type-Jaguar-supercar-200mph-electric-hybrid-jet-engine-costs-200K.html
Posted by: kelly | 30 September 2010 at 12:14 PM
The microturbine can be made quiet. I got a chance to drive the Whisper SUV and it was wonderful. The first day I drove it, they were working on things without all the sound proofing on and it was VERY loud. But they sealed it back up with all the cladding the next day and it was very quiet and a pleasure to drive.
The strange part is that the Capstone controller put out more noise than their microturbine itself. Capstone have since redesigned it so it's smaller and quiet but I haven't heard the new ones yet to verify that nor have I been around a car with the Bladon turbine for comparison.
Posted by: DaveD | 30 September 2010 at 01:20 PM
Try not to lose sight that this is a "concept". Though feasible, it relies on multiple unproven claims of technical breakthrough. Moreover, it does not make a compelling business case which is why we won't see it in production. Its fast, but there are a dozen other real cars on the market today with the same of better performance, not to mention it is only fast until the batteries are depleted which will take all of a minute of so. Once the gas turbines are powering it as it series hybrid, it only makes 188hp. As for efficiency, It may be a cycle beater on test due to its all electric operating potential, but in charge sustaining mode, it will be pretty bad. Small gas turbines are horribly inefficient reducing the specific power density larger gas turbines are famous for. To add further complication, the unrecuperated Brayton cycle is very inefficient from a specific fuel consumption perspective. Bladon makes numerous unfounded claims of technical breakthroughs to resolve both of these issues, but a review of their IP portfolio, including applications not yet granted shows no evidence of breaking new ground. This car would be much more efficient with a conventional recip of the same power level. In the end, its main attribute is its unique, but not differentiated powertrain. Tata may need this concept to gain attention to its premium brand now that its under new colonial ownership, but it doesn't need a production version to keep selling Jags.
Posted by: UnnaturallyAspirated | 30 September 2010 at 02:03 PM
Finally I hear one sober voice from UnnaturallyAspirated
Posted by: CarCrazy | 30 September 2010 at 02:34 PM
"..not to mention it is only fast until the batteries are depleted which will take all of a minute of so.." A 68 mile range battery can power closer to an hour and one seldom drives WOT more than a few seconds at a time.
With most of a century on and off the track, Jaguar likely stands behind the C-X75 specifications they released and their reputation.
Posted by: kelly | 30 September 2010 at 02:43 PM
@ kelly....
As for Tata's (Jaguars) specifications, the maths all add up. its simple physics. The point is that there is more to it than the specifications that they've posted. Its just my opinion, but this concept is a poser. You can drive it @ WOT for about 90 seconds, long enough to reach top speed once, but it won't run a track event, and will struggle to complete most Auto-X events. It will produce good CO2 numbers on the EU cycle but its well known that neither the NEDC nor FTP75 represent real world driving. In charge sustaining mode it will be about ~15% thermally efficient, hardly better than the 580kw reciprocating engine they seek to replace. Its like a hybrid between a Ferrari with a 1 gallon tank and a coffee straw for a filler and a Prius with a 2 spark plugs removed.
Posted by: UnnaturallyAspirated | 30 September 2010 at 04:35 PM
Holy 2010 BatMobile!!! One even Adam West would have approved, (or Christian Bale, for the younger generation).
This twin-turbine electric rocket on wheel beats the 1960's BatMobile handily, sporting TWO turbines, vs. the original BM having only a single fiery exhaust.
And its exhaust emission will be so clean, and will be so quiet while on the all-electric mode that Gotham will not even detect its passing by...assuming the new sci-fi stealthy paint job that'll make it nearly invisible! the more so that the Dynamic Duo can get to their job discreetly.
Seriously, this is a major achievement in "life in the fast lane." A marriage of eco-conscience and testosterone with a serious dose of finness.
Posted by: Roger Pham | 30 September 2010 at 07:44 PM
" In charge sustaining mode it will be about ~15% thermally efficient, hardly better than the 580kw reciprocating engine they seek to replace."
If this is true, how does 580 kw get 500mi/15gal. = 32 mph?
Typically, it only takes 20 hp to maintain 60 mph, yet 200 hp to get there within 10 seconds, with ICE using a thousand movings parts and ~20% thermo efficiency throughout operation.
Meanwhile, an electric drive train operates at 90% thermo efficiency and drops transmission weight/friction/part count/complexity/expense with instant 100% torque.
Per an average 40 miles/day travel, an extender - and it's liquid fuel expense - should only be needed for 10% of all trips, and WOT under 10% of that - which the battery can easily buffer.
Maybe it can be thought of like a welder duty cycle. 100% is perfect, with 100% expense, but few of us need (or can hold) a bead (or WOT) more than 10% of the time.
So why pay the extra 90% in hardware or additional energy costs, unless maybe auto/oil has kept it our only market option for a hundred years.
Posted by: kelly | 01 October 2010 at 02:15 AM
I think you all are over-analysing it: This car is pure $ex-on-wheels.
Posted by: ai_vin | 01 October 2010 at 08:58 AM
@ kelly...
if you are technically savvy, grab a thermodynamics book and run the calcs on a simple Brayton cycle (no recuperation, intercooling and single stage expansion) and you'll see that 15% if a pretty good value for BTE. Modern reciprocating engines at similar power levels are easily +30%. ie. typical 4cyl turbodiesel can achieve peak BTE of +37%. Gasoline engines are less efficient and more sensitive to off load cases, but still hover around 30% at peak island. The Gen III Prius engine is actually about 35% for a fairly wide operating region.
Not sure where 580 kw, 500 mi/15 gal comments comes from. it doesn't take 580 kw to drive 32 mph and neither a gas turbine nor recip will go 500 miles on 15gal producing 580kw.
Regarding average driving conditions, i don't disagree with you. Virtually no consumer really needs the performance that is offered by the vast majority of vehicles on the road.
Posted by: UnnaturallyAspirated | 01 October 2010 at 02:21 PM
Per the link above, http://www.dailymail.co.uk/sciencetech/article-1316273/E-Type-Jaguar-supercar-200mph-electric-hybrid-jet-engine-costs-200K.html - the C-X75 goes 500 miles on a 15 gallon tank (32+mph) while the micro-turbines charge the battery that powers the motors.
Cars are only practical with an electrical (starter/battery) system. For decade(s) now, a enlarged electrical system(eliminating the expensive transmission) could cover the typical daily drive. A extender could be added - cheap and only used, at optimized rpm, for a few long trips annually. After all, over 50% of the world's population lives in urban area's and distances.
Posted by: kelly | 01 October 2010 at 07:27 PM
@ Kelly....
"If this is true, how does 580 kw get 500mi/15gal. = 32 mph?"
With simple math, you can show that given their claimed Cd of .32, reasonable frontal area of ~2.2m^2 and rolling resistance of 0.012, it takes ~5.5kw to maintain 32mph.
Likewise, 15 U.K. gallons of diesel fuel contain ~2,200MJ of energy.
to travel 560miles at 32 mph,it takes ~15.5hrs at ~5.5kw which equates to ~350MJ of energy.
346MJ of work from 2,200MJ of potential energy = ~16% efficient from fuel to shaft power.
this assumes they start with depleted batteries. if not, then the efficiency number goes down more.
The reality is that their own numbers agree with physics which prove that it is not an efficient solution and a simple recip would be a substantially more efficient heat engine for this application.
Posted by: UnnaturallyAspirated | 01 October 2010 at 09:53 PM