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Posted on May 25, 2011 by  & 

Range extenders for hybrid vehicles - second vs third generation

We are in the decade of the hybrid electric vehicle despite the fact that most off road and underwater vehicles are pure electric. That includes most forklifts, golf cars and mobility vehicles for the disabled plus Autonomous Underwater Vehicles AUVs and personal submarines. Indeed, most electric aircraft are pure electric as well. The reason is that these are mainly small as are electric two wheelers which are almost all pure electric as well. Small vehicles rarely need to travel long distances. In addition, these pure electric vehicles are often used where a conventional engine is banned as on lakes and indoors or where it is impracticable as with underwater vehicles. By contrast, half the electric vehicle market value lies in larger road vehicles, notably cars, and here the legal restrictions are weaker or non-existent and range anxiety compels most people to buy hybrids if they go electric at all.

Largest sector by value

By value, hybrid cars are now the largest electric vehicle sector and, since they will be with us for at least fifteen more years, improving the hybrid technology is of major interest. Indeed, it will benefit the rapidly growing sectors of hybrid buses, trucks, boats and aircraft. For example, the new IDTechEx report, Electric Buses and Taxis 2011-2021 forecasts over 91,000 hybrid electric buses being made in 2021. They will sell for up to 65% more than the price of conventional buses but still have lower total cost of ownership over life. Most importantly, the local and national governments and transit companies buying buses are determined to go green. That means a global hybrid bus market of around $40 billion in 2021 by our analysis. Equivalent forecasts for hybrid cars can be found in the IDTechEx report, Hybrid and Pure Electric Cars 2011-2021.

Here come range extenders

All that is dependent on progressing from internal combustion engines not designed for this purpose to engines optimised for use in hybrid power trains. Such vehicles will that have the substantial all-electric range demanded by users, having batteries storing more energy and plug-in capability. That will become the case for land, water and airborne hybrid vehicles.

Second or third generation?

The more battery/ less engine scenario is encompassed in the term range extended hybrid. These second generation engines retain piston driven, internal combustion technology. By contrast, third generation hybrid engines dispense with pistons in order to improve environmental credentials even more and offer further benefits of size, weight, cost, reliability, economy and alternative fuels or at least some of these. The question is whether we shall jump straight to these third generation engines for hybrids. After all, they are already seen in some buses and aircraft and a Suzuki two wheeler and they are in trials on many other platforms.
Taking the second generation approach, Lotus, the DLR German Aerospace Agency and others have designed simplified "monoblock" engines that are more economical in fuel use, lower cost to buy, less polluting, space saving and potentially more reliable.
Taking the third generation approach are fuel cells from Intelligent Energy in the UK and others and Bladon Jets mini turbines. Bladon Jets in the UK is an investment of Tata Motors Europe, which will incorporate two of these devices in each of its planned Jaguar CX75 electric supercars. Daimler AG subsidiary Mercedes Benz in Germany will soon put on sale the world's first electric car with a fuel cell range extender. In Italy, ENFICA-FC has successfully flown its two seater aircraft with a fuel cell range extender and AeroVironment in the USA has fuel cell extended Unmanned Aerial Vehicles UAVs in the form of aircraft, a Northrop Grumman version being a fuel cell range extended electric airship.
Could these third generation hybrid power trains enter mass markets soon and obsolete second generation designed-to-purpose ICE range extenders before they are launched? The answer seems to be no. There is now evidence that there is some window of opportunity for the interim product - perhaps upgrading the impressive Adam Opel Ampera in Europe, for example.

Second generation success

Lotus Engineering has recently received enquiries from several OEMs to take 5,000-10,000 units of its simplified internal combustion engine annually. This device is specifically optimised for the near constant revs and torque of a hybrid vehicle range extender. The new Lotus Range Extender is a three-cylinder monoblock motor, meaning the head is inseparable from the block, which lowers weight, reduces production cost, and eliminates a major point of potential failure - the head gasket, bane many of today's hybrid engines. In addition, the exhaust manifold is cast into the block, for the same reasons as the integral head.
Now Lotus Engineering in the UK has told Autocar that it has received "significant" interest in its range-extending engine for series hybrid passenger cars. Chief Project Engineer Lee Jeffcoat told the publication that there is interest from several companies in acquiring 5,000 to 10,000 units annually, including three major passenger car manufacturers. He added that some small-scale automakers have also inquired about taking between 100 and 1,000 units a year. The 3-cylinder gasoline (petrol) engine has been undergoing testing in a range of vehicles, including Jaguar's Limo-Green, though the planned Jaguar supercar will use Bladon Jets mini turbines as range extenders. The lotus product is also being tested for Proton's EMAS, and Lotus Cars' Evora 414E hybrid concept car. This, and consultation with potential customers, has led to changes to the design. One example of this is that the engine can now be installed at any angle between vertical or horizontal.
Lotus Engineering is also preparing a supercharged variant alongside a naturally aspirated version. When supplies commence, production will be outsourced to Spain's Fagor Ederlan Group. It remains to be seen which company will be the first to use this engine in a production vehicle.

Europe in the lead

The Europeans are therefore leaders in range extenders for hybrids as they gradually transmogrify into pure electric vehicles. The Europeans are fairly strong in traction electric motors but the Europeans are weak in the traction battery technology required for all forms of electric vehicles, their efforts, while impressive, being early stage Third Generation such as Oxis Energy lithium sulphur batteries, or niche such as military and other traction batteries from SAFT in France and ABSL in the UK. Volume production of today's second generation lithium-ion batteries being left to the East Asian giants such as Panasonic, LGChem and Samsung, with automotive leader Toyota making its own.

Unique event

A unique event looking at the whole picture Electric Vehicles - Land, Sea & Air Europe 2011 will take place in Stuttgart Germany June 27-28 as a two day conference and exhibition. Most of the organisations mentioned above are presenting. Optional masterclasses and visits to local centres of excellence in the subject are offered on the day before and the day after this event. There will be an investment session and an awards dinner. It is not too late to apply for an award. See, contact Teresa Henry if you wish to be involved in any way.
Top image of Lotus Range Extender, source: Lotus

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Posted on: May 25, 2011

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