## Israeli Microturbine-Based Range-Extended Electric Vehicle Startup Lands $12M Series A Round ##### 25 April 2009  Drawing of the proposed advanced microturbine. Source: ETVM Click to enlarge. ETV Motors Ltd. (ETVM), an Israeli start-up developing a range-extended electric vehicle (REEV) technology combining a novel dual-power micro-turbine and a new high-voltage lithium-ion battery chemistry, has closed a US$12-million Series A investment round. The round was led by The Quercus Trust of Newport Beach, California. New York-based 21Ventures LLC co-invested.

The investment enables ETVM to move ahead with a multi-year research and development program in which it is partnering with universities and development organizations.

We believe that REEVs are the optimal approach. Our micro-turbine on-board charger and 4.7V lithium-ion cathode chemistry will facilitate the coming generations of environmentally-friendly, cost-effective, light-weight and safe electric vehicles.

—Dror Ben David, chief executive of ETVM

Microturbine. ETVM is developing its own microturbine. The ETV microturbine will operate on RQL (Rich-Quench-Lean) principles and will have the unique property of achieving optimum efficiency at two operating points. This “dual mode” property will provide a number of degrees of freedom when matching the microturbine to various drive cycles and vehicle categories. Other features of the ETV microturbine include:

• Proprietary valving and duct design results in minimal pressure drops;

• Advanced heat exchanger/recuperator resulting in ultra-high thermal efficiencies (>90%) with low pressure drops. (The combined hot and cold pressure drops will be less than 8.5% of maximum cycle pressure);

• Implementation of ceramic regenerative heat exchanger and turbine enabling operation at higher turbine inlet temperatures.

In simulation exercises, ETVM found that the fuel costs for ICE-powered REEVs in typical urban environments will be up to 50% more expensive than those powered by microturbine on-board chargers.

ETVM estimates that its first prototype P1 turbine, with an efficiency that outperforms the present state of the art by approximately 30%, will be fully functional in Q2 2010.

Targeted Characteristics of Prototype and Production ETV Microturbines
P1P2Production
Power (dual mode) kW 12/45 13/48 20/60
Efficiency % 37-38 38-44 45-50
Weight kg 120 100-110 100-120
Rotational speed rpm 80,700 80,700 tbd
Turbine inlet temperature °C 975 1,050 1,250-1,350
Turbine   Metal Metal Ceramic
 Ragone plot showing expected position of the ETV 4.7V and 3.2V cathode chemistries relative to the commercial Lithium-ion chemistries. Source: ETVM Click to enlarge.

Battery. On the battery side, ETVM is working in collaboration with the electro-chemistry team at Bar Ilan University to develop a 4.7V Lithium Manganese Nickel Oxide (LMNO) cathode. The proprietary and patent-pending solutions demonstrated in the laboratory involve the following strategies:

• Ex-situ nano-scale sono coating of the LMNO raw materials
• Novel LMNO synthesis process
• In-situ coating of cathode with nanometric polymeric layers

The new material overcomes the problems with higher voltage spinel materials, according to ETVM, which include oxidation of the electrolyte solvent and partial dissolution of metal ions in the cathode and damage of the anode and cathode SEI structures.

The resultant LMNO cathode may be coupled with a range of anodes. ETV is working on two cell chemistries: LMNO/Graphite to form a 4.7V cell; and LMNO/LiTiO to form a 3.2V cell.

ETVM is building a proof-of-concept demonstrator REEV (Range-extended Electric Vehicle), based on a modified Prius, to serve as a test vehicle for the company’s ongoing development work. The company’s researchers and engineers will begin testing the proof-of-concept microturbine-based REEV towards the end of 2009 Q2 using commercially available components.

A ceramic turbine sounds great, but I will believe it when I see it. Now a ceramic recuperator to a Rankine turbine in combined cycle might be nice, but that is another story.

Very optimistic projections, but I wish them luck. \$12M doesn't sound like much considering the engineering challenges they've set themselves.

I'm surprised they chose a Prius as a prototype platform--I'd expect them to be looking at a series-hybrid approach. Prius does give them a nice aerodynamic shape, I suppose.

Future PHEV-60, PHEV-80 or PHEV-100+ may not need very large nor very durable gensets.

Since those PHEVs will run mostly on precharged batteries, a much lower weight, lower cost, lower quality, but very easily exchangeable genset could do the job.

A very small (plug-in) 10 to 15 KW genset should be suffisant for most cars. Users would pick the genset size based on their driving requirements.

The huge advantage in temperature enjoyed by pottery is nice but drawbacks include fragilty to thermal and physical shock.

As Nick says, challenges are huge.

I assume this is a long term "multi-year" science project since a range extended vehicle hardy needs such a a gold plated gen set.

It would physically be impossible to achieve real life BTE (efficiency) of 37-38 % in Prototype I, and 45-50% in the Production model, in a 120-kg size micro-turbine. Count on no more than 25% BTE as with the Capstone turbine, and perhaps no more than 30% with the ceramic turbine blades of the Production model.

There are inevitable losses due to air friction drag on the turbine blades and pressure loss due to leakage via the lateral edges of the micro-turbine blades. As the turbine gets larger, these losses will be come smaller due to operation at significally larger Reynolds number and smaller clearance gap-to-dimension ratio associated with the larger turbines.

Larger gas turbines (power plants) has much higher pressure ratios due to the much larger number of compressor stages and expansion turbine stages (not practical in smaller gas turbine, due to costs). This necessitate higher turbine-inlet temperatures, using "unobtainium" metals (very expenive) plus internal cooling of the hollow blade by air, not possible in much smaller turbine blades.

Exhaust heat recuperation may be practical in a low-pressure-ratio, low-specific-power and low-efficiency gas turbines, but not practical in a high-efficiency gas turbine with higher pressure ratio and more expansion stages--unless a bottoming cycle is used, again, not practical in a micro-turbine setup.

Well Stated Roger, Unless they rewrite the laws of physics there is no way to get that kind of efficiency with an open brayton cycle on air, ceramic or not. You run into huge efficiency problems with seals and bearings the smaller you go.

I'd love to see the bearings that can withstand lots of start ups as well. These types of turbines work forever if you never stop them, they wear until the bearings reach 20K rpm or so.

Also, Capstone burned through over a billion bucks getting theirs out, 13 Mil goes quickly while developing turbo machinery.

It is not clear if this engine uses an axial flow or centrifugal flow compressor. If it is a centrifugal set up only a two stage compressor would be needed to get a reasonable pressure ratio.

Also the bearings used in this engine could be of the air foil type which require no lubrication. They are quite durable and ideal for high RPM turbo engines. Active magnetic bearings might also be used and could be integrated with the alternator. Magnetic bearings however are not well suited for the speed range they are planning to use.

Incidentally, the Japanese have been working long and hard to apply advanced ceramic materials for jet engines and turbo chargers.

Most micro-gas-turbines use centrifugal compressor due to the low manufacturing cost, and usually there is only one single stage centrifugal compressor and a single stage turbine. Slightly larger gas turbines in the 300-500 hp range may have an additional axial stage compressor preceeding the centrifugal stage.
The issue here is that any gain in efficiency and specific power by using higher pressure ratios would be offset by higher losses from leakage via the compressor clearance gap. Furthermore, higher pressure ratios will require higher turbine inlet temperatures which will then require expensive materials and elaborate internal air cooling mechanism not possible in micro turbines.

Capstone turbines utilize air bearing which requires no lubrication nor any maintenance.

For BTE's in the 40-50% range for use solely in an electrical generator, a more promising engine would be the free-piston engine powering linear electrical generators from its reciprocal motion. Mass balancing can be accomplished by bundling a number of piston-cylinder units together, whereby opposing reciprocating momentum can cancel each other out.

That is something I learned from studying reciprocating linear Stirling engines. If you have identical opposing synchronized devices you can cancel vibrations. The same principle applies here. I would agree that 2 or 4 cycle opposing sounds good, but I have yet to see high output linear alternators of a reasonable size.

Stirling engines may be the best choice for long run range extenders in buses or cars. But if such a unit is seldom used, the efficiency is of little concern. A small turbine is not likely to get the efficiency proposed. The major problem with hybrid buses is the cost of the electrical system. Batteries are a major cost issue. The ZEBRA battery is a well tested battery that is suitable for buses, and the weight may work out to be less than lithium because of the cooling lithium cells need. A single piston, large cylinder, diesel engine is likely to be the most efficient way of generating extra electricity. ..HG..

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