Greentech Media

Green transportation technologies refer to both the cars themselves and to what makes them move forward (and backward - or up and down). While vehicles are about as high up on the value chain as you can get, their key components are innovative green power sources that are lightweight, durable, high-performance and long-lasting. The trajectory of green vehicles is advancing away from fossil-fuel-only or fossil-fuel hybrid vehicles toward vehicles that use a combination of on-board electricity generation, biofuel and standalone electricity storage.

Bringing zero-emission vehicles (ZEVs) to commercial scale is dependent on increasing the storage capacity of batteries while decreasing their size and weight, increasing the availability of fuel for fuel cells and producing carbon-neutral biofuels on a level equivalent to gasoline. Growth trends in the transportation segment are all leading toward commercial-scale ZEVs. Technological issues aside, a number of growth-impeding infrastructure deficiencies exist. Funding and investment for biofuel-production facilities and distribution infrastructure are scarce, which limits the wide-scale reliability of vehicles reliant on these fuel sources.

Key Components

• Battery - Lightweight, high-density, quick-charging batteries are one of the key technologies competing to power electric vehicles. Rechargeable batteries in battery electric vehicles (BEVs) accelerate quickly and are able to achieve high speeds. BEVs with regenerative braking allow for battery-energy conservation, increasing distances between charging. One factor holding back wide-scale deployment of BEVs is recharging speeds and capacities. Continued research into fast-charging vehicle-grade batteries, as well as infrastructure investment for vehicle charging, is required before BEVs make significant inroads.
  • Lithium Ion (Li-ion)- Li-ion battery power systems are found in most BEVs, such as the Tesla Roadster and the Smart Car. These batteries are durable and can be made into virtually any shape, which makes them especially useful for installation in tight spaces within cars. Li-ion batteries also have a cycle durability of 1200, high-energy density, fast recharge rates and rated distances of between 250 miles and 300 miles per charge. Despite these aspects, li-ion batteries require a number of internal safety measures to prevent overheating or combustion that take up increased space within the battery. Li-ion batteries have time-dependent life spans and they begin to deplete soon after production.

  Lithium Ion (Li-ion)
  A123Systems	Valence Technology
  AltairNano	Lion Cells

  • Lithium Polymer (LiPo) - LiPo batteries are the next evolution of Li-ion batteries. Their fundamental strength is in the lack of a hard metal casing, which makes these batteries considerably lighter than their Li-ion predecessors. The newest technology extension of LiPo is the thin-film polymer electrolyte battery, which has a higher energy density than Li-ion and which use thin-film plastics to make them smaller and more flexible. LiPo batteries are also considered safer than Li-ion batteries. Where the primary electrolyte in Li-ion is suspended in a solvent, LiPo batteries hold electrolytes in a solid-state composite. LiPo batteries are currently deployed in electric bicycles, but continued research is needed to bring these batteries into BEVs.

  Lithium Polymer (LiPo)
  Sion Power	>Protanium

  • Nickel Metal Hydride (NiMH) - NiMH batteries appeared in the first modern BEVs, including the GM EV1 and the Honda EV Plus. Compared to nickel cadmium batteries, NiMH batteries have a higher energy density and lower observable memory effects – they maintain their whole charge capacity for longer. NiMH batteries also have a low internal resistance, which allows them to maintain an almost constant voltage output. However, NiMH batteries are heavier compared to Li-ion and LiPo while also having lower charge-cycle durability. These batteries are used in the Toyota Prius and the Honda Insight.

  Nickel Metal Hydride (NiMH)

  ECD Ovonics

• Fuel Cell - Fuel cells convert electrochemical energy into electricity, which is used to power an electric traction motor. Fuel cells work by combining a fuel (hydrogen, methanol) with an oxidant (oxygen) that then reacts across an electrolyte membrane. These systems can work almost continuously as long as they are provided with a constant stream of fuel.
• Proton Exchange Membrane Fuel Cell (PEM) - PEMs are the most widely used type of vehicle fuel cell. These use electricity produced from hydrogen (like other fuel cells), but are able to do so at low-temperature and low-pressure ranges, which makes PEMs ideal for use in smaller cars. PEMs, like most fuel cells, require reformed hydrogen, which must be passed through an extremely hot, highly pressurized catalyst within the vehicle before it is injected into the fuel cell.

Proton Exchange Membrane Fuel Cell (PEM)
Giner Electrochemical Systems, Inc.	Ballard Power Systems

• Direct Ethanol Fuel Cell (DEFC)- DEFCs use non-reformed ethanol to feed into a fuel cell. By not reforming the fuel, these systems do not require a catalyst, which makes for easier storage without pressure or temperature requirements. DEFCs are also promising because they rely on planned or preexisting ethanol distribution infrastructure, which is more of a reality than a hydrogen distribution infrastructure. DEFCs have limited efficiencies and power densities, but the possibility of widespread non-hydrogen fuel cells is a promising opportunity.

Direct Ethanol Fuel Cell (DEFC)

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