Toyota hybrid synergy drive®: multiple solutions for sustainable mobility

Toyota Hybrid Synergy Drive®

— Modular HSD technology: readily adaptable for Plug-in Hybrid Vehicles (PHV), Electric Vehicles (EV) and Fuel Cell Hybrid Vehicles (FCHV)

— Full Hybrid Vehicles (HV): enhanced powertrain efficiency with lower CO2 , NOx and particulate emissions than conventional engines

— PHV: practical powertrain electrification, with EV mode for city driving 
and full hybrid drive for long range capability

— EV: Toyota continues the development of short range Electric Vehicles for commercialisation

— FCHV: hydrogen fuel cells - the potential to solve environmental and energy problems, with water vapour the only emission

Although the reduction of CO2 emissions -identified as a significant cause of global warming- did not become a global issue until the 1990s, Toyota has been researching and developing environmentally-friendly mobility solutions for over 40 years in the quest for the ultimate eco-car.

Basing its approach on the concept of 'the right car, in the right place, at the right time', Toyota believes it is important to follow more than one path towards sustainable mobility.

With fossil fuels remaining the key energy resource of the immediate future, Toyota will continue to improve the efficiency of its petrol and diesel engine vehicles through the use of Toyota Optimal Drive technologies, which already benefit most of the company's model line-up in Europe. Further developments in synthetic and biofuels, diverse energy sources and battery technology pave the way for several types of eco-car to coexist in the future.

Today, Toyota's early vision has been vindicated. The last few years have seen a marked increase in the production of environmentally-friendly vehicles, and most manufacturers are now developing hybrid technology.

With 2.3 million hybrid vehicles already sold worldwide, Toyota's incomparable record of customer experience gives the company an unquestionable lead in the drive towards sustainable mobility.

Full Hybrid technology

Hybrid drive is not an alternative to petrol or diesel, but an addition, enhancing the efficiency of existing powertrains. As well as lowering fuel consumption, hybrid vehicles are particularly effective in the reduction of emissions. They produce cleaner emissions than conventional, diesel-powered vehicles and less CO2 and NOx than petrol-powered vehicles.

Named International Engine of the Year in 2004, Green Engine of the Year and Best Fuel Economy Engine of the Year for the fifth consecutive year in 2008, Toyota's Hybrid Synergy Drive® represents the ultimate synergy of high technology and environmentally-conscientious forward thinking in powertrain design.

Hybrid Synergy Drive® has been fundamental to the global success of the multiple-award winning Prius. A brilliant work in progress, three generations of the car -1997, 2004 and 2009- have seen significant improvements to successive evolutions of Toyota's full hybrid drivetrain, with system power increasing by over 30%, yet fuel consumption and CO2 emissions falling by about 25%.

The Prius now returns combined cycle fuel consumption of 
3.9 l/100 km and CO2 emissions of just 89 g - a figure unmatched by any family car.

Toyota is committed to a further reduction in the size, weight and cost of key hybrid components such as the electric motor, inverter and battery.

The launch of the Auris HSD in the heart of the C-segment presages the introduction of as many as 10 new Toyota hybrid models globally by the early 2010s, with a target of achieving worldwide annual sales of one million Hybrid Synergy Drive® vehicles within the same time frame. By the beginning of the 2020s, Toyota aims to offer all models with a full hybrid powertrain derivative.

Reinforcing Toyota's environmental lead in the drive towards sustainable mobility, Hybrid Synergy Drive® will serve as a core technology applicable to all future models. The system has been specifically designed to be modular, and is readily adaptable to use in Plug-in Hybrid Vehicles (PHV), Electric Vehicles (EV) and Fuel Cell Hybrid Vehicles (FCHV).

Plug-in Hybrid technology

In recognition of the importance of energy diversification, Toyota's Plug-in Hybrid Vehicle (PHV) programme introduces a further development in environmentally-friendly urban mobility.

Despite the environmental merits of electric cars as urban commuters, their further development is currently handicapped by the weight and size of the batteries required to offer a satisfactory range, and the lack of an adequate recharging infrastructure.

Toyota has therefore determined that, in light of current battery development progress, plug-in hybrid drive is the most feasible short- to mid-term technological solution to the electrification of powertrains.

The Prius Plug-in Hybrid represents a significant expansion of the Hybrid Synergy Drive® system's capabilities. It is a full hybrid vehicle in which both the electric motor and petrol engine can drive the wheels. A fully electric, EV mode is employed for shorter journeys, while the hybrid powertrain's petrol engine awards the Prius Plug-in Hybrid true long range capability.

The Prius Plug-in Hybrid marks the introduction of lithium-ion batteries in a Toyota hybrid vehicle for two key reasons: Firstly, having superior volume energy density, they are more compact than their nickel-metal hydride counterparts, offering a significant increase in EV driving range with minimal adverse weight or packaging issues. Secondly, they may be recharged far more quickly than nickel-metal hydride alternatives. The battery pack of a Prius Plug-in Hybrid can be fully recharged in 1.5 hours from a standard, 230V household outlet.

The Prius Plug-in Hybrid's lithium-ion battery pack has about twice the capacity of the third generation Prius' battery, giving the vehicle a maximum speed of 100 km/h when driven in EV mode. With battery fully charged, the Toyota PHV's EV mode range has been increased to approximately 20 km.

The Prius Plug-in Hybrid offers a 30% reduction in combined cycle fuel consumption over the Prius -2.6 l/100 km- and generates CO2 emissions of just 59 g/km.

The first 600 Prius Plug-in Hybrids are already participating in worldwide limited lease projects, with some 200 vehicles distributed throughout Europe. Driving use and charging behaviour will be assessed and analysed, and customer feedback addressed, with a view to verifying the new Toyota plug-in hybrid's overall environmental and technological performance before it goes on sale.

Battery technology

A key element in hybrid technology is its battery the durability and reliability of nickel-metal hydride perfectly suiting Toyota's Hybrid Synergy Drive®, and the superior volume energy density of lithium-ion offering improved EV range and high speed recharging for PHVs.

There is no doubt that battery technology has progressed significantly in the ten years since the introduction of Toyota's full-electric RAV4 EV. Each successive generation of Prius has seen a reduction in battery pack size, weight and cost, yet improved efficiency.

However, challenges still remain. For instance, the cost of lithium-ion batteries needs to be reduced significantly, or a more affordable alternative found.

Fully committed to the most rapid possible advances in battery technology, the company established its own Battery Research Department in June 2008 and has been developing in-house battery technology since the early 1990s.

Toyota's jointly-funded partnership with Panasonic EV Energy (PEVE) has also been a key element of its success in the advancement of hybrid technology. PEVE's three production facilities in Japan will be producing 1.1 million battery packs per annum by September 2010.

Electric Vehicle technology

70% of Europeans currently live in and around cities. And recent Toyota studies in urban commuting patterns in France and the UK reveal that over 80% of car journeys are less than 25 km in length. In France, 55% of journeys are less than 10 km, whilst in the UK that figure rises to approximately 80%.

The demand for short distance commuter vehicles is expected to increase in the coming years and, in this context, the future of electric vehicles in providing short- to mid-term sustainable mobility is assured.

Electricity has high potential as an alternative energy source to oil. It can be supplied easily, and produced from renewable sources such as solar, wind and hydro-electric power.

Toyota has already accumulated an unprecedented depth of knowledge and engineering capability in the field of electric vehicles. Ten years ago, some 1.500 RAV4 EV battery-electric vehicles were either sold or leased over the course of a three year, California-based test programme. Nearly half of these 160 km-driving range, large battery vehicles are still on the road.

However, even with a 160 km range, EVs as a primary mode of transportation do not offer what most customers see as true mobility- and the absence of a comprehensive recharging infrastructure continues to hinder market acceptance of the battery electric concept.

Nonetheless, through further advances in battery technology, and cooperation with governments, related organisations and other companies in charging infrastructure development, Toyota believes these obstacles will be overcome.

To that end, Toyota has continued with the development of short range EVs for commercialisation. At last year's Tokyo Motorshow, the company unveiled its FT-EVII concept, a small commuter EV with a top-speed of 100 km/h and a driving range of over 90 km. Toyota plans to launch a lithium-ion battery equipped EV in the United States in 2012.

Fuel Cell technology

Fuel cell vehicles have the potential not only to solve environmental and energy problems, but also to change the shape and structure of motor vehicles themselves.

Fuel cell car design is liberated from the constraints imposed on conventional vehicles by the need to mechanically transmit energy from the engine to the wheels, creating unprecedented freedom in designing the structure of the car's interior.

Producing electricity through a chemical reaction between hydrogen (stored in the vehicle) and oxygen (from the air), with water vapour the only emission, a fuel cell structure comprises electrodes and polyelectrolyte films sandwiched between separators. When hundreds of cells are stacked together, the result is a fuel cell 'stack', known as an FC stack.

A fuel cell can convert as much as 80% of hydrogen's energy into usable power - about twice the efficiency possible with current generation petrol engines.

Toyota began work on FCHVs in 1992, developing its own hydrogen fuel cells and high-pressure hydrogen storage tanks in house. The company applies its own HSD technology to FCHV development, replacing petrol engines with fuel cells, and petrol fuel compartments with high pressure hydrogen tanks. The Toyota FC stack is a performance leader in fuel cell technology.

The world's first production fuel cell vehicle, the Toyota FCHV, was commercialised in 2002. Toyota's latest fuel cell hybrid, the FCHV-adv -featuring a newly designed, high-performance Toyota FC Stack fuel cell and high pressure tanks- received vehicle-type certification from Japan's Ministry of Land, Infrastructure and Transport on June 3rd 2008.

The Toyota FCHV-adv offers a 25% improvement in fuel efficiency and, through the use of Toyota-developed, 70Mpa high-pressure hydrogen storage tanks, has a single-fill-up cruising range of approximately 830 km -more than twice the cruising range of its predecessor. Furthermore, the Toyota FCHV-adv can operate in —30°C, greatly improving its cold weather performance.

Though a fuel cell vehicle emits no CO2 itself, the CO2 emissions resulting from various hydrogen production methods must be considered for an accurate, well-to-wheel appraisal of FCHV energy efficiency and environmental impact.

Moreover, a smooth shift to a hydrogen-based society will be a significant undertaking. Reaching a consensus on from what to make hydrogen, how to deliver it and how to implement a fuelling infrastructure depends on the combined efforts of all sectors of society, including governments.

To that end -and in anticipation of the imminent commercialisation of a number of FCHVs- Toyota, Ford, Daimler, General Motors, Honda, Hyundai/Kia and Renault/Nissan signed a Letter of Understanding in September 2009 calling for oil and energy companies and government organisations to cooperate in the creation of hydrogen infrastructure networks of sufficient density in Europe, Japan, Korea and the United States by 2015.