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The ever evolving and revolving story of auto engine power sources
Winston Churchill said, “The farther backward you can look, the farther forward you are likely to see.” In the case of automotive power the seeds of the future envisioned by OEM engineers and designers can be found in its history. It is that rich past that has provided most of the inspiration in the search for alternatives to the standard internal combustion engine. The main determining factor in the triumph of gasoline-power over other systems, such as electric and steam was economic and convenience. Cost, range and the frequency of fuel outlets, is as important today as it was 100 years ago. No matter how environmentally friendly a fuel and the system it drives, the ability to keep a vehicle on the road for long distances at an affordable rate is vital.
Although an electric-powered carriage had been invented in 1839 and battery powered-cars, first built in 1842, were a commercial success by the 1890s, the low price of oil became the determining factor in the decline of the electric vehicle as ICE vehicles became more affordable to an ever-larger proportion of the population. So, with the exception of the years of World War II when gasoline was scarce, the market for electric vehicles or hybrids (1920-1960s) was virtually non-existent. However, concerns about air pollution prompted a revival of interest in alternative fuels. In November 1974 an MIT Energy Laboratory Report, The Role for Federal R&D on Alternative Power Systems, was published. The alternatives to the ICE that were under consideration, which included external combustion engines were: diesel engines (including lightweight diesel), Wankel spark-ignition engines, stratified charge engines, gas turbine engines, Ranklin cycle engines, Stirling cycle engines, battery powered electric systems and heat engine hybrid systems. At that time there was scepticism as to whether fuel cell technology had a future in automotive application: "A third less important, area which has been considered as part of an electric drive system is the fuel cell. A fuel cell would convert the chemical energy of on-board fuels directly to electricity, much like a continuously replenishing battery. However, while fuel cell technology continues to be developed for space and several other uses, due to a number of formidable problems there are no programs to apply it to motor vehicles."
Environmentally and financially a reduction in the use of limited resources is the key to the future of transportation. If we can adapt a fuel to slow its rate of burn while increasing its energy release we may have a runner – literally. Rare-earths, hydrogen and biofuels each have their well-known drawbacks. Attempts to extract usable hydrogen from water have so far had no success, though the thought of an exhaust of pure oxygen is very appealing. It would be wonderful if we could extract hydrogen from H20 through electrolysis to power our motor vehicles, but the jury is still out on whether this will ever be possible in spite of many claims to the contrary.
Microbial fuel cells have been explored as a potential power source for automobiles. Once discounted, research is moving on. For example, Penn State University researchers recently developed a new graphite anode for use in MFCs that more than doubles their power output.
Furthermore, it is claimed that electrically charged bacteria fed on waste-water and vinegar could produce a clean hydrogen fuel for automobiles.
The money, however, appears to (literally) be on plug-in hybrids and fuel cells. That is where the investment is going. Building on and running alongside conventional propulsion rather than completely replacing it, appears to be the message from industry. So, are major players actually rather conservative in their approach to the future of the automobile..?
Richard Seymour from Toyota says his company does not have all of its eggs in one basket when it comes to green technologies and is looking into various sources of transport propulsion, “However, at the present time we see for the near- to mid-term future that our full hybrid technology and plug-in technology is the most viable answer.” The range restrictions of pure EVs mean that the company does not currently believe they are ‘the answer’ except for short journey inner-city applications. Instead, emphasis is on manufacturing hybrid versions of all its models by 2020, and a fuel cell vehicle, which it intends to bring to market in 2015. “The step from hybrid to fuel cell will be straight forward,” says Seymour, “as the vehicles will just require removal of the internal combustion engine and replacement with a fuel cell stack (the motor etc will already be in place). Toyota’s strategy includes constantly improving and downsizing its hybrid technology to make it even more efficient.
In December 2011, Toyota signed a memorandum with BMW concerning mid-to-long-term collaboration on next generation environmentally friendly technologies, including joint research related to next-generation lithium-ion battery technology for use in hybrid, plug-in hybrid and all-electric vehicles, and on June 29, 2012, it was announced that the two companies were extending their partnership and had agreed to explore possible collaborations in fuel cell system technologies, sports cars, electrification and lightweight technology.
Seymour is confident about the company’s development of modern battery technology: “Hybrid battery production has increased to an annual capacity of 1.1 million units.” He says Toyota will continue to invest in both Ni-MH and Li-ion batteries because they suit different needs: “The durability and reliability of nickel- metal hydride batteries perfectly suits Toyota’s hybrid vehicles and the superior volume energy density of lithium-ion batteries offers improved EV driving range and high-speed recharging for plug-in and electric only vehicles. However, the cost of lithium-ion batteries needs to be reduced significantly or a more affordable alternative found.”
Toyota has its own battery research division at the Higashi-Fuji Technical Centre, where in January 2010 a battery engineering development division was established, bringing the number of engineers dedicated to battery development to over one hundred. The company is now in a joint-venture partnership with Primearth EV energy whose facilities are capable of producing 1.1 million battery packs per annum.
Bosch began its research into all-electric drives in the 1960s with prototypes fitted from 1967, and by 1974 the company was involved in large-scale trials with electric buses. Research into recuperation began in 1966 and was applied in a trial involving diesel/electric hybrid buses in 1979.
However, the belief at Bosch is that, ‘Internal combustion engines will continue to be the dominant automobile drive system for the next 20 years.’ The company is therefore committed to boosting the energy efficiency of the drivetrain and cutting CO2 emissions by ‘unlocking’ the potential of traditional drive technologies in the short term as a response to emissions legislation in Europe, America and Asia. Bosch confidently expects to reduce the consumption of gasoline and diesel engines by a further third.
The company is building systems compatible with a number of different low-emission fuels. These fuels include gasoline with high ethanol content, pure ethanol (E100), Compressed natural gas (CNG), and biodiesel derived from vegetable sources. The company is already designing injection systems with biofuels in mind and its FlexFuel engine management system enables engines to run on any mix of Gasoline and ethanol. Furthermore, the use of natural gas as a power source is something about which Bosch is also very enthusiastic.
New technology, however innovative, efficient and desirable will be confined to prototype unless the price is right. Lower costs are regarded key ‘if hybrid technology is to penetrate the market successfully’. As a consequence all of the company’s hybrid systems have a modular structure so they can be used in the vehicles of different manufacturers. Bosch regards hybrid is “transitional technology” on the way to the all-electric drive, which is dependent on battery technology and renewable sources. “At present,” the company says pessimistically, “the costs still far outweigh the benefits.”
Pamela Fletcher, chief engineer at GM responsible for the Chevrolet Volt concurs with industry thinking when it comes to market expectations: “We expect conventional powertrains with internal combustion engines will have a long future – however, a lot of them will be supported by various levels of electrification.
“We anticipate that vehicle electrification will increase in the future. Battery-electric vehicles will become competitive for some applications, especially urban, short-distance driving. Extended range electric vehicles, like the Volt, provide longer driving range and offer full capability without range anxiety.”
She tells ETi, “The making of the Chevrolet Volt is a project that turned the idea of an electric vehicle with extended range (EREV) into a reality.” Although as she says the Volt continues to be a breakthrough vehicle, she admits that there are important hurdles ahead: “For the next generation our most critical need is to focus on cost reduction opportunities for electrification components, like the battery. This will be critical to being able to expand market penetration of profitable electric vehicles.”
When we ask about her vision of the future of alternative powertrain systems, Fletcher predicts, “Biofuel does provide customers with choices in advanced propulsion technology and CNG [compressed natural gas] is a clean-burning and domestically produced fuel. Hydrogen powered fuel cell electric powertrains do have potential and through generational learning cycles cost will come down, but ultimately deployment will be determined by hydrogen fuelling infrastructure growth.”
She continues, “As part of our development we evaluate all chemistries, including lithium-ion. This also includes materials and energy storage technologies that go beyond current lithium ion. Future vehicle needs and the appropriate advancement of these technologies will help us determine the appropriate window of new technology insertion as we plan new electric vehicles.”
Dr Christian Mohrdieck Director Fuel Cell & Battery Drive Development at Daimler AG says, “The future definitely lies in the electrification of the drivetrain. But the experts at Daimler are not expecting one single technology as a silver bullet for sustainable mobility, but are setting out to provide tailor-made solutions to suit all customer requirements. The company is employing an intelligent mix of innovative combustion engines, hybrid drives and zero-emission electric vehicles powered by battery or fuel cells.” He says Daimler is committed to the use of clean and alternative fuels: “On our way to zero-emission mobility, fuel cell technology in particular and the potential of hydrogen as energy source for the future will play a central role.”
Professor Thomas Weber, responsible for Mercedes-Benz Cars Group Research and Development, says that car manufacturers (in particular), energy providers and the petroleum industry should make a maximum contribution: “Such a technological change – from the conventional internal combustion engine toward emission-free mobility in the long term – cannot be implemented by the individual."
Lotus Engineering’s solution is to build a family of purpose-built three-cylinder (aiming at twin-cylinder) gasoline engines as range extenders for installation into vehicles as “components” built in large numbers and distributed to OEMs across the world. To this end the company has entered into cooperation with Spanish company Fagor Ederlan to achieve sufficient large-scale manufacture.
Engine expert, Jean-Pierre Pirault doesn’t expect any “bolts from the blue” or “physics beaters” in the medium term: “It’s more a case of progressive development to meet the prevailing emissions and CO2 legislation, whilst providing fun to drive and increasing refinement.”
However, he believes the fuel cell may appear before 2030 in some small city Ecars: “It would be exciting to imagine all those other developments, such as Bottoming cycles, might happen, but this is only likely in heavy duty and marine powertrain applications.”
“Whilst there is a huge future potential for light duty vehicles with China, India, south America coming on stream, the real problems will be with gridlock rather than energy efficiency and emissions, which are relatively easy to solve.”
There is much enthusiasm in the industry for the potential of fuel-cell technology, which, it is hoped will be shared by the car-buying public in time. The costs of hydrogen fuel cell systems and storage, which stifled early development, have steadily reduced in the last 10 years, leading to optimism that production of fuel cell vehicles, as compared with conventional and hybrid vehicles could become competitively attractive in the near future. While sufficient storage is a problem there are alternative methods being explored such as gas, liquid and materials. Durability is also an important factor. While considerable improvements have been made, further increases in durability are considered necessary. Fuel delivery is a particular concern to both manufacturers and consumers given that existing gasoline infrastructure and delivery methods are incompatible with the outlet of hydrogen.
Could a leftfield innovation representing a practicable solution to the automotive needs of the twenty-first century suddenly render all the millions of dollars worth of investment into lithium-ion battery, hybrid and range-extending technology worthless..? Unlikely; a global market that is only just coming round to accepting the viability of well-known types of alternative or modified powertrains is hardly likely to go electro-magnetic, anti-gravity or even steam-electric hybrid in even the medium to long term. Even the latest hybrids and plug-ins are unlikely to proliferate at a rate that unduly concerns the retailers of standard gasoline or diesel vehicles. Cost will continue to be the determining factor however desirable the new technology. Most experts predict the growth of alternative systems and fuels will be slow, but nevertheless sure, and the conservative nature of the average driver and their priorities will ensure that the car of tomorrow will resemble and grow out of the automobile of today and indeed yesterday.
14 December 2012