| Understanding the buzzwords of alternative | | | | hatchback, and is due to go on sale before the |
| powertrains and fuels can be hard. Especially when | | | | end of the year in a number of countries - |
| the language used by equipment and vehicle | | | | certainly Japan and the U.S., and possibly |
| manufacturers, keen to talk up their exciting new | | | | elsewhere. The Leaf will be available in Europe by |
| technologies, is sometimes light on reality. We | | | | 2012, probably sooner. It is completely electric, |
| hope that, when you emerge from reading this | | | | with a Li-ion battery pack, a maximum speed of |
| page, you will be able to face the subject head-on | | | | around 90mph and a range of roughly 100 miles. |
| without being distracted by, dare we say it, hot | | | | And Peugeot's little Ion, just 3.48m long, will be |
| air. | | | | available to rent by the end of the year. The Ion |
| A significant problem with talking about alternative | | | | uses a Li-ion battery pack that takes six hours to |
| fuels is that it's usually impossible to make genuine | | | | recharge, or 30 minutes to 80 per cent. capacity. |
| comparisons between the effectiveness of | | | | Motor outputs are 64PS and 180Nm, and a |
| different technologies. And that, of course, is | | | | maximum speed of 130km/h (81mph) is quoted. |
| what everyone wants to do. Reliable data are just | | | | A hybrid is a vehicle with more than one source |
| not available to compare - for example - the | | | | of power. In practice, this mean an internal |
| overall carbon efficiency of one fuel against | | | | combustion engine plus an electric motor. |
| another, from the oil well (or sugar cane) to the | | | | This tandem arrangement raises various |
| wheel. How much energy is required to produce a | | | | possibilities. Most obviously, the combustion engine |
| particular type of fuel? Can that energy be | | | | can provide the vehicle with a 'normal' on-road |
| generated using renewables? How hard is it to | | | | performance and range for long-distance driving |
| store and transport the fuel? There are too many | | | | on fast roads. On the other hand, running the |
| variables. So we hope you will understand that, in | | | | electric motor by itself will deliver zero local |
| not providing you with a neatly packaged and | | | | emissions in town, while regenerative braking helps |
| presented clear-cut answer to the world's big | | | | to extend battery life, especially in stop-start |
| transport questions, we're not being indecisive. | | | | traffic. Inevitably, though, the range under electric |
| Our intention is that you will be able to read | | | | power will be limited: the weight and bulk of such |
| future articles about alternative fuels with enough | | | | a complex drivetrain means that there is a lot of |
| insight to fish the few morsels of solid information | | | | mass to accelerate and little spare room for an |
| out of the PR chaff. | | | | especially large battery pack. |
| This page, then, is an introduction to alternative | | | | There is a third mode of operation that makes |
| fuels and drivetrains, and to how they work in | | | | hybrids interesting in some situations. The electric |
| practice. It's not an engineer's monograph - not | | | | motors in automotive use often produce quite |
| least because the technologies used in alternative | | | | modest power, but they invariably generate |
| drivetrains are developing very quickly, and there's | | | | considerable torque. And electric motors produce |
| a lot of recently-patented equipment out there | | | | their maximum torque as soon as they start to |
| which the press are not cordially invited to | | | | rotate. So if you use the combustion engine and |
| dismantle. | | | | the electric motor, you can get quite a shove in |
| Although the technologies of alternative | | | | the back. This is the basis for a breed of car |
| powertrains are moving and evolving rapidly, it will | | | | known as the 'mild hybrid', in which environmental |
| be many years yet before we see a major shift | | | | protection is a thin disguise for spectacular |
| in the types of cars that buyers actually drive | | | | electrically-boosted acceleration. BMW's Active |
| home from the showroom. The reasons are | | | | Hybrid 7 is an archetype: it uses a turbocharged |
| simple. The new technologies that already work - | | | | 4.4-litre V8 petrol engine with a three-phase |
| hybrids, for example - are complex and | | | | synchronous electric motor, developing an overall |
| expensive, while the more radical developments | | | | system output of 465PS and maximum torque of |
| are still at the prototype stage. Where is your | | | | 700Nm. Acceleration, as you might imagine, is |
| local hydrogen filling-station, or the nearest | | | | extraordinary. |
| charging point for your electric car? There are | | | | As we write, the BMW's thunder has been stolen |
| some around, but it will be a while before we can | | | | by Mercedes-Benz, whose F800 research vehicle, |
| tour the country in a car powered by electricity | | | | which uses a 3.5-litre V6 petrol engine as its main |
| or hydrogen. | | | | powerplant, can incorporate either a hydrogen fuel |
| Last autumn, Volkswagen published a document | | | | cell system or a plug-in facility for its lithium-ion |
| called Update on the Future: Technologies on the | | | | battery. Not both, sadly. |
| roadmap to the world of tomorrow. Its authors | | | | Series and parallel |
| are in no doubt about the pace of change. 'Bold | | | | A hybrid vehicle can be a series hybrid, or a |
| promises are being made which suggest that | | | | parallel hybrid, or even both. A Toyota Prius, for |
| future technologies - especially electric cars - are | | | | example, is both. 'Series' and 'parallel' refer to how |
| already production-mature for the mass market | | | | the two power units - the combustion engine and |
| today. That is incorrect. Because the path to the | | | | the electric motor - work together. |
| emissions-free car is a long one. Consequently, the | | | | If your car can be powered by its combustion |
| Volkswagen Group is following a Powertrain and | | | | engine or its electric motor but not both, it is a |
| Fuel Strategy that is laid out for the long term | | | | parallel hybrid. If the car is always powered by |
| yet will still culminate in the reinvention of the | | | | electricity, but there's a combustion engine on |
| automobile.' | | | | hand to act as a generator, it's a series hybrid. |
| There are two phrases here that stand out. 'Long | | | | Vauxhall's radical Flextreme GT/E Concept, on |
| term.' And, 'Reinvention of the automobile.' | | | | show at Geneva, is a series hybrid. If you can |
| But maybe Volkswagen is being cautious. In | | | | deploy either or both, then it's a series and parallel |
| November, Guillaume Faury, Executive Vice | | | | hybrid. |
| President, Manufacturing and Components at | | | | While General Motors has shown some |
| Peugeot-Citroën, announced that the Group | | | | commitment to series hybrids, to the extent that |
| would be devoting more than half of its R&D | | | | the Company will be putting a series hybrid model |
| expenditure for the 2010-2012 period to new | | | | called Ampera on sale next year, it is likely that |
| technologies aimed at cutting carbon dioxide and | | | | the greater flexibility of series-parallel systems will |
| other emissions. | | | | prevail. |
| The pursuit of new powertrains is serious | | | | There have been a lot of very promising cars |
| business. | | | | with this type of powertrain that have failed to |
| What are the alternatives? | | | | make it into the showrooms, chiefly for |
| The most familiar type of alternative fuel vehicle | | | | marketing and cost reasons rather than any |
| is the hybrid. In fact, this is actually not a single | | | | significant technical issues. PSA alone has produced |
| technology at all, but a general term for a vehicle | | | | four in recent years: Peugeot's 307, 308 and |
| that uses more than one form of motive power. | | | | 3008, and Citroën's C4 HDi Hybride. Then there |
| The best-known hybrid vehicle Toyota's Prius, | | | | is Volkswagen's Golf TDI Hybrid. PSA's '5 by |
| which uses a petrol engine and an electric motor. | | | | Peugeot' show car at Geneva is an impressive |
| Confusingly (and incorrectly), Toyota uses the | | | | reminder that the Company will have something |
| word 'hybrid' to describe its fuel cell car, which is | | | | to sell us soon. When PSA and Volkswagen decide |
| actually not a hybrid at all because it has only one | | | | to push ahead with marketing cars with hybrid |
| source of power. A fuel cell vehicle uses (usually) | | | | powertrains, Toyota's Prius is going to have a real |
| hydrogen gas as a fuel, producing electricity to | | | | brawl on its hands. At the moment it looks as |
| drive a traction motor. | | | | though the Prius's first competitor won't appear |
| We are all familiar with traditional electric vehicles | | | | until early 2011, when Peugeot intends to launch |
| that run on battery power alone, recharged at | | | | its interesting all-wheel drive 3008 Hybrid 4. |
| charging stations or from the domestic supply. | | | | Conventionally, all of the power for a hybrid |
| They have a long history - as have | | | | vehicle comes from the combustion engine. This is |
| straightforward piston engines fed on | | | | critical. Some of the engine's power is converted |
| non-hydrocarbon fuels. In the 1970s, the Brazilians | | | | to electrical energy, stored, then deployed by the |
| began running Fiat 147s on ethanol produced from | | | | electric motor when needed. In a conventional |
| the sugar cane that grows easily in that country, | | | | vehicle, of course, engine power is directed |
| and ethanol is a major fuel for cars and light | | | | straight to the road, give or take what goes into |
| commercials in Brazil today. In Europe, hydrogen is | | | | keeping the 12V battery charged. Each conversion |
| also seen as a fuel to watch for combustion | | | | from one type of energy to another represents |
| engines. | | | | a loss of oil-well-to-wheel efficiency, while the |
| Ethanol is not the only bio-fuel. We have all heard | | | | substantial mass of the on-board systems makes |
| about biodiesel, originally produced from rapeseed | | | | the car heavier than its conventional competitors. |
| oil. Although seed oils are not now seen as a | | | | The only gain compared with a conventional car is |
| useful way forward for making fuel, there are | | | | the regenerative braking system. |
| new production systems for biodiesel that are | | | | Plugging in |
| attracting interest. Given that diesel engines are | | | | A new type of hybrid is gaining ground: the plug-in. |
| thermodynamically efficient, and non-fossil fuels | | | | It's not radically different from any other hybrid, |
| have the potential to be produced to a high | | | | but it has the facility to allow the driver to |
| degree of purity, this type of fuel certainly has a | | | | recharge the battery pack from an an exterior |
| future. | | | | supply. Coupled with a larger-capacity battery, it |
| Biofuels: ethanol & biodiesel | | | | gives the plug-in hybrid a better electric range and |
| Most of the engine designs that we are already | | | | more flexibility. The basic powertrain technology is |
| using can be modified to run on biofuels. Bioiesel | | | | the same as other hybrids. Volkswagen is set to |
| can be made successfully from biomass - | | | | unleash a fleet of plug-in Golf hybrids - using a |
| mulched or chipped plant material - while | | | | powertrain called Twin Drive - onto the streets of |
| anhydrous ethanol produced from sugarcane can | | | | Berlin, while Toyota has a plug-in version of its |
| be mixed with petrol. In Brazil, all fuel for | | | | Prius that's due to start road trials in mid-2010. |
| petrol-engined vehicles must be at least 22 per | | | | To date, Toyota has been pre-eminent in selling |
| cent. ethanol. | | | | hybrids. But the company has made it clear that |
| Earlier this year, the U.S. Environmental Protection | | | | it's just not interested in using diesel engines, a |
| Agency designated Brazilian sugarcane ethanol as | | | | decision that represents a loss of 20-25 per cent. |
| an 'advanced biofuel' due to its 61 per cent. | | | | in fuel efficiency - more than the Prius's |
| reduction of total life cycle greenhouse gas | | | | regenerative braking could ever recoup. PSA and |
| emissions. This is good, of course, but when the | | | | Volkswagen are true believers in the efficiency of |
| alcohol is mixed with ordinary petrol, the | | | | diesel engines, but their hybrids aren't for sale - |
| advantages tend to be diluted. Specifically, ethanol | | | | yet. |
| has a lower energy density than petrol, so even a | | | | And as this is written, Jaguar Land-Rover is |
| vehicle running on a blend of 85 per cent. ethanol | | | | advertising for engineers with experience of |
| with petrol - known as E85 - will produce only | | | | hybrid engine technology. |
| marginally less carbon dioxide than it does with | | | | Hydrogen fuel cells |
| raw petrol, because it will be considerably thirstier | | | | A fuel cell vehicle uses (usually) hydrogen gas as a |
| overall. This is not the end of the world, though, | | | | fuel, together with with oxygen from the air, to |
| because spark-ignition engines can be designed to | | | | generate electricity. This then powers the vehicle. |
| run on pure hydrated ethanol, or E100. The | | | | The majority of automotive manufacturers plan |
| Brazilians have been doing it for 30 years. | | | | to start the commercial mass marketing of |
| Biodiesel can also be blended easily with mineral | | | | vehicles powered by hydrogen fuel-cells within the |
| fuel. There are some potential pitfalls that need to | | | | next five to ten years. |
| be answered with recognised standards - for | | | | The environmental concerns with this technology |
| example, the lubricity of the fuel needs to be | | | | are not about the direct emissions from the |
| adequate to prevent the engine's fuel injectors | | | | vehicle, but with the methods used to produce |
| destroying themselves. Similarly, the purity of | | | | the hydrogen fuel. |
| biofuels needs to be subject to mandatory | | | | Hydrogen is the simplest and lightest of the |
| standards. | | | | chemical elements. It freezes at -259°C and boils |
| If we can produce bio-mineral blends that | | | | at -253°C. In a fuel cell, hydrogen gas - supplied |
| conform to the same performance and quality | | | | from an on-board tank - and oxygen from the air |
| standards as current fuels, they can be offered | | | | are forced into contact with each through a |
| as direct substitutes using existing infrastructure. | | | | polymer membrane. They combine to form |
| The need to develop new infrastructure will slow | | | | water, a fuel cell vehicle's only direct emission. The |
| down the introduction of any novel fuel, even if | | | | process of combining hydrogen gas H2 with |
| the public is keen to buy a car that runs on it. | | | | oxygen gas O2 produces (apart from water) |
| Care needs to be taken in auditing whole-cycle | | | | electrical energy and heat. This electrical energy is |
| carbon dioxide for any new biofuel plant or | | | | fed to the vehicle's drive motor. |
| process, because an advantage over mineral fuels | | | | A single hydrogen cell produces less than one volt, |
| is not guaranteed. It can be substantial, but it can | | | | so several hundred cells are connected in series to |
| be nothing - or worse. According to Volkswagen, | | | | form a 'stack' which can generate enough power |
| 'Depending upon the raw material and process, | | | | to drive the vehicle. |
| the carbon dioxide benefits can fluctuate wildly, | | | | In Nissan's experimental fuel cell vehicle, the car's |
| even with the same product - in the case of | | | | battery is used as an auxiliary power source to |
| ethanol, between 0 and 90 per cent.' | | | | supplement the fuel cell stack's output under |
| And as the environmental lobby has pointed out, | | | | acceleration. The battery pack also provides |
| there is a danger that the pressures placed on | | | | storage for energy captured by the brake energy |
| land for the production of biofuels could have | | | | regeneration system. |
| serious environmental and social consequences. | | | | Nissan has been running specially modified versions |
| Synthetic hydrocarbon fuels | | | | of its X-Trail powered by hydrogen fuel cells in |
| Making synthetic fuels is a great way to achieve | | | | Japanese cities, Canada and the United States for |
| very high standards of purity, consistency from | | | | the last five years. The car uses a co-axial motor |
| day-to-day, and self-consistency in the range of | | | | delivering 120PS and 280Nm. Nissan's stated aim is |
| carbon chain lengths in the fuel. Like purity, | | | | to have a fuel-cell vehicle in full production and on |
| chain-length influences the quality and consistency | | | | sale in North America and Japan during the first |
| of combustion. This means cleaner local emissions, | | | | half of the next decade, with sales in Europe |
| better power and better fuel economy. | | | | following shortly afterwards. The current version |
| Synthesising fuels also opens up the possibility of | | | | of the vehicle has a maximum speed of 150km/h |
| designing new types of combusion engine, using | | | | (93mph) and an operating range of more than |
| tailored fuels that don't fit into our existing | | | | 300 miles. |
| categories. This is particularly significant because | | | | As is the case with other alternative powertrains, |
| of the increasingly blurred dictinction between | | | | you can't buy a fuel cell car, but dvelopment work |
| diesel and petrol engines. The adoption of direct | | | | is dependent on companies and institutions leasing |
| fuelling for engines running on petrol means that | | | | the vehicles for day-to-day use. The first of |
| these engines are no longer carburated: fuel is | | | | Nissan's X-Trail FCVs to find its way into the |
| injected at the point where combustion is required | | | | hands of a lease customer was handed over on |
| to start, just like a diesel. Combustion is triggered | | | | 14 January to a soft drinks company in |
| by a combination of a spark and the temperature | | | | Sacramento, California. |
| and pressure conditions in the combustion | | | | Toyota's current fuel cell vehicle is the FCHV-adv, |
| chamber - not just the latter, as is the case with | | | | announced in 2008. Like the Nissan, it's an MPV. Its |
| a diesel engine, but it's worth bearing in mind that | | | | hydrogen tanks have the same operating |
| conventional petrol is blended specifically to resist | | | | pressure (70MPa) as the Nissan's, giving the car |
| compression ignition. | | | | an operating range of roughly 500 miles. |
| Traditionally, synthetic hydrocarbons have been | | | | Storing hydrogen |
| made from natural gas. Clearly this gives no | | | | Storing enough hydrogen onboard a vehicle to |
| carbon dioxide advantage over ordinary fuels, but | | | | provide a reasonable driving range has been one |
| biomass can easily be used as a raw material to | | | | of the key problems with these vehicles. While |
| produce the feedstock for synthetic fuel | | | | hydrogen is a highly efficient fuel with excellent |
| production. | | | | energy density by mass, it has poor energy |
| Plug-in electric vehicles | | | | density by volume, meaning that it requires a |
| The single major potential drawback of a plug-in | | | | larger tank than a petrol or diesel vehicle to store |
| electric vehicle is that the electricity you feed it | | | | the same amount of energy. |
| could well be generated using fossil fuels. That | | | | The solution is to store the hydrogen under high |
| being the case, it is far more efficient to run a | | | | pressure. Early experimental FCVs used a tank |
| small diesel engine - perhaps as part of a hybrid | | | | pressure of 35MPa, but storage systems have |
| powertrain - and convert the chemical energy in | | | | now improved, allowing the gas to be stored at |
| the fuel directly into motion. But of course, there's | | | | 70MPa. Doubling the pressure allows about 30 per |
| always the potential to generate electricity using | | | | cent. more hydrogen by mass to be stored in the |
| renewables, and that's why plug-in technology is | | | | same size tank. |
| important for the future. | | | | Nissan's current 70MPa tank has an inner |
| Lithium-ion battery technology has worked | | | | aluminium liner and an outer layer of carbon fibre |
| wonders for the range and performance of plug-in | | | | reinforced plastic. The C-FRP layer uses a |
| electric vehicles (and also for the electric range of | | | | high-strength, high elasticity carbon fibre weave |
| hybrids). These batteries have a higher power | | | | with a special winding pattern designed to |
| density than NiMH packs and are less prone to | | | | withstand high pressure. |
| lose efficiency as a result of repeated | | | | One of the key problems associated with |
| part-charging or deep-cycling. | | | | hydrogen fuel cells has traditionally been that they |
| Lithium-ion battery packs have been under | | | | don't like the cold. For the fuel cells to operate, |
| development for cars since the early '90s. The | | | | they must be humid inside: without some water |
| latest versions use manganese anodes and a | | | | about, the electrochemical process can't happen. |
| planar, laminated structure, instead of the more | | | | And then there is the question of the water that's |
| traditional cylindrical design. The laminated form is | | | | generated as a byproduct of the process. If |
| cost-effective as well as giving a long life and | | | | ambient temperatures are low enough to freeze |
| good cooling performance. It also uses fewer | | | | the inside of the cells, then not only is the vehicle |
| components than earlier types. At the same time, | | | | not going to move, but the cells will be irreparably |
| the laminated construction has boosted power by | | | | damaged. It seems that development has largely |
| 150 per cent. while halving the physical size of the | | | | overcome the traditional low temperature |
| complete battery pack. And as if that weren't | | | | operating problems, to the extent that Toyota is |
| enough, the new design is also twice as efficient | | | | now comfortable that its FCHV-adv can start and |
| as a conventional cylindrical Li-Ion battery, even | | | | operate in cold regions at temperatures as low as |
| after five years or 100,000km of continuous | | | | minus 30 degrees Celsius. The company isn't |
| usage. | | | | presently saying anything about how the cell stack |
| Brake energy regeneration systems, which are | | | | is protected from freezing when the vehicle is |
| now universal on vehicles with alternative | | | | parked. |
| powertrains, have also boosted operating range - | | | | According to Nissan's calculations, solutions to the |
| considerably so in town, where the vehicle | | | | technical issues connected with hydrogen fuel cells |
| decelerates (and accelerates) frequently. These | | | | - including durability - should become clear 'by |
| systems are also making an appearance in | | | | 2010', while drastic cost reductions and a further |
| conventional cars - BMWs, for example. | | | | breakthrough in hydrogen storage systems by |
| Later this year, Nissan will start production of a | | | | 2015 will make fuel cell vehicles marketable. |
| new car called Leaf. It is a conventional five-door | | | | |