Watt is the future

by 19 Dec 2008


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There’s strong evidence to show that cars, not so different from those we drive now, can continue and even expand their traditional role in providing us with personal transport in future decades – provided we can reduce their CO2 emissions dramatically, from today’s 120g/km-plus to about 40g/km by 2050.

Broadly speaking, that means we’ll need to reduce CO2 emissions of the fleet of new cars by about two percent a year over the next 40 years. And so far, the world’s car manufacturers are inventing the technologies that will allow us to do this, while also continuously improving safety, comfort, convenience and feature levels, and simultaneously keeping style, performance and the driving experience interesting for customers. But what will these new low-emissions cars be like?

Building efficiency

First, some fundamentals. There are only a few ways of improving CO2 emissions, and they depend on two things: improving the efficiency of the vehicle or reducing the carbon-intensity of the fuel.

Vehicle efficiency improvements flow quite directly from waste elimination or reduction measures, and the great thing about this is that there is no consequent reduction in other functions.

Performance, for instance, is likely to increase, not decline, if you improve efficiency. Here are some ways to make gains: Reducing friction in aerodynamics, cutting engine pumping losses through wider-ratio multi-speed gearing, and using lower-friction components in wheel/tyre rotating assemblies, the driveline and powertrain rotating assemblies.

Avoiding or reducing use of energy when it is not needed, through the use of smart alternators that only charge the battery when decelerating, deceleration fuel shut-off, reduced idle speeds, stop-start systems, electric power steering, electric pumps instead of belt-driven engine pumps.

Recapturing energy, such as heat, which is normally expelled as warm air or warm exhaust gas, by using turbocharged engines that allow use of a smaller base unit for the same power, smart cooling systems, regenerative braking, hybridisation.

Lowering weight to allow smaller engine displacements and architectures, with secondary benefits such as smaller catalysts, radiators, brakes and crash structure.

These vehicle and power-train efficiencies alone are probably capable of getting us down to 80g/km, with rising cost implications, but they will not get us to the ultimate target of 40g/km.

To achieve that, we will need to switch from relying on fossil fuels to a mixture of liquid biofuels and electricity (generated from an increasing mix of non-fossil sources). The cheapest efficiency measures are naturally likely to be adopted first.

Scaling out the technology

Most, if not all, new efficiency-building technologies will start at lower volumes, either as variants of best-selling model ranges (such as Volkswagen’s BlueMotion models) or on premium-branded vehicles such as Mercedes-Benz or Lexus.

Experience gathered with these cars will allow engineers to make these technologies much more affordable to ordinary consumers. This, in turn, will fuel demand and lead to the next phase of cost reduction – scale economies – which should allow the technology to be practically standardised, except for the cheapest entry-level models.

This process of increasing scalability is vital for addressing the CO2 challenge because it is the sheer scale of car usage, driven by popularity and affordability, which is causing the problem in the first place.

Technology adoption will probably take place in rough descending order of cost-effectiveness, so solutions such as low-resistance tyres (which are relatively inexpensive but very effective) will find their way onto cars before wholesale stop-start systems, which are great for city delivery driving cycles but quite expensive and less effective.

The next generation

So what about cars for the near future? The biggest change I see in car design over the next 10 years is not the mass adoption of hybrids or electric cars, but the growth of a new breed of petrol engine. It will have: A much smaller displacement. 1) Fewer cylinders to reflect that smaller displacement. 2) Direct fuel injection. 3) A high compression ratio. 4) Variable valve timing and lift. 5)An ability to burn a blend of petrol and bioethanol. 6)Sophisticated turbocharging. 7)Electric water and oil pumps, air-con compressors and electric power steering. 8)Fast warm-up devices.

Today’s typical 1.8-litre four-cylinder engine in a mid-sized family car in Europe will morph into a 1.2-litre three-cylinder turbo engine with even better performance yet up to 20 percent lower CO2 emissions and correspondingly better fuel economy.

It will be more expensive than today’s petrol models, but not much different from today’s diesels, which account for 50 percent of sales in Europe and are much cheaper than hybrid electric vehicles.

The electric pumps and motors that support these new engines will be microprocessor-controlled to provide only the power needed, but they will offer other functions like parking assist, a by-product of electric power steering.

The new engines will be mated to seven and eight-speed automated twin-clutch gearboxes that offer wide ratio ranges and automatic selection to ensure that they operate in their efficiency sweet spots.

Because this bundle of technology is relatively affordable (the price hike will probably be similar to that involved in choosing a high-performance engine over an entry-level version), it promises to become common in top-selling models soon.

That makes 100g/km for a Focus-sized car realistic, with 90g/km achievable with a stop-start system, a smart alternator and vehicle friction improvements, and 80g/km possible with the development of stratified charge combustion systems and perhaps throttle-less petrol engines running without spark ignition.

Smaller engines will be even more practical if car makers can end the inexorable increases in weight of the past three decades. Historically, improvements in weight efficiency due to new design technology, better manufacturing processes and materials have been more than counterbalanced by a need to add weight to improve safety, cut emissions and provide the extra features demanded by customers.

This has led to increases in engine size to maintain vehicle performance, but I expect to see this trend end quite soon.

Electrification

Beyond 2020, cars in the Focus class (which in India is equivalent to the Honda Civic) will need to proceed from 90g/km to around 40g/km by adopting more expensive hybrid solutions and moving away from exclusive dependency on fossil fuel.

Today’s ‘parallel’ hybrids, such as the Toyota Prius, use both electric motors and internal combustion engines, working in parallel, to supply torque to the wheels. In future ‘series’ hybrids, the only motor driving the wheels will be electric; the internal combustion engine will only drive a generator to supply the battery, which in turn powers the electric traction motor.

These hybrids, like today’s cars, have a very limited range when they rely solely on electric power only.

In my view, electricity will become very important in partially replacing fossil fuels. It will be used in ‘pure’ small electric cars with limited range in large cities, and also in ‘plug-in’ hybrids.

These have a range of 40-60 kilometres, much larger than today’s hybrids, allowing electricity to be used for urban and shorter rural journeys while preserving the massive range of today’s normal car by using an engine to recharge the battery when required. Such vehicles are hugely expensive at present, but they represent the best hope for larger, all-purpose vehicles of meeting CO2 emissions targets.

Under-utilised capacity

In spite of a huge diversity of body styles, today’s cars are essentially ubiquitous. Each can go to the supermarket for a litre of milk or drive from Mumbai to Delhi. Each has deliberately designed-in redundancy for much of its usage, in case it has to be used for a completely different mission.

This is what consumers want – spontaneous flexibility – but in the next 20 years we may see a gradual fragmentation of powertrain and fuel types, as one size no longer fits all. Look out for: Electric city cars (proper cars, not runabouts like the G-Wiz) in urban areas, probably leased by the hour or month.

Plug-in hybrids as family cars for the affluent. Super-efficient internal combustion cars for the less affluent (who may rent a larger model for longer trips). Mild hybrid diesels for regular long-distance drivers.

This diversification is unlikely to happen until after 2020, because consumers will be reluctant to restrict their cars’ flexibility. Yet I believe it will be an essential factor on our journey from 90g/km to 40g/km.

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