Gasoline engines in most vehicle only convert about 30% of the potential chemical energy into motion, the remainder exits the drive-train as waste heat. 40 MPG + can be achieved using clean technology innovations!
Thermodynamics play a pivotal role in modern vehicle design as the metal engines utilized for power can only operate somewhat efficiently in a narrow elevated temperature band between 150-230 deg F due to the metal alloys utilized in the engines construction (aluminum). Water cooling with an air exchange radiator system dominates thermal management of engines, while a heater core is often utilized to translate some of the engines waste heat into the cabins for occupant HVAC uses, namely heating in the winter.
Cheap Thermocouple Energy Capture
New techniques to harvest electrical energy from the exhaust are making use of novel low cost thermocouple capture technology after decades of niche uses cases in low volume space probe/ aerospace applications. An estimated 2-3% net system efficiency improvement thereby noted as an example of how hard it can be to eek more energy out of a system than is fundamentally flawed. While piston internal combustion engines are well proven, they are not the most intelligent way to produce propulsive energy in a wheeled vehicle. The innovations are being developed as a partnership between DRL, a German automotive R&D firm and Yamaha of Japan, the conglomerate that builds musical instruments and sport bikes. Yamaha also tuned the exhaust and intake system of the Lexus LFA to produce motor enthusiast acoustical bliss! Long ago turbo-chargers were utilized to improve engine output and thermal efficiency, a resurgent application noteworthy in the Ford Eco-Boost Engines. Analytical forecasting research indicates that engine downsizing with turbo-charging and direct injection will be part of many future generations of gasoline powered vehicles.
Capturing energy from the hot pressurized exhaust gases of an engine exists in well developed turbo-charging technologies where the hot pressurized exhaust spins a turbine on the same shaft as an air compressor that forces compressed air fuel charges into the intake. Turbo-charging allows smaller displacement engines to produce more power with increased thermal efficiency, but the increased mechanical and thermal complexity necessitates solutions that increase capital costs of turbo-charged engines. Increased thermal loading of turbo engines also reduces reliability while giving rise to elevated exhaust temperatures that contribute to the formation of additional air pollutants in the exhaust stream.
Tail Pipe Problems
Tail pipe exhaust is a complex mixture of pollutants that exit in variable way depending on drive pedal input, topography of the driving route, vehicle mass, vehicle age, emission controls technologies employed, and other variables like intake gas chemistry in traffic corridors and outside temperatures. Looking at tailpipe exhausts from an overview level provides a clearer image. NOX's (oxides of nitrogen) foul brown lung irritating gases. Carbon Soot ( Particulate Matter : PM ) penetrates deep into lung tissue; toxic. Carcinogenic Vapors like Benzene & Toluene that cause Cancer + Liver & Kidney Damage. Unburned gasoline associated with cold engine warmup, rich fuel mixtures, and low temperature internal combustion required to prevent thermal damage to common aluminum engines! Lower IQ score, cognitive impairment and cognitive decline.
Carbon dioxide/ monoxide : climate change and brain damage : the march beyond 400ppm of atmospheric CO2 : scientists started sounding alarm bells @ 350ppm, including many Nobel award winning scientists. Green house gases are called green house because they trap energy in the atmosphere the way that a greenhouse traps heat for enhancing growing conditions in cooler weather regimes. Climate science is complicated by the Sun's variable output over a multi-decadal cycle, giving rise to political debates concerned with the role that human emissions have on earths atmospheric temperatures. Climate & Weather are always in a state of flue. Dumping billions of tons of a green house gas surely increases the earths solar thermal capture via the well defined green house gas effect.
Crude oil depletion vs international politics & global economics! The public health, land, water and air pollution associated with fracking, refining emissions, upstream and downstream pollution, and the grid energy footprint of electric boilers used for safety heating in the refining process. The high long term cost of lower upfront gas prices encouraging wasteful consumer choices like the Ford F150 as a passenger transport vehicle, noted because it is the most popular vehicle in America.
Gasoline engines achieve peak thermal efficiency at one specific load & RPM setting that can be matched with a electric generator set in a range extending applications to maximize net system efficiency. In the future vehicle final drive will be dominate by instant torque direct drive electric motors (no transmission) that are up to 90% efficient. The thermal efficiency of the gas engine can approach 50% when it is utilized in a gen-set. You can see a decent example of this kind of thing in the Chevy Volt, a range extended electric vehicle (strong hybrid). When gasoline engines are operated a fixed speed and load, the emissions controls can optimized (smaller, lighter, more effective, less expensive).
Gasoline powers roughly 97% of all passenger vehicles sold worldwide as of 2017. The 12000wh/kg of chemical engine in gasoline partially explains its dominate role as a transportation engine fuel. Lithium Ion in its best case achieves only 600wh/kg. Lithium batteries can be recharged up to 3000x in certain chemistries, while gasoline is like a one time use alkaline battery. If you consider the net lifetime energy storage efficiency of lithium, it turns out to be about 150x better than gasoline. This especially noteworthy given that the production of gasoline requires nearly 8kWh of grid energy!
Kinetic energy recover can be achieve using several different technologies. Mechanical flywheel systems in Flybrids, brake energy recovery in battery electric hybrids, and hydraulic energy recovery in hydraulic hybrids. Our Honda Cr-z and Toyota Prius are both gasoline electric hybrids that capture braking energy with electric motor generators that store the generated energy in the battery energy storage system or ESS.
In a traditional vehicle, like our 1992 Subaru Legacy, brake pads squeeze metal brake rotors, slowing the vehicle by producing friction which coverts forward vehicle motion into heat. While this technique works very effectively, it produces metal and brake pad dust emissions, has many failure modes, and is yet another example of unrecovered waste heat in most vehicles. Actually heat in the brake system can cause brake fade, a performance robbing phenomenon.