Treibhaus Gas Emissionen von Fahrzeugen unterschiedlicher Antriebe

Alle Treibhausgase beeinflussen das Klima, unabhängig davon wer sie verursacht. Nur den geforderten "Tank-to-Wheel" (TtW) Wert anzuwenden ist unzureichend da die weiteren Emissionen "Well-to-Tank" (WtT) und "Disposal" grösser sind als die für das Fahren. (Battery-Electric-Vehicle mit 90% erneuerbaren Energien). Es ist daher erforderlich alle Emissionen in einer "Cradle-to-Grave" (CtG) Bewertung aufzuführen, um den tatsächlichen Einfluss des Verkehrs auf das Klima darzustellen.

Die Grafik "Greenhouse Gas Emissions" zeigt die CtG CO2 Emissionen vergleichbarer Fahrzeuge mit unterschiedlichen Antrieben: Konventionell - Elektrik - Hydraulik. Die Angaben beruhen auf Veröffentlichungen [1, 2, 3] und VTI Simulationen.

Batterie-Elektrische Fahrzeuge (BEV) haben im Verhältnis zum Hydraulik Hybrid einen höheren Wirkungsgrad müssen jedoch eine drei- bis vierfach größere Masse (1.200 kg bis 1.500 kg) bewegen und rekuperieren weniger als ein Drittel der Bremsenergie. BEV's werden in der Grafik mit unterschiedlichen %-Anteilen an erneuer-baren Energien dargestellt. Die zum Vergleich herangezogenen 90% erneuerbare Energien (RE) liegen an der oberen Grenze der Erwartungen. Für die verbleibenden Energien sind konventionelle Kraftwerke erforderlich.

Die WtT Daten für den IngoCar berücksichtigen den hohen Ener-gieverbrauch (14x von Stahl) die durch die Carbonfaser Herstellung entstehen.

Importierter "Grüner" Wasserstoff für Brennstoffzellen ist eine öko-nomische Alternative für 2025. [4] Es wird erwartet, dass die druck- und temperaturunempfindliche, aufgeladene Frei-Kolben Maschine mir Abgasenergie-Rückgewinnung einen vergleichbaren Wirkungs-grad (max. 63%) aufweist, jedoch wesentlich robuster, kleiner und kostengünstiger ist.

Im Vergleich mit dem BEV mit 90% RE reduziert der mit Wasser-stoff angetriebene IngoCar H die CO2 Emissions um 60%.

Der "Compact" wiegt 1,360 kg und verbraucht 5,5 L/100km. (VW Golf 1.255 - 1630 kg) Das Raumangebot des IngoCar ist grösser.

Die Emissionen des "Disposal" beruhen auf der Annahme, dass diese 30% der "Production" betragen. Letztendlich müssen alle Bauteile entsorgt werden, auch die Batterien nach einer zweiten Nutzungsdauer in einem nicht-automobilem Bereich. Die Lebens-dauer des Carbonfiber Akkumulators für den IngoCar ist unbe-grenzt. Sie sollte jedoch mindestens die hier angenommenen zwei Lebensdauerzyklen betragen, und das Material ist recyclebar.

Das hydrostatische Antriebskonzept ist auf schwere Fahrzeuge (LKW) mit ähnlichen Vorteilen übertragbar. Gegenüber schweren E-LKW werden deutlich höhere Nutzlasten (+ 8 to / + 70%), Fahr-leistungen und Reichweiten erzielt, zusätzlich zu einer Reduzierung des Verbrauchs von 35% (Frei-Kolben Maschine, Bremsenergie-Rückgewinnung) und den Total Cost of Ownership (TCO) um 15%. 

Eine Studie [5] vergleicht PKW und leichte und schwere LKW mit einem batterieelektrischem Antrieb (BEV), Wasserstoffantrieben (Brennstoffzelle, VKM) und einer konventionellen, benzinbetrie-benen Verbrennungskraftmaschine (VKM). Je nach Verfügbarkeit der Antriebstechnologie und des Energieträgers (Elektrizität, Wasserstoff, Kraftstoff) ergeben sich bei einer WtW Betrachtung Vorteile für die Wasserstoffantriebe bei allen drei Fahrzeugarten.

Wenn Wasserstoff oder Elektrizität vollständig aus erneuerbaren Energien hergestellt werden sind beide Wasserstoffantriebe hin-sichtlich CO2 bei einer WtW Bewertung überwiegend gleichwertig. In einem reinen TtW Vergleich haben BEV (PKW, LKW's) die geringsten CO2 Emissionen - jedoch die höchsten während der Herstellung (WtT) und Entsorgung. Unabhängig von der Art der Energieversorgung erzeugt der Hydraulic Hybrid in allen Bereichen (CtG) die geringsten Emissionen.

In der Studie wird eine wasserstoffangetriebene VKM mit einem Wirkungsgrad von 42.2% eingesetzt. Durch die VKM des Hydraulic Hybrid mit 63% Wirkungsgrad (sehr hoher Mitteldruck, Wärme-dämmumg, Charger compounding, Rankine Zyklus) und voller Rückgewinnung der Bremsenergie, wird daher für alle Fahrzeuge eine merkbare Reduzierung des CO2 in der CtG Bewertung erzielt. Erwartet wird, dass die höheren Kosten für den Wasserstoff generell durch den verringerten Verbrauch kompensiert werden. 

Bemerkenswert: Der IngoCar H erzeugt während seiner gesamten Lebensdauer (300.000 km) weniger CtG Emissionen als die BEV oder Fuel Cell Vehicle (FCV) während der Herstellung.

Die Infrastruktur für den IngoCar ist vorhanden. Die hohen zusätzlichen Emissionen durch die Herstellung elektrischer Antriebe entfallen, und das für 2050 geforderte CO2 Ziel (33 g/100 km) kann mehr als 20 Jahre früher erreicht werden. Die weitere Reduzierung der Emissionen (-40%) durch Wasserstoff (IngoCar H) erfordert Produktionsstätten und Lieferketten deren Erstellung dadurch zeitlich weniger kritisch und kosten-günstiger wird.

Abhängigkeit von ausländischen Materialien

Derzeitige Autos (CC) werden aus einer Vielzahl von Materialien hergestellt deren Versorgung etabliert ist. GHG und Gewicht sind jedoch zu groß, um den erforderlichen geringen Einfluss auf das Klima zu erzielen.

Batterie-Elektrische Fahrzeuge (BEV) erfordern erheblich mehr und teurere, importierte Materialien und erhöhen die Abhängigkeit von ausländischen Quellen, GHG Emissionen, Kosten und sozio-ekonomische Spannungen.

Hydraulic Hybrids (HH) werden mit geringeren Mengen konventio-nellen Materials hergestellt als CC (+942 kg) und BEV (+1,186 kg), aber zusätzlich aus Carbon Fiber verstärktem Plastik (CFRP) (115 kg) für die Energiespeicherung und Plattformstruktur. CFRP erzeugt keine Abhängigkeit von kritischen, importierten Rohstoffen.

Fazit: Die teuren, zusätzlichen Materialien für das BEV's erhöhen die Abhängigkeit vom Ausland ganz erheblich. Die Angaben bezie-hen sich auf die Förderung des Materials. Im Refining von Cobalt hat China einen Marktanteil von 70%. Die GHG Emissionen werden durch die Bereitstellung der zusätzlichen Förder- und Refining-kapazität, sowie die Produktion der Batterien deutlich erhöht.

Die GHG Emissionen (Well-to-Wheel) werden daher für einen langen Zeitraum (2030 +) stark ansteigen bevor die Vorteile der BEV's (Tank-to-Wheel) deutlich zum Tragen kommen. 

 

Greenhouse Gas Emissions of Cars with Various Drive Systems

All Greenhouse gases influence the Climate, independent of who causes them. Considering only the required "Tank-to-Wheel" (TtW) emissions is insufficient since the additional "Well-to-Tank" (WtT) and "Disposal" emissions are higher than for driving. (Battery-Electric-Vehicle with 90% renewable energies). Therefore, it is necessary to quote all emissions in a "Cradle-to Grave" (CtG) evaluation to completely show the actual influence of traffic on the climate.

The graph "Greenhouse Gas Emissions" shows the CtG CO2 emis-sions of comparable cars with various types of drivetrains: Conventional - Electric - Hydraulic. The data are based on publications [1, 2, 3] and VTI simulations.

Battery Electric Vehicles (BEV) operate, in comparison to the Hydraulic Hybrid, with a higher efficiency, but have to move  three to four times the weight (2,650 lbs. to 3,300 lbs.) and recuperate less than one third of the braking energy. The graph shows, BEV's provided with electricity from sources with various % of renewable energy (RE). The 90% RE, as used in this comparison, are at the higher end of the expected capacity needed. Conventional power plants are used to provide the remaining energies.

The WtT data of the IngoCar take the high use of energy for producing carbon fiber material (14x as steel) into account.

Imported “Green” hydrogen for fuel cells is expected to be an econo-mical alternative by 2025.[4] The pressure- and temperature insensitive, charged free-piston internal combustion engine with exhaust energy recuperation is expected to reach a comparable efficiency (max. 63%), while being significantly more robust, smaller, and less expensive.

Comparing the BEV - 90% RE, the Hydrogen driven IngoCar H reduces the CO2 emissions by 60%.

The "Compact" car weighs about 3,000 lbs. and obtains 43 mpg. (VW Golf 2,765 - 3,590 lb.) The IngoCar offers more interior space.

The emissions from "Disposal" are assumed to be 30% of that for "Production". Eventually, all parts of a car must be recycled, even batteries after a second use in a non-automotive application. The carbon fiber accumulator for the IngoCar has an infinitive life. However, it should be sufficient for at least a second lifecycle, as assumed here, and the material is recyclable.

The hydrostatic drive system of the IngoCar is applicable for heavy trucks and provides nearly comparable benefits. In comparison to heavy E-Trucks, noticeable higher payloads (+ 8 to / + 70%), perfor-mances and distances are expected, in addition to a 35% reduction in fuel consumption (Free-Piston Engine, Brake-Energy Recuperation) reducing the Total Cost-of-Ownership (TCO) by 15%.

A newest study [5] compares cars and light and heavy trucks, each equipped with a battery electric powertrain (BEV), hydrogen power-trains (Fuel Cell and ICE) and a conventional, gasoline driven internal combustion engine (ICE). Based on the availability of the powertrain technology and type of energy (electricity, hydrogen, fuel) the hydrogen powertrains provide to most benefits for all three types of vehicles under WtW considerations.

If hydrogen and electricity are fully produced by RE, both hydrogen drive systems are largely equal regarding CO2 equivalents in a WtW comparison. In a pure TtW comparison, the BEV (car, trucks) has the lowest CO2 emissions - but the highest during production (WtT) and Receycling. Independent from the type of energy supply, the Hydraulic Hybrid produces the lowest emissions in all sections (CtG).

The study is based on a hydrogen driven ICE with 42.2% efficiency. The Free-Piston Engine of the Hydraulic Hybrid with 63% efficiency (very high medium effective pressure, LHR, charger compounding, Rankine Cycle) and full recuperation of the braking energy, is expected to provide a noticeable reduction of the CO2 equivalents in a CtG comparison. It is expected, that the higher costs for hydrogen are generally compensated by the reduced consumption. 

Note: The IngoCar H produces during its whole lifecycle (186,000 miles) less CtG Emissions than the BEV and Fuel Cell Vehicle (FCV) during Production (WtT). 

The infrastructure for the IngoCar is established. The large amount of additional emissions from producing the electric drive systems are avoided, and the required CO2 goal (33g/100km) for 2050 can be reached more than 20 years earlier. The further reduction of emissions (-40%) through hydrogen (IngoCar H) requires produc-tion facilities and supply chains which are then timely less critical and costly to build.

[1]    ADAC/Joanneum Research. "Der Treibhausgas-Ausstoß eines Autolebens" 08, 2019
[2]   The Wall Street Journal/University of Toronto. “Are Electric Cars Better for the Environment?", March 23, 2021
[3]   MTZ - Motor Technische Zeitschrift. "Ökobilanzen – Strittig, aber alternativlos", Thomas Siebel, April 2021.
[4]   MTZ - "Wasserstoff - Importoption sticht Vorbehalte aus", Dr. Klaus Schmitz, Arthur D. Little, Juli-August, 2021
[5]   42nd International Vienna Motor Symposium 2021,            Hydrogen Powertrains in Competition to Fossil Fuel based Internal Combustion Engines and Battery Electric Powertrains.                   Sens, Danzer, von Essen, Bauer, Wascheck, Seebode, Kratsch.

Dependency on foreign sources of materials

Conventional Cars (CC) are built from various materials with a well-established supply chain. However, GHG emissions and weight are too high to meet the requirement for a low impact on the climate.

Battery Electric Vehicles (BEV) rely on significantly more and more expensive imported materials, increasing; the dependency on foreign sources of material, GHG emissions, costs, and socio-economic tension.

Hydraulic Hybrids (HH) are built with less conventional material than CC (+2,075 lb.) or BEV (+2,612 lb.) but additionally from carbon fiber reinforced plastic (CFRP) (253 lb.) for the energy storage and support structure. CFRP does not rely on critical imported materials.

Conclusion: The costly, additional materials needed for BEV's sharply increase the dependency on foreign countries. The data listed are for mine production, not fabrication. In refining Cobalt, China has a market share of 70%. The GHG Emissions will increase noticeably due to the construction of the additional mining and refining capacity and the production of the batteries.

Therefore, the GHG Emissions (Well-to-Wheel) will over a long period of time (2030 +) strongly increase before the benefits of BEV,s (Tank-to-Wheel) become significant.   

 

 

[1] Rare earth materials for electric motors not included.
[2] BGR, Bundesanstalt für Geowissenschaften undRohstoffe, https://www.bgr.bund.de
[3] Kritische mineralische Rohstoffe und die neue Geopolitik. Sophia Kalantzakos.https://www.fuw.ch sophia.kalantzakos@nyu.edu,
[4] Conventional Car, medium size, 1,360 kg.
[5] Battery-Electric-Vehicle, medium size, 1,870 kg, weights electric drivetrain, Battery 76 kWh, Union of Concerned Scientists, Fact Sheet, Electric Vehicle Batteries.
[6] Hydraulic Hybrid, medium size, 533 kg, weight accumulator and platform structure, Ingocar, LLC.
[7] Iron/Steel $1/kg (base)
[8] Bauxite (raw material)
[9] Deutsches Kupfer Institut (German Copper Institute)
[10] CC typical material-mix includes Steel, Aluminum, Copper, Nickel, Rubber, etc. 

 

Efficiencies and CO2 Emissions

Mileage and emissions depend on 
 

                                   Well-to-Wheel Efficiency    +     Weight and Size of the car

Well-to-Wheel Efficiency is based on Well-to-Tank Efficiency - the Energy for producing and transporting the energy to the pump or charging Station and the Tank-to-Wheel Efficiency - the Energy used for driving the car. 

The car’s drivetrain transfers the energy into the mechanical power for driving. The amount of power needed is determined by the weight (rolling resistance), frontal area (width, height), and air drag coefficient of the car. In 2021, the Mercedes EQS, has reached an air drag coefficients of 0.200, lower than the predicted coefficient of 0.22 for the Ingocar.

The CO2 Emissions depend on the amount and type of fuel burned, and NOx and Soot on the quality of the combustion. A catalytic converter and filter can reduce the emissions. Not included are the emissions from recycling the batteries or fuel cells. The CFRP accumulators produces significantly less emissions and have principally an infinite lifetime.

 

 References and Footnotes:
  1. Manufactureres, Wikipedia, Journals, Valentin Technologies.
  2. US Department of Energy, www.fueleconomy.gov, Hyundai iX35 0.95-1.4 kg H2/100km (Wirtschaftswoche 37, 2017), applied 1.1 L/100km
  3. MIT – Units & Conversion Fact Sheet, Derek Supple, MIT Energy Club http://web.mit.edu/mit_energy
  4. Values (km/MJ) converted from MPG [2]. Gasoline 121.3 MJ/gal, Diesel 135.5 MJ/gal, H2 120 MJ/gal, Natural Gas 46 MJ/kg
  5. Wikipedia (German) Well-to-Tank Wirkungsgrade, incl.Frischknecht/Tuchschmid, Primärenergiefaktoren von Energiesystemen. Values (%) are available for driving.
  6. Values (km/MJ) are Well-to-Tank efficiency [5].For Honda CNG: Tank-to-Wheel (2.481 MJ/km) is 85% of consumption. 15% (0.438 MJ/km) are Well-to-Tank losses.
  7. Combined Total (2.919 MJ/km) of Well-to-Tank and Tank-to-Wheel energy consumption.
  8. CO2 emissions as CO2Content (g/MJ) [3] divided by Well-to-Wheel (km/MJ) [7] consumption.
  9. Electricity-Mix US (Germany): Coal 33% (22%), NG33% (14.4%), Nuclear 20% (4.6%), Hydro 6% (2.7%), Wind 5% (28.4%), Solar - (22 %) with168 g/MJ ( - ) CO2.
  10. Natural Gas (NG)33% + Renewable Energies (RE) 66% = 20 g/km CO2, requiring a 13-fold increase in wind power energy. |  NG 100% = 59 g/km CO2
  11. Free-Piston engine with NG + reduced air drag (0.20 -small drivetrain, low heat dissipation) improve mileage (200 MPG) and emissions (23 g/km CO2).

 

The total ‘Well-to-Wheel’ energy in MJ/km is the sum of ‘Well-to-Tank’ and ‘Tank-to-Wheel’ consumption. It reflects the requirements for an energy efficient vehicle: Low weight - efficient drivetrain - efficient energy supply chain. 

  1. ‘Electricity Mix’ for Well-to-Tank (battery charger) consumption:
    0.57 MJ/km with 100% Natural Gas (NG) powerplant. Total 1.18 MJ/km.
    0.11 MJ/km with 75% Renewable Energies (RE) plus 25% NG powerplant. Total 0.72 MJ/km
    (Production and transport efficiencies: RE 95%, NG 51.7%)

 

The following graph shows the CO2 emissions and efficiency in km/MJ, based on WTW efficiency.  

The CO2 emissions for the electric cars are based on powerplants operated with 100% Natural Gas (NG). When using current sources of electricity production (Reference 8), the CO2 content increases to 168 g/MJ and the CO2 emissions to 223 g/km (Nissan) and 198 g/km (Tesla) – higher than conventional cars.

For the Tesla, an 'electricity mix' of 50% from powerplants (NG) and 50% renewable energies (wind) is required to reach the same CO2 emissions as the Hydraulic Hybrid. A 40% (NG) and 60% (wind) distribution is required when operating the Hydraulic Hybrid - Ingocar with natural gas (ca. 25 g/km CO2). NG also reduces the NOx emissions significantly.

However, wind and sunshine are not always available, and ca. 30% of the electricity for an electric car (EV) will be produced by conventional powerplants. The resulting influence in the electricity mix (65/35) indicates that an EV will not have lower CO2 emissions than the Hydraulic Hybrid even in long terms. The fine dust through brakes and tires (vehicle weight) remains high.

MPG and km/MJ have the same graphical proportions.

 

 

CO2 emissions from producing batteries (100 kWh) for electric cars.

The manufacturing of a battery (100kWh) for an electric car produces 37,000 lbs. of CO2, this is equal to the CO2 emitted by a comparable conventional car (39 mpg) when driving 62,000 miles. ('Kann das Elektro-Auto die Umwelt retten?', ARD Broadcast (German), June 03, 2019)

The Hydraulic Hybrid 'Ingocar' emits the same CO2 emissions when driving 300,000 miles - a performance the battery can't provide, by far not. The replacement batteries (2 or 3) needed produce an additional 75,000/112,000 lbs. of CO2, and lower emissions than the Ingocar will never be obtained.

These additional emissions are not included in this section due to the lack of data at that time. Including them shows, an electric vehicle will not reach the low CO2 emissions of the Ingocar, even if 80% of the electricity comes from sources of renewable energy. (The remaining 20% is produced by conventional power plants since renewable energy is not always available.)

Remarks:  Hydraulic Hybrid:

Well-to-Wheel Efficiency:  High Well-to-Tank efficiency and an established infrastructure. (Gasoline, Diesel, Natural Gas) High Tank-to-Wheel efficiency through highly efficient hydrostatic drivetrain with energy storage, full braking energy recovery and high degree exhaust-heat-and-pulsation energy recuperation.

Drivetrain Efficiency:  The Hydraulic Free-Piston Engine has high thermal efficiency and homogeneous combustion through ultra-high pressure (3,500 bar) and peripheral fuel injection. Very high, variable compression ratio and piston charger efficiency result in high medium combustion pressure (40 bar +) and power density (kW/kg). No piston side-loads, valve train, and bearing losses. Operation only at the most efficient point for fuel consumption and emissions at nearly constant speed and power. No idling. (See: Section ‘Drivetrain’)

Energy recuperation:  Braking: 75% (100% minus round-trip losses) (Electric cars 20%). Exhaust: Doubling of the expansion ratio through the secondary expansion in the highly efficient exhaust gas driven piston charger - charging the combustion chamber  with air and the accumulator with pressurized fluid. Shock absorber: Dampening energy recuperation.

Weight:  The complete, drivable platform of the Hydraulic Hybrid weighs 293 kg (654 lbs.), that is 120 kg (265 lbs.) less than the battery for a comparable electric car (Tesla Model 3, 310 miles travel). In addition, the accumulator as load carrying backbone of the car, and the crash energy absorbing hydraulic bumper system allow for a very light and less costly car body. The system includes active bumpers at the front, rear and both sides.

Emissions:  Low fuel consumption reduces the CO2 emissions proportionally. NOx and soot are in addition significantly reduced through the ultra-high pressure peripheral fuel injection ring with 24 micro-slots, creating an ultra-fine air-fuel mixture for homogeneous combustion conditions with low emissions for the Free-Piston Engine. A slightly modified version runs on Natural Gas (NG) to reduce CO2, NOx and soot further. (See: Section 'Emissions')

Costs:  The average weight of a medium size 5-seat car (1,540 kg/3,390 lbs) is reduced by 65% (1,007 kg/2,218 lbs) The costs for the 250 kg CFRP (Carbon Fiber Reinforced Plastic) components are lower than the 1,257 kg (1.007 + 250 kg) (2,768 lbs.) of conventional material they replace. (Cost/kg ratio 5:1) The number of parts for the platform are nearly proportionally reduced.

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