Week 5

Hybrid Electric Vehicles VS Plug-In Hybrid Vehicles

(1) Hybrid Vehicles:

                                    What Are Hybrid Electric Vehicles and how do they work?

Hybrid Electric Vehicles, also known as HEVs were first developed between 1899 and 1901 by Ferdinand Porshe with the introduction of the Lohner-Porshe Mixte Hybrid to the public. Today's HEVs use an Internal combustion engine (ICE)-and can therefore be fueled like normal cars-but also have electric motors and batteries that could power the vehicle partially or wholly. 

The dual nature of these vehicles has led to the rise of three basic modes of operation which include: regenerative braking, electric motor drive assist and automatic start/stop. Each mode enhances the functionality of the vehicle from maximizing power to energy storage. Examples of a current HEV is the Toyota Prius. 

(2) Plug-In Hybrid Vehicles:

   What Are Plug-In Hybrid Vehicles and how so they work?

Plug In Hybrid Electric Vehicles, also known as PHEVs were developed later that the conventional Hybrid vehicles. As the name suggests these automobiles are powered by rechargeable battery packs (mostly Lithium Ion or Nickel-Cadium), which unlike with the HEV, is the primary source of power of the vehicle. 

There are three different kinds of PHEVs opened for public use. 

(a) The Series Plug In Hybrid: also known as the Extended Range Electric Vehicle (EREV) runs mostly on electricity, Thus despite the presence of ICE, only the electric motors are connected to and can propel the Tyre wheels. 

(b) The Parallel or Blended Plug-In Hybrid: For this kind of PHEV both the ICE and the Electric motors are connected to and can propel Tyre wheels. However at very low speeds this Plug-In operates on 'Electric-only' mode. 

(c) Series-Parallel Hybrid: These kinds of PHEVs have the flexibility to function both the series and the Blended Plug-Ins

Juxtaposing Hybrids, Plug-Ins and Internal Combustion Engine Vehicles 

Figure I

Figure II

The above diagrams give juxtaposed accounts of the of the electricity sources used to charge EVs and PHEVs on grids along with the annual emissions generated from vehicles (covered in for this project) using electricity from the grid, gasoline, or a combination of the two for the entire country (Figure I) and more specifically the state of Pennsylvania (Figure II). 

It is important to note that values provided in the above illustrations are based on certain assumptions made by the Energy Efficiency and Renewable Energy wing of the US department of Energy. Such assumptions include: inputting 23.5 pounds of Carbon-dioxide emission per gallon of gasoline (derived from GREET model), inputting 24.3 miles per gallon on Conventional Vehicles (Corporate Average Fuel Economy-CAFE-standards), 44.4 miles per gallon on HEVs, 37.9 miles per gallon on PHEVs. More details can be found via the US Energy of Department. 

Beyond the Facts and Figures

A major deliverable for the project described in this blog is the Memo that would be addressed to pertinent local and federal authorities who may already be conscious of the scientific facts. What we hope to also emphasize through the Memo (and project report) is the practicality of these vehicles when compared to eachother. Take for example the following: 

(1) HEVs, and PHEVs in particular, use roughly 30%-60% less petroleum than Conventional Internal Combustion Engine Vehicles. They therefore also reduce oil dependence. 

(2) PHEVs, next to Electric Vehicles, emit the least amount of green house gases. However the amount generated depends partly on the fuel used at the electrical power plants. 

(3) Though PHEVs  have less fuel and environmental costs than the Conventional and even Hybrid Vehicles, they are considerably more expensive. With some Plug-In cars valued $4,000-$8,000 more than regular Hybrids. 

REFERENCES

• (1) G.R.E.E.T. life cycle model by Argonne Laboratory, Illinnois 
• (2) US Department of Energy_Energy Efficiency and Renewable Energy
• Alternate Fuels Data Center
• http://www.afdc.energy.gov/vehicles/electric_emissions_sources.html
• Well-to-Wheels Energy Use and Greenhouse Gas Emissions Analysis of Plug-in Hybrid Electric Vehicles
• How HEVs and PHEVs work
• https://www.fueleconomy.gov/feg/hybridtech.shtml