Most Efficient Electric Car

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Selection Criteria

The proposed alternatives for energy source to be used for mass production of a vehicle can be evaluated by comparative analysis with respect to specified essential and desirable criteria. The former is critical for the success of the project and alternatives that don’t meet these requirements will be discarded. On the other hand, desirable criteria are features being sought in an alternative, but is not compulsory for the fulfillment of the project.

Essential Criteria:

The criteria are mandatory for the accomplishment of the project. Alternatives not meeting these requirements will not be considered for the final recommendation.

Overall CO2 emission

Environmental considerations are one of the most important factor of this analysis due to the fact it is the main driver for the production of zero-emission vehicles. However, when analyzing this factor, it is important to take into consideration from well-to-wheel and not isolate the problem to the emission occurring when the car is running. Because these vehicles should replace conventional gasoline-running engines, the threshold for CO2 emission is considered to be the one of a conventional gasoline car of 500g/mile for a cars capable of going up to 400km in one tank. Note that due to the fact that that the emissions of CO2 depend on the distance traveled by the car in one cycle of the battery, a distance of 400 km is used to compare accordingly.

Capital Cost

Economic considerations play an important role in the comparative analysis for finding the best alternative. Specially that the end goal of the project is to have a sustainable business, a hefty capital cost is not attractive for any businessman or investor. Therefore, a threshold of 300$/kWh is used as an essential criterion for any alternative. Note that in this case capital cost represents the total cost to produce the battery for the vehicle using an economy of scale.

Specific Energy

This criterion serves as a measure of the working efficiency of the engine. Sufficient energy production per unit mass by the batteries or fuel cell to run a vehicle is essential for operating a working car. It is assumed that the minimum amount of energy production necessary to have a fully operational car for more than 50 Wh/kg.

Desirable Criteria

This section provides a platform to analyze and compare the alternatives that have me the selected essential criteria. These criteria will enable the selection of the best alternative and are listed in order of relative importance.

Minimal Capital Cost

Even though Capital Cost is also an essential criterion, after discarding alternatives not meeting the requirement, the smaller the capital cost the more attractive the alternative is because a low cost structure would allow for a greater net profit for the business.

Fuel Consumption

An important factor to take into consideration is the fuel or electricity consumption of car since consuming for fuel or electricity will lead to more costs on fuel to cover the same distance. The lower the fuel consumption per km is the more appealing the alternative is.

Minimal Refill time

This criterion is related to the practicality of an alternative. Having to refill your car for a long period of time is not very appealing and thus we lead us to choose an alternative over another.

Maximal Life Cycle

Another important aspect for a battery is its durability. This criterion measures the amount of times the battery can be discharged and charged before becoming unusable.

Minimal Maintenance Cost

Lastly, having low maintenance cost is a factor that can favor an alternative over another due to the fact that high maintenance cost would not be an attractive option for a customer and would therefore find another manufacturer.

Alternatives

Lead Acid Batteries (LAB)

Lead Acid Batteries is considered to be the oldest electric battery, discovered in 1859 by Gaston Planté[7] and benefited from more than 150 years of technical development. The operating principle of the LAB is a chemical reaction described by the following formula (Figure X):

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where U° represent the cell voltage for the standard state. For transportation applications grid-type electrodes (Figure X[8]) are mostly used. The positive and negative grid are kept apart using a separator and are stacked together to yield a cell block housed in a plastic compartment (Figure X[9]). These batteries are usually composed of six cells amounting to 12V.

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The average cost of producing a LAB is 150$/kWh[10]. Moreover, due to the development of the sealed valve regulated lead-acid battery (VRLA) no maintenance is needed which results in maintenance costs equal to 0$[11]. This low cost is offset by the fact the battery is not suitable for regular deeper cycling with a lifetime of 500 to 800 cycles[12]. It has a specific energy of approximately 37.5 Wh/kg[13]. Typical CO2 emissions for a lead-acid battery are considered to be well above 1,000 g/mile[14] for battery capable of covering a distance of 400 km. In addition, its charge time varies from 8 to 16 hours[15]. Lastly, the electricity per mile for a lead-acid battery have an average of 215 Wh/mile[16].

Nickel –Metal Hydride (NiMH)

It would take until the early 1990s for extensive research to start exploring NiMH batteries as an enabling technology for high powered electric vehicles. The operating principle of the batteries is depicted on Figure X[17]:

[pic 6]

As showed for the LAB, the NiMH battery is also composed of positive and negative cells kept apart using a separator that plays a crucial role for maintaining cycle life by holding the electrolyte necessary for ionic transport[18].

The average cost of producing a NiMH battery for an electric car is considered to be below 450$/kWh[19]. Similarly, to the LAB, the NiMH battery don’t have any maintenance costs. Its cycle durability is characterized by lifetime of approximately