Design for the Environment/Batteries for Electric Cars

¾Batteries for Electric Cars store the energy used to power the vehicle. They contribute to the performance, price and range of the car, the key success factors for electric vehicles. Comparing lead acid batteries, ultracapacitors and flywheel systems in electric car applications, ultracapacitors appear to be the superior option, exceling in the criteria above and also in environmental performance.

Project Information

MIE315/415 Section 2 Group B15

• Michael Hamilton (Mhamilton)
• Ammar Khalid (Ammar Khalid)
• Shaheryar Khan (shaheryar)
• Jay Leng (Jayseraph)

Highlights and Recommendations

Ultracapacitors offer superior functional, environmental and economic performance compared to both lead acid batteries and flywheels. The flywheel exhibits better functional performance than the lead acid battery, but is much more expensive and has a much greater impact on the environment. Also, given that there are many years of experience using lead acid batteries in automotive applications, where flywheels are relatively unproven in this environment we would recommend the lead acid battery over the flywheel. However, the ultracapacitor outperforms both of these alternatives in alldimensions analyzed.

Based upon the EIOLCA the ultracapacitor has the least environmental impact of the three alternatives. Over its life cycle it uses the least energy, is reponsible for the least amount of global warming potental and causes the least amount of air pollutions, toxic releases and transfers. Cost analysis also finds that it is the least expensive alternative. Furthermore, it's energy density and specific energy a substantially greater than either other alternative, as described in the functional analysis. However, there is some uncertainty about its ability to achieve the performance claimed by its developer. This will become known soon, as ultracapcitors are expected to be used in electric cars by the end of 200.

Details about the Streamlined Life Cycle Assessment

Streamlined Lifecycle Analysis (SLCA) Results Table

Lifecycle Stage	Materials Choice	Energy Use	Solid Residue	Liquid Residue	Gaseous Residue	Weighted Score
Resources Lead Acid Battery Ultracapacitor Flywheel System	1 3 3	1 2 1	1 1 2	1 0 2	1 0 1	5 6 9
Manufacturing Lead Acid Battery Ultracapacitor Flywheel System	1 3 3	2 1 2	2 1 2	2 2 2	2 4 2	9 11 11
Delivery Lead Acid Battery Ultracapacitor Flywheel System	4 4 3	2 2 2	2 2 2	3 4 1	2 4 2	13 16 10
Use Lead Acid Battery Ultracapacitor Flywheel System	4 4 2	2 2 2	4 4 4	4 4 4	4 4 4	18 18 16
Disposal Lead Acid Battery Ultracapacitor Flywheel System	3 2 2	2 2 2	3 3 2	3 4 3	3 3 2	14 14 11
Total Lead Acid Battery Ultracapacitor Flywheel System						59 65 57

Lead Acid Batteries

Total SLCA score of lead-acid battery is 59. The product use stage gets the highest score, because it won’t generate any residues during the product use stage. The total score of EOL (end of life) stage is also high because the 90% of used lead-acid batteries are being recycled . The pre-manufacturing stage gets the lowest score due to the intensive energy use and industrial hazardous residues generation , which is also the main reason for the low score of SLCA of lead-acid battery.

Ultracapacitors

The overall score for the Ultracapacitor Streamlined Life Cycle Analysis is 65. The product performed well in terms of product use, product delivery and end of life stages. During product use, no solid, liquid or gaseous residues are generated since product uses barium titanate ceramic powder. Moreover, energy storage at about 4-6 minutes consumes significantly lower amount of electricity . For product delivery stage, cardboard a re-useable material will be used for a shipping purpose and could be shipped back during the next shipment for further use. Finally, no liquid residue results since barium titanate powder is closely intact inside the double coating layer . End of life stage scores well because all materials used can be identified and separated upon recycling . In addition, the product has a life of up to a million cycles with out material degradation which is well above the life limit of a car; hence, this product could be placed into the other car once the car life comes to an end making it an environmentally friendly product . EESU did not perform well for the pre-manufacturing stage because virgin materials have been used since recycled material use would result in a lower quality of the product and product may not perform as predicted; however, the composition of virgin materials is kept lowest to reduce the production of large amount of solid, liquid and gaseous toxic residues.

Flywheel Systems

The overall score for the flywheel system Streamlined Life Cycle Analysis is 57. The product performed well in terms of material choice for the pre-manufacturing, manufacturing and delivery stages. The flywheel system is constructed using carbon fiber composite flywheel, aluminum casing and magnetic bearings. The material used to package the finished flywheel system most likely includes foam (cushioning), cardboard (box), and adhesive tape for sealing the box. Both foam and cardboard are recyclable and currently there is a functioning recycling infrastructure available. The system was ranked high for production of residues during the use stage because there are no solid, liquid or gaseous residues produced as the flywheel system operates. The system did not rank well for energy use during the product life cycle because the system operation energy use is dependent on the user and the amount of time the flywheel system is charged for, manufacturing the system is energy intensive and delivery has significant energy requirements because of the distances involved.

Details about the Economic Input-Output Life Cycle Assessment

Economic Input-Output Life Cycle Analysis (EIOLCA) Results Table

Alternative	Total Energy Use [TJ]	Global Warming Potential [MTC02E]	SO2[mt]	CO[mt]	NO2[mt]	VOC [mt]	Lead [mt]	PM10 [mt]	Total Releases [kg]	POTW Transfers [kg]	Offsite Transfers [kg]
Lead Acid Battery	0.199	17.7	0.082	0.046	0.041	0.007	0	0.009	41.955	0.858	3.443
Ultracapacitor	0.177	15.5	0.076	0.023	0.037	0.004	0	0.002	20.543	0.394	1.661
Flywheel System	0.342	34.3	0.158	0.069	0.078	0.011	0	0.011	75.22	1.619	6.249

Lead Acid Batteries

Our EIOLCA found total energy use to be 0.199 TJ, global warming potential (GWP) to be 17.7 MTCO2E and total toxic releases to be 0.271 kg. The product use stage yields high output in energy use and GWP, since the vast majority of energy and greenhouse gas comes from electricity generation and supply during the use stage of the lead-acid battery. The resource extraction and manufacturing stage yields the highest toxic release due to the usage of metal lead during manufacturing stage.

A considerable amount of conventional pollutants are generated from the lead-acid battery life cycle. Product use results in higher quantities of the pollutant emissions than do the other life stage because the electricity generation such as coal-fired power plant produces large SO2 and NO2 emissions. The major CO emissions result from the product delivery sector due to the truck exhaust gases during the delivery process.

Ultracapacitors

In our analysis, an Economic Input Output Life Cycle Analysis was conducted on the EESU for the pre-manufacturing/manufacturing stage, product delivery stage and the product use stage. However, the effect of end of life stage was significantly negligible due to the product’s ability to last up to million cycles whereas an average car’s life is six years; thus, product could be replaced into a new car. For an EESU, the total energy use and the total GWP for the above mentioned included sectors were found to be 0.177 TJ and 15.516 MTCO2E. Both the highest amount of energy used and greenhouse gases emission occur during the product use phase where power generation and supply sector contributes the most. The reason being the amount of electricity required to charge the vehicle daily for the period of six years as well as energy required for power generation. For the coal-fired power plants, the generation of electricity requires extraction of coal during which methane is released into the environment, the transportation of coal (rail, truck) releases carbon monoxide into the atmosphere, “The burning of coal at the plant produces oxides of carbon, usually carbon dioxide in a complete combustion, along with oxides of sulfur, mainly sulfur dioxide (SO2), and various oxides of nitrogen (NOx)”[61]. In addition, the total amount of toxic releases were SO2[mt]=0.076, CO[mt]=0.023, NOx[mt]=0.037 and VOC [mt] = 0.004. As mentioned above, the most pollutant gases are emitted during the product use due to electricity generator power plants. These plants mainly use coal-fired systems which are the main reason for SO2 and NOx emissions. However, Carbon monoxide is emitted during the product delivery due to truck transportation where fuel burning takes place.

Flywheel Systems

An Economic Input Output Life Cycle Analysis was conducted on the system for the Premanufacturing/Manufacturing stage, Product Delivery stage and the product use stage. The Disposal stage was excluded because if we were to incorporate the product disposal stage it would require a separate analysis where data would be required on the test analysis of the flywheel system to determine how many cycles it can sustain. For the flywheel system total energy use for the above mentioned included sectors was calculated to be 0.342 TJ. The main contributor to this value is the power generation and supply sector during the product use stage that requires daily electricity recharging use. The product use stage has the most greenhouse gas emissions which is understandable considering the daily energy consumption and requirement. The generation of electricity requires extraction of coal during which methane is released into the environment, the transportation of coal (rail, truck) releases carbon monoxide into the atmosphere, “The burning of coal at the plant produces oxides of carbon, usually carbon dioxide in a complete combustion, along with oxides of sulfur, mainly sulfur dioxide (SO2), and various oxides of nitrogen (NOx)”. The total GWP value was calculated to be 34.3 MTCO2E. Similarly the amount of toxic releases SO2[mt]=0.158, CO[mt]=0.069, NO2[mt]=0.078 are calculated.

Details about the Functional Analysis

Lead Acid Batteries

The lead-acid battery is an electrical storage device that based on a reversible chemical reaction between lead and sulphuric acid. It has a capacity of six or more volts which is enough to power a vehicle . To power a Ford TH!NK City, twenty-two 110 Ah 12V lead-acid battery of model UB121100 from Universal Power Group Inc. was selected. Each battery has a capacity of 1.32kWh and has average 650 recharge cycles.

Ultracapacitors

Ultracapacitor are energy storage devices that could store tremendous amount of energy, and have the ability to provide both high power and high energy [21]. The car model we have chosen to base our analysis on is the Ford Th!nk City. Th!nk City’s electric battery requires 28.3kWh of energy storage for each recharge [24]. Thus, the model chosen to meet our electric car Th!nk City power demand is EEstor’s Electrical Energy Storage Unit (EESU). EESU could store up to 52kWh of energy [25]; hence, the energy storage capability of an EESU meets or exceeds the demand of the Th!nk City. The total mass of a single EESU is 336lb which includes 272lb of dielectrics, 34lb of nickel and 30lb of copper, and each unit charges within 4-6 minutes with a peak power output of 74.6kW [26]. An EESU has over million numbers of cycles which makes it relatively more environmentally friendly [23].

Flywheel Systems

To power the TH!NK we need 8 flywheel energy storage systems. The flywheel energy storage system consists of the flywheel, aluminum storage system and magnetic bearings. For the sytem, Total Mass = 90 lbs ~ 41kg, Flywheel Alone = 50 lbs ~23kg, Flywheel Diameter = 12 inches = 0.3048m, Flywheel Thickness = 3 inches = 0.0762m, and each wheel stores 4.1 kilowatt-hours of energy. Flywheel conversion efficiency is approximately at 90%. For the flywheel system the number of cycles is almost infinite barring catastrophic failure.

Details about the Cost Analysis

Lead Acid Batteries

The 22 lead-acid batteries are considered as a unique product for the whole life cycle cost analysis. During the analysis, all cash flows are in 2008 US dollars for a consistency. Some costs are calculated in EIOLCA such as the cost for resource and manufacturing, product delivery and product use. Some other costs such as installation and service are calculated by skilled worker’s wage and estimated time. For the life stage of manufacturing, delivery and initial installation, all costs are put into the current year 2008. The 6 years after 2008 are the use stage of the lead-acid battery. Each year has a product use cost, accompany with the service cost. At the end of the battery life (year 2014), the recycling cost will be incurred. The Net Present Value (NPV) was found to be $7193.13 (2008 US dollar). The calculation of the NPV is based on the equation PV (Present Value) = FV (Future Value)/ (1+i) n. Using all the costs in different years and the real discount rate 3.62%, we can calculate the NPV.

Ultracapacitors

The purchase price as mentioned in the EIOLCA of an EEstor Ultracapacitor is $2100 (2007 dollars) [25]. The delivery cost as calculated in the EIOLCA is found to be $15.31 (2006 dollars) for a single EEstor unit. The energy cost of a product during the use phase is also mentioned in the EIOLCA product use phase and is based on Th!nk City’s average life of six years. Thus, we get $288.3 (2007 dollars) for one year. Applying “CPI Inflation Calculator” results in $2144.07, $16.08 and $294.36 (2008 US dollar) for purchase price, delivery cost and energy use respectively. As mentioned in the functional analysis, EESU can be used for over a million cycles [23], whereas, it will be used in the Th!nk City for only 2190 cycles based on six years of daily use; hence, after the car’s life is over, EESU can be taken out and sent back to the manufacturer where it can be reused. Thus, only removal cost occurs at the end of life stage which will be considered to be the same as the installation cost of $13.61(2008 dollars) explained below. Indirect costs should also be considered. Assuming that for installation an electric battery, it takes a skilled automotive worker about half an hour and the average wage for the skilled worker is $27.22/hr [34]; hence, $13.61 (2008 dollars). Finally, service cost is considered to be an indirect cost as well. Assuming the battery is serviced every year for 2 hour including installation and removal time, it will cost $27.22 x 2 = $54.44 (2008 US dollars) each year for up to six years.

Flywheel Systems

The average life of a car is 6 years and an average vehicle travels 18990.2592 kilometers in 6 years. 1 flywheel system costs $818.36 so $818.36 x 8 = $ 6546.88 (1997 US Dollars) which is $8,635.07 (2008 US Dollars). The cost to deliver 889 flywheel systems is $7,792.44 (2008 US Dollars). The cost of electricity used for every kWh is 10.28 cents .The cost therefore is {(0.157kWh/km x 18 990.2592 km) x (10.28cents)} = $306.5 (2007 dollars) per year. The average cost/time ratio for a skilled automotive installer is $27.22/hr . The estimated install time is 20 minutes. Thus, the cost of initial installation of the 8 flywheel systems in 160 minutes is $72.59 (2008 US dollars). We also assume each flywheel system should take a routine 30 minute service each year during the use phase. Therefore to check 8 flywheel systems would require 240 minutes and using the average cost/time ratio $27.22/hr obtained above, we can get the service cost of $108.88 (2008 US dollar) each year. Using a real discount rate of 3.62% the Net Present Value is calculated to be $18,704.78.