EV Energy analysis

First step in looking the energy cycle of Electric vehicle is to look into the battery technology and raw material used in the electric vehicle. There are a number of environmental impacts that are exacerbated by the use of raw materials in larger quantities or exclusively in BEVs such as greenhouse gas (GHG) and air pollutant emissions from energy-intensive mining and refining processes, health and ecosystem impacts of air pollution from metallurgical processes and water and soil contamination from mining activities , ecosystem impacts of land use for mining, depletion of critical raw materials. The processes involved in raw material sourcing, which include extraction, separation and refining, are resource intensive. Large volumes of water, energy and other substances such as ammonia are consumed. This contributes to making material extraction and processing into a useable form a significant contributor to energy use and correspondingly GHG. Estimates of the GHG emissions from raw material extraction and processing for Li-ion batteries vary widely, but recent Life cycle assesment (LCA) suggest that it is responsible for around 20 % of the total GHG emissions from battery production. The energy used in raw material extraction and processing may be in the form of electricity, heat or fossil fuels used in vehicles and machinery. Compared with BEV manufacture and use, in which electricity is the dominant energy source, a larger proportion of the energy demand for raw material extraction and processing comes from fuel combustion in vehicles and to provide heat. For the portion of energy provided by electricity, the climate change impact depends on the carbon intensity of electricity generation types feeding into the grid at the time and location of use. This varies considerably by country: those with the highest carbon intensity are those where coal-fired power stations dominate. Mining processes, the release of toxic emissions and leakages of toxic substances can have harmful impacts on human and ecosystem health such as eutrophication, acidification of water bodies and wetlands, soil contamination with heavy metals and soil Erosion.

A large proportion of GHG emissions and air pollutants released during BEV production are related to generating electricity and other forms of energy required for energy-intensive processes. Most LCAs of BEVs find that battery production is responsible for the largest proportion of energy use (and GHG emissions) in the production phase with estimates ranging between 10 and 75 % of manufacturing energy and 10 and 70 % of manufacturing GHG emissions. A recent review found that all stages of battery production account for 33‑44 % of total BEV production. Of this total, LCAs report that cell manufacturing and battery assembly accounts for anything between 3 and 80 % of total battery production emissions depending on the approach taken, with the rest arising from raw material extraction and processing. Considering other vehicle components, the electric motor contributes around 7-8 % of total production‑related emissions (including raw material extraction) because of the high copper and aluminium content, other power train components with a high aluminium content contribute 16-18 %, and the remainder of the vehicle contributes around 35 % . Electricity has to be transmitted from large power plants to the consumers via extensive networks. The transmission over long distances creates power losses. The major part of the energy losses comes from Joule effect in transformers and power lines. The energy is lost as heat in the conductors. Considering the main parts of a typical Transmission & Distribution network, here are the average values of power losses at the different steps:

• 1-2% – Step-up transformer from generator to Transmission line

• 2-4% – Transmission line

• 1-2% – Step-down transformer from Transmission line to Distribution network

• 4-6% – Distribution network transformers and cables The overall losses between the power plant and consumers is then in the range between 8 and 15%.

Losses scale with the square of a wire’s current. That square factor means a tiny jump in current can cause a big bump in losses. Keeping voltage high lets us keep current, and losses, low. Generally, smaller power lines mean bigger relative losses. So even though electricity may travel much farther on high-voltage transmission lines – dozens or hundreds of miles – losses are low, around two percent. And though your electricity may travel a few miles or less on low-voltage distribution lines, losses are high, around four percent. Transmission and distribution losses tend to be lower in less densely populated region because less densely populated region have more high-voltage, low-loss transmission lines and fewer lower-voltage, high-loss distribution lines. Transmission and distribution losses vary country to country as well. Some countries, like India, have losses pushing 30 percent. Often, this is due to electricity thieves. Unlike conventionally fueled vehicles, electric vehicles experience a loss of energy during “refueling,” with an energy loss of about 16% from the wall power to the battery during charging. However, electric vehicles are otherwise highly efficient, delivering 60%-65% of the energy from the wall power to the road even before energy is reclaimed through regenerative braking. When energy gains from regenerative braking are included, the amount of energy used for traveling down the road can rise to more than 80%. By contrast, only 12-30% of the energy put into a conventional car is used to move the car down the road; the rest of the energy is lost to engine inefficiencies or used to power accessories.