Hybrid and electric cars, EV and HV.

Download free PDF books on EV ( electric Vehicles ) and HV ( hybrid cars )

Hybrid cars technology

“EV” and “HV” typically refer to different types of vehicles and powertrains:

EV – Electric Vehicle:

• Definition: An Electric Vehicle (EV) is a type of vehicle that is powered entirely or primarily by electricity. EVs use electric motors and batteries for propulsion.
• Types:
  • Battery Electric Vehicle (BEV): Runs solely on electric power stored in batteries. Examples include the Tesla Model S and Nissan Leaf.
  • Plug-in Hybrid Electric Vehicle (PHEV): Combines an electric motor with an internal combustion engine. PHEVs can operate on electric power or use the internal combustion engine when needed. Examples include the Chevrolet Volt and Mitsubishi Outlander PHEV.

HV – Hybrid Vehicle:

• Definition: A Hybrid Vehicle (HV) is a vehicle that uses a combination of two or more power sources to propel the vehicle. Most commonly, it refers to hybrid electric vehicles that combine an internal combustion engine with an electric motor and a battery.
• Types:
  • Full Hybrid: Can operate on electric power alone, internal combustion engine alone, or a combination of both. The Toyota Prius is a well-known example.
  • Mild Hybrid: Relies on the internal combustion engine as the primary power source and uses the electric motor to assist in specific situations. Examples include the Honda Accord Hybrid.

In summary, “EV” generally refers to vehicles powered exclusively or primarily by electricity, while “HV” refers to vehicles that combine different power sources, often including both an internal combustion engine and an electric motor. The automotive industry has seen significant advancements in both EV and HV technologies, with ongoing efforts to improve efficiency, reduce emissions, and enhance overall performance.

A hybrid car combines two methods for the propulsion of a vehicle. Possible combinations include diesel/electric, gasoline/flywheel, and fuel cell/battery. Typically, one energy source is storage, and the other is the conversion of fuel to energy. The combination of two power sources may support two separate propulsion systems.

 What are fuel cells? Broadly speaking, a fuel cell is an electrochemical reactor that converts the chemical energy of a fuel and an oxidant directly to electricity. More recently, the word fuel cell has been used almost exclusively to describe such a reactor using hydrogen as the primary source of energy. Hydrogen has a long history of being used as fuel for mobility.

More than 200 years ago, hydrogen was used in the very first internal combustion engines by burning the hydrogen itself, similar to burning gasoline today.

However, this did not prove to be quite successful, due to safety concerns as well as low energy density. Rather, in a modern fuel cell, hydrogen is a carrier of energy, by reacting with oxygen to form electricity.

The reaction between hydrogen and oxygen  in a fuel cell

An automotive fuel cell is a device that generates electrical energy through an electrochemical reaction between hydrogen and oxygen. This technology is commonly used in fuel cell vehicles (FCVs) as an alternative to traditional internal combustion engines or battery-electric propulsion systems. The primary components of an automotive fuel cell system include the fuel cell stack, hydrogen storage, and various control systems. Here’s an overview of how automotive fuel cells work:

Fuel Cell Stack:

• The heart of the automotive fuel cell is the fuel cell stack. It consists of multiple individual fuel cells connected in series and parallel. Each fuel cell contains an anode, a cathode, and an electrolyte. Common types of fuel cells used in automotive applications include proton exchange membrane fuel cells (PEMFCs) and alkaline fuel cells (AFCs).

Hydrogen Storage:

• Fuel cell vehicles use compressed hydrogen gas (H2) as the fuel source. The hydrogen is stored in high-pressure tanks onboard the vehicle. The tanks are designed to withstand the pressure required for efficient storage of hydrogen.

Electrochemical Reaction:

• The basic electrochemical reaction in a hydrogen fuel cell involves the oxidation of hydrogen at the anode and the reduction of oxygen at the cathode. The overall reaction produces electricity, water, and heat. 2H2​+O2​→2H2​O+electricity
  

Electric Power Generation:

• As hydrogen gas is supplied to the anode of the fuel cell stack, it undergoes a chemical reaction that releases protons and electrons. The protons move through the electrolyte to the cathode, while the electrons travel through an external circuit, creating an electric current. At the cathode, the electrons combine with oxygen to form water.

Water and Heat Generation:

• One of the byproducts of the electrochemical reaction is water. The combination of hydrogen and oxygen results in the formation of water vapor, which is released as a clean emission. Additionally, the fuel cell process generates heat, which can be used for various purposes, such as heating the vehicle or supporting other thermal management systems.

Efficiency and Environmental Impact:

• Fuel cell vehicles are known for their high energy efficiency and minimal environmental impact. The only direct emission is water vapor, making fuel cells a clean and sustainable technology.

Automotive fuel cells are a key component of the broader effort to develop alternative powertrains for vehicles, reducing dependence on fossil fuels and mitigating environmental impact. While challenges such as hydrogen infrastructure and cost still exist, ongoing research and development aim to improve the viability and accessibility of fuel cell technology in the automotive industry.

The reaction between hydrogen and oxygen is astoundingly simple and can be represented by the following formula: 2H2 +O2 =2H2 O. 5 In a fuel cell, hydrogen and oxygen are introduced separately with hydrogen supplied to one electrode of the fuel cell and oxygen to the other. The two electrodes are separated by a material called the electrolyte, which acts as a filter to both stops the cell reactants from mixing directly with one another and to control how the charged ions created during the partial cell reactions are allowed to reach each other. Hydrogen molecules first enter the hydrogen electrode (called the anode) of the fuel cell.

Conclusion

The hydrogen molecules then react with the catalyst coating the anode, releasing electrons to form a positively charged hydrogen ion. These ions cross the electrolyte and reach the oxygen at the second electrode (called the cathode). The electrons, however, cannot pass the electrolyte. Instead, they flow into an electrical circuit, generating the power of the fuel cell system. At the cathode, the catalyst causes the hydrogen ions and electrons to bond with oxygen from the air to form water vapor, which is the only byproduct of the process.