Week 11 - Chapter 16 - New Motors: EVs, NGV, Hydrogen FCV Flashcards
(30 cards)
Electric vehicles (EVs)
Electrification of automobiles and other vehicles
Hybrid EV (HEV)
Has both combustion engine and electric motor.
This process of developing a hybrid EV (HEV) started with approaches to capture latent wasted energy in a vehicle, often through recapturing energy from braking (regenerative braking), which could then be used to power onboard systems and provide additional energy to the powertrain of a vehicle. The systems continue to evolve to support engine power for acceleration and can even allow the vehicle to run in electric-only mode for short periods.
What traditional HEVs lack is a way to provide supplemental, or external, electrical energy to increase the range and contribution of electric propulsion to overall vehicle operation.
Regenerative braking
The process of recapturing energy from braking in a HEV, that can be used to power onboard systems and provide additional energy to the powertrain of a vehicle.
Plug-in hybrid EV (PHEV)
HEV with chargers and additional battery capacity.
What traditional HEVs lack is a way to provide supplemental, or external, electrical energy to increase the range and contribution of electric propulsion to overall vehicle operation. Solving this problem requires adding chargers and additional battery capacity, converting these vehicles into plug-in hybrid EVs (PHEVs). Depending on the battery capacity, these vehicles can substantially extend the average daily commuting range (as compared to the BEVs discussed below), while still providing the flexibility for longer trips or overcoming the difficulty and uncertainty in accessing EV charging infrastructure through the onboard ICE components.
Battery EV (BEV)
Vehicles exclusively powered by electricity, stored in batteries.
In contrast to the hybrid approach, the second (revolutionary) path for developing EVs has been to start with the simplest vehicle design platform and rely exclusively on electricity to power the vehicle, eliminating any ICE components.
Developing these battery EVs (BEVs) allows manufacturers without experience in traditional ICEs and mechanical drivetrains to create a complete vehicle. It also requires a minimum number of parts to establish a working vehicle, needing only battery storage, motors, and charging components. Such simple configurations minimize complexity and cost in new vehicle design.
Powering a vehicle using only electric motors has many technical advantages. They are extremely efficient, with conversion efficiencies of over 80%. They have high torque, which can provide power at low speeds and quick acceleration, providing very high power-to-weight ratios compared to combustion engines. Typically, electric motors will turn an axle for vehicle propulsion, but, increasingly, smaller motors are being applied to individual wheels and can even be distributed directly into the wheel base, further enhancing efficiency and operational control.
Flex-fuel vehicle
Vehicles that can accommodate multiple fuels (in this case liquid fuel and electricity)
PHEV proponents argue that the flexibility of their platform is more suitable to mass-market applications, providing a flex-fuel vehicle that can accommodate both liquid fuel and electricity.
Level 1 charger
This 120V charger relies on standard plugs and outlets for small US electrical devices. Charging a vehicle using this method provides roughly 4.5 miles per hour of charging.
Level 2 charger
Level 2 charger—This type of charger is rated to operate at 208V or 240V, and the power draw can range from 3.3 to 19.2kW, depending on the configuration.
It can use a dryer plug type of connector (named because of its common use for clothes dryers in the United States), but it is increasingly moving to a more durable and easier-to-operate plug called the SAE J1772, now standard on most commercial US EVs. In Europe, the European Commission mandated Level 2 plug is slightly different, and is known as the Mennekes plug after the company that manufactures it.
DC fast charger
DC fast charger—This type of charging is available for commercial-grade charging stations, as they require a power input of 500V DC and can have power draws of over 60kW.
While this is enough power to fully charge a BEV in about 30 minutes, the amount of equipment and electrical infrastructure to safely provide this charge is substantial. There are three different charger plugs for this type of vehicle, including the CHAdeMO, the combined charging system (CCS), and Tesla’s proprietary standard. The CCS plug is built by expanding the design of the SAE J1772 plug and adding DC charging elements with the intent of creating a single standardized plug for both AC and DC charging.
Battery swapping
An alternate strategy to provide faster charging of EVs is through battery swapping. Battery swapping requires the design of an EV to allow quick removal of the depleted battery and the necessary equipment to replace it with a charged battery, almost certainly requiring the infrastructure of a commercial battery-swapping station.
Discharge
While charging the battery delivers potential energy to it, the discharge of the battery allows the vehicle to move and perform work.
Useful capacity
The fraction of a battery’s absolute capacity that can be used, since it cannot be charged to 100% or discharged to 0% of technical capacity without sustaining impacts to long-term performance.
First, a battery’s useful capacity is very different from its absolute capacity, as a battery cannot be charged to 100% of its technical capacity (the percentage of the technical capacity being used is referred to as the state of charge) without risking damage to the molecular structure of the battery, shortening its useful lifetime. A battery also cannot be discharged to 0% without similar damage and risk to long-term battery performance.
As such, there is a useful range of battery performance, the useful capacity, which is a fraction of the overall battery capacity.
Calculations of the amount of energy that a battery can store, and the resulting range it can travel (an EV analogue to miles per gallon, as discussed in the Metrics Sidebar below), should be based on the useful capacity value of its battery. The cost of the battery pack, however, will be based on the total capacity.
Vehicle protection mode
Mode entered when BEC approaches minimum safe state of charge, shutting off non-core power uses, and eventually shutting off completely.
As a BEV approaches its minimum safe state of charge, it enters a vehicle protection mode that alerts the operator and limits the operating parameters of the vehicle through reduced ancillary power use (turning off air conditioning or radio functions, for instance) and speed until additional charge can be supplied.
Total cost of ownership (TCO)
Levelized costs of owning a vehicle, derived by breaking down the fixed cost of owning the vehicle and amortizing it over its useful lifetime and the variable cost of operating a vehicle (fuel and maintenance). Standardized on a cost per mile basis.
The basic economic analysis for vehicle ownership is similar to the levelized cost methodology established elsewhere throughout this book, beginning with LCOE in Chapter 5. Levelized costs involve breaking down the variable cost of operating a vehicle, including fuel and maintenance, and the fixed cost of owning the vehicle and amortizing it over its useful lifetime. In transportation, this combined levelized cost is sometimes referred to as the total cost of ownership (TCO), described for ICE vehicles in Chapter 13.
a) Operating cost
b) Battery cost, cycle life
c) Cost per Mile
Well-to-wheels efficiency
Overall system efficiency of delivery fuel to ICE or BEV vehicles, better for BEV, which is why variable costs are lower for BEV.
Delivering electricity from its primary source to the vehicle incurs higher losses than delivering refined fuels to ICEs. Well-to-pump efficiency for refined fuels is usually better than electricity generation using other forms of fossil fuels like coal or natural gas that suffer from upstream combustion losses, but overall system efficiency (well-to-wheels efficiency) still favors electricity-based methods, which is why the resulting variable energy costs are typically lower for electric propulsion than for refined fuels.
Cycle life
The number of cycles a battery can withstand before being depleted (or at least no longer useful for transportation purposes).
A TCO calculation requires a similar approach. However, since the lifetime of the battery is typically measured in terms of cycles, rather than calendar life, estimating the number of cycles a battery can withstand before being depleted (or at least no longer useful for transportation purposes) is an ideal way to measure the battery lifetime. This cycle life needs to be averaged over the distance, such as number of miles that an average charge and discharge cycle provides to the vehicle owner, resulting in a fixed cost per mile for depleting the battery life.
Cost per mile (CPM)
Used in TCO calculation to standardize all operating and fixed costs, and allow comparability among transportation options.
Total potential market
From the perspective of the manufacturer of an EV, the total potential market in which it could compete would include any vehicles that might be electrified.
The total potential market should be the entire fleet of vehicles sold in a given year around the world, or the entire 80 million new passenger vehicles sold, plus any future organic growth.
Adoption constraints
The limits that reduce the Total Potential Market to become the Total Addressable Market:
- Economic constraints
- Substitutability constraints
- Access to pairing technology (infrastructure)
- Investment constraints
- Market failures
- Behavioral and social constraints
Total addressable market (TAM)
The Total Potential Market after accounting for adoption constraints.
The realistic market that manufacturers can expect to penetrate with their product. Still constrained by their sales & marketing efforts vs. the competition.
Range anxiety
A consumer concern about how far they can go on a single charge and whether they can perform all of their necessary transportation tasks without running out of charge or going too far out of their way to recharge. major constraint on BEV adoption and use.
Override premiums
Additional price that consumers might need to pay to charge in peak times when the utility is aiming to restrict power consumption.
Establishing override premiums can allow vehicle charging even during peak times for customers unwilling to follow these restrictions or in critical circumstances that require charging.
Lifecycle emissions
The amount of GHG emissions creating during vehicle manufacturing, fueling/charging, and other uses.
Lifecycle emissions are calculated using the lifecycle analysis methodology discussed in detail in Chapter 20.
Because EVs need to be charged using grid electricity, full lifecycle analysis of their emissions has to include upstream emissions generated by the mix of electricity being used to power the grid, including all of the efficiency losses incurred through the supply chain.
In almost any comparison, EVs have lower GHG emissions than their ICE counterparts, but exactly how much lower depends on the generation mix in the particular country.
Vehicle-to-grid (V2G)
The collection of methods enabling grid-connected vehicles to offer grid services.
Beyond the local constraints of cluster effects and strain on grid resources and generators, more vehicles deployed with batteries and plugs can eventually support the grid and improve overall reliability and cost of operation.
The collection of methods enabling grid-connected vehicles to offer these services is referred to as vehicle-to-grid (V2G).
Hypothetically, vehicles plugged into the grid can offer grid services by tapping into the storage capabilities in their batteries. As with other battery applications, EVs can provide standby power, frequency regulation, other short-term power applications, and even some types of energy arbitrage by charging at times of low energy price and discharging at times with higher prices.
