Resources

  What are Plug-in Hybrid Electric Vehicles?

DEFINITION: According to the National Renewable Energy Laboratory, a plug-in hybrid-electric vehicle (PHEV) is a hybrid-electric vehicle (HEV) with the ability to recharge its electrochemical energy storage with electricity from an off-board source (such as the electric utility grid). The Institute of Electrical and Electronics Engineers (IEEE) defines a plug-in hybrid electric vehicle as any hybrid electric vehicle which contains at least:
  • A battery storage system of 4 kWh or more, used to power the motion of the vehicle;
  • A means of recharging that battery system from an external source of electricity;
  • An ability to drive at least ten miles (16 km) in all-electric mode, while consuming no gasoline

  Download OEMtek's PHEV brochure

  What is the difference between a Plug-in Hybrid Electric Vehicle (PHEV) and standard hybrid (HEV)?

Essentially, a PHEV uses the same technology as an HEV, but has a more powerful battery pack, capability to plug-in to the electrical grid, and achieves higher MPG performance with unlimited range. Both HEVs and PHEVs are powered by a combination of electricity and gasoline; however, PHEVs not only draw their charge from the engine and captured regenerative braking energy but also from the electrical grid when they are plugged into a standard electrical socket.

  What is the difference between a Plug-in Hybrid Electric Vehicle (PHEV) and an Electric Vehicle (EV)?

PHEVs are powered by two sources: (1) petroleum in the fuel tank and the internal combustion engine; (2) electricity from regenerative braking and from the electric grid. In contrast, EVs are solely powered by electricity. PHEVs do not face the range limitation posed by EVs.

  Why PHEVs?

PHEVs are the next logical step in clean transportation as it provides an increase in fuel efficiency and reduction in GHG emissions, whilst utilizing an energy source that is currently available and has excess capacity. In the future, PHEVs can encompass electric energy in addition to alternative liquid fuels, such as biofuels.

  Why Electric versus other alternative fuels?

  • The electric grid as an energy source has excess capacity in off-peak hours and does not require additional infrastructure investment.
  • Electric and batteries have high efficiency and have the lowest resource consumption per mile compared to other alternative fuels.
  • Batteries are over 80% efficient when transferring electricity into usable power to turn the wheels (after battery and charger losses).
  • The electric grid can use a range of renewable/clean sources of energy to reduce petroleum usage, including wind, solar, geo-thermal, and hydropower.
  • Per unit of power, advanced lithium batteries are also less expensive than fuel cells.

  What about Hydrogen?

Electric is 3x more efficient than hydrogen fuel cells. Less than 20% of the source is usable by the time it reaches the vehicle due to the energy-intensive process of creating hydrogen: (1) electrolysis from water; (2) compression of hydrogen gases into storage; and (3) processing the hydrogen through a vehicle fuel cell system. Also, hydrogen fuel cell powered vehicles will require a high capital investment for hydrogen fueling station infrastructure and a costly fuel conversion process.

  What about other Liquid BioFuels (ethanol, cellulosic ethanol, biodiesel)?

The beauty of PHEVs is that they can utilize biofuels as a replacement for the petroleum in the internal combustion engine to provide even greater reductions in greenhouse gas emissions. However, between ethanol, cellulosic ethanol, and biofuels, there is not yet a clear ‘winner’ that is better than the rest at the moment.

  What about Ethanol?

Electric is 2x more efficient than ethanol. Corn ethanol production would have to use 117 million acres of land to replace 5% of the US gasoline consumption. Also, the average improvement of greenhouse gas emissions reduction compared to petroleum is only 15%. Sugarcane ethanol is available in South American countries, like Brazil, but the US does not plan to produce sugarcane ethanol.

  What about Cellulosic Ethanol?

Electric is 26x more efficient than cellulosic ethanol. Furthermore, cellulosic ethanol is not commercially available and wide-scale utilization could displace native plants and wildlife habitat. If cellulosic ethanol was derived from switchgrass, it would require 35 million acres of land to replace 5% of the US gasoline consumption.

  What about Bio-diesel?

Most of the biodiesel blends used today (292 million gallons/year) is soybean biodiesel. Soybean biodiesel burns represents a 59% reduction in GHG emissions, but would take 138 million acres to replace 5% of the US gasoline consumption and is heavily subsidized. The production of soybean biodiesel leads to increased clearing of forests which could decrease biodiversity and reduced food staple for humans. Cooking grease biodiesel is another biodiesel alternative, which recycles a matieral that would otherwise be discarded. Finally, algae biodiesel is an experimental process using algae grown in large greenhouses that are not yet commercially available.

  Lithium Batteries

July 2007. Exponent Testing Report. Comparison of Selected Lithium-Ion Battery Chemistries.

Exponent completed three comparative tests of lithium ion battery chemistries: (1) the crush test; (2) the external heat test; (and the accelerating rate calorimetry test. Based on these results, it is "improbable" that Valence's lithium iron phosphate batteries will incur the thermal runaway that causes other batteries to burst into flames or explode.

 Download the Full Exponent Testing Report in PDF format.

Valence 18650 Energy Cells Documentation:

 Download the IFR18650 Energy Cell Data Sheet in PDF format.

 Download the IFR18650 Energy Cell Life Cycle Graph in PDF format.

 Download the IFR18650 Energy Cell OCV vs. SOC Performance Graph in PDF format.

 Download the IFR18650 Energy Cell Efficiency Graph in PDF format.

  Environmental Benefits
According to the EPA, transportation accounts for 25% of US annual carbon dioxide (CO2) emissions, and is estimated to grow.

July 2007. EPRI-NRDC PHEV Environmental Study: PHEVs Will Reduce Emissions If Broadly Adopted. Electric Power Research Institute and the Natural Resources Defense Council completed a study on the effects on air quality and greenhouse gas emissions if significant numbers of Americans drove cars that were fueled by the power grid? Among study's key findings were: (1) Widespread adoption of PHEVs can reduce GHG emissions from vehicles by more than 450 million metric tons annually in 2050 – equivalent to removing 82.5 million passenger cars from the road; (2) There is an abundant supply of electricity for transportation; a 60 percent U.S. market share for PHEVs would use 7 percent to 8 percent of grid-supplied electricity in 2050; (3) PHEVs can improve nationwide air quality and reduce petroleum consumption by 3 million to 4 million barrels per day in 2050.

www.epri-reports.org

 www.epri-reports.org/PHEV-ExecSum-vol1.pdf

 www.epri-reports.org/Otherdocs/PHEV-FAQ.pdf

  Extra Capacity in the Electric Grid

January 2007. Pacific National Lab Grid Capacity Study: 84% of today's cars, pick-up trucks and SUVs could be charged off-peak on today's power grid without building new capacity.

The U.S. electric power infrastructure is a strategic national asset that is underutilized most of the time. With the proper changes in the operational paradigm, it could generate and deliver the necessary energy to fuel the majority of the U.S. light duty vehicle fleet. In doing so, it would reduce greenhouse gas emissions, improve the economics of the electricity industry, and reduce the U.S. dependency on foreign oil. Two companion papers investigate the technical potential and economic impacts of using the existing idle capacity of the electric infrastructure in conjunction with the emerging plug-in hybrid electric vehicle (PHEV) technology to meet the majority of the daily energy needs of the U.S. LDV fleet.

 PHEV Feasibility Analysis

October 2006. US DOE/NREL Study: Examining Optimal Charging of PHEVs.

An Evaluation of Utility System Impacts and Benefits of Optimally Dispatched Plug-In Hybrid Electric Vehicles. A 50% penetration of PHEVs would increase the per capita electricity demand by around 5-10%, but would not require additional generation capacity.

  Reducing Our Dependence on Foreign Oil

Global oil consumption has doubled in the last 30 years…and continues to rise


World crude oil demand has grown at around 2% per annum and is expected to increase 37% by 2030, according to the US-based Energy Information Administration's (EIA) annual report. Demand will hit 118 million barrels per day (bpd) from today's existing 86 million barrels, driven in large part by the transportation sector1. Thriving economies such as China and India are quickly becoming large oil consumers. China’s oil consumption grew by 8% yearly since 20022.

The U.S. consumes 25% of the world’s supply (20.5 million barrels) of oil with 69% of the demand driven by transportation


The transportation sector is the fastest growing worldwide in terms of energy demand. Transportation accounts for ~69% of the oil used in the US , and 55% of oil use worldwide. According to the Wall Street Journal, new demand for personal-use gas-powered vehicles (cars and trucks), will cause 75% of the increase in oil consumption by India and China between 2001 and 2025. Improving the fuel-economy of gas-guzzling personal vehicles worldwide will greatly reduce the dependence on oil as an energy source.

If PHEVs are broadly adopted, they can displace 15-20% of today’s daily petroleum consumption.

July 2007. EPRI-NRDC PHEV Environmental Study: PHEVs Will Reduce Emissions If Broadly Adopted. If PHEVs represented 60% of the U.S. market share of transportation, they can improve nationwide air quality and reduce petroleum consumption by 3 million to 4 million barrels per day in 2050.

http://www.epri-reports.org

  1. EIA, http://www.eia.doe.gov/oiaf/ieo/oil.html
  2. EIA, http://www.eia.doe.gov/emeu/international/oilconsumption.html

  Economic Benefits

PHEVs cut the cost of driving to $0.02 to $0.04/mile versus $0.08 to $0.20/mile for gasoline cars.



The national average of gasoline at the pump has stayed between $2.25 and $3.25 in the last two years in the United States. This compares to $0.80 per gallon equivalent for PHEV electric “fill-up”3

October 2006. NREL Study: Cost-Benefit Analysis of Plug-In Hybrid Electric Vehicle Technology.

The large petroleum reduction potential of PHEVs provides strong justification for governmental support to accelerate the deployment of PHEV technology.

 Cost-Benefit Analysis of Plug-In Hybrid Electric Vehicle Technology

  1. Calculation based on the average rate for electricity in the US of $0.0877 per kWh in March 2007, EIA.

  Vehicle-to-Grid
Vehicle-to-Grid4

Research has suggested that the most promising utility markets for V2G power are for the ancillary services for which hourly wholesale markets exist: power-regulation and spinning reserves.

These services require fast and accurate responses to electric grid operator signals, and typically are used for short durations. Grid operators across the country require each of these services for every one of the 8,760 operating hours in a year, and they represent a multi-billion-dollar combined market.
—“Electric and Hybrid Vehicles: New Load or New Resource?”

Regulation (frequency response) services today are used to increase or to decrease grid power in a specific area. If demand is greater then supply at any given moment, then regulation up is required. If demand is less than supply, then regulation down is required. With a PHEV in the loop, regulation up would discharge the battery, and regulation down charge the battery.

Spinning reserves are used to deliver fast power to the grid in case of a sudden contingency, such as a scheduled generator tripping offline, or the failure of a transmission or distribution facility. Spinning reserves, when called upon, are required for only a short period.

Central to these schemes is having the utility have control of the timing of the charging and the discharging, and therefore the use of intelligent grid technology.

This excess capacity could potentially provide electricity to PHEVs provided the utilities have some control over when charging occurs. We did not evaluate system-wide effects of uncontrolled charging; however, we would anticipate significant negative impacts if this were allowed at a large scale.
—Denholm and Short, NREL report

Additional Resources on V2G:
  1. Excerpted from Green Car Congress