Thursday, January 19, 2017

Understanding NGV methane emissions

From US Gas Vehicles:

A newly published scientific study, led by researchers with West Virginia University at the Center for Alternative Fuels, Engines and Emissions, measured methane emissions from heavy-duty natural gas-powered vehicles and refueling stations, and is greatly expanding what we know about emissions from natural gas-fueled vehicles. The study is the first project in Environmental Defense Fund’s coordinated methane research series to analyze where and by how much methane emissions occur during natural gas end uses.

The WVU study found that emissions from the vehicle tailpipe and engine crankcase were the highest methane sources, representing roughly 30 and 39% (respectively) of total pump to wheels (PTW) emissions. Fortunately, engines with closed crankcases have recently been certified by EPA, avoiding the single largest source of methane emissions from these vehicles.

Fueling station methane emissions were reported to be relatively low, representing about 12% of total PTW emissions. WVU researchers based the fueling station emission estimates on the assumption that liquefied natural gas (LNG) stations have sufficient sales volume to effectively manage boil off gases, or the fuel lost as vapors when the LNG heats above its boiling point. Without alternative methods to manage boil off gas, low sales volume risks large methane releases.

Eleven industry groups participated in the WVU study – The American Gas Association, Chart, Clean Energy, Cummins, Cummins Westport, International Council on Clean Transportation, PepsiCo, Shell, Volvo Group, Waste Management, and Westport Innovations – and provided researchers with important insights. Their active involvement and determination to go where the science led them in reducing truck methane emissions greatly strengthened the study.

Measurements from the WVU study are helping to further our understanding of the climate impact of natural gas vehicles. This paper, along with other analyses, provides both industry and policymakers new insights to target technology improvements, and identify best practices for minimizing emissions. But pairing vehicle data with lifecycle emissions of methane across the entire supply chain remains essential to fully assess how natural gas trucks perform, from a climate perspective, relative to diesel trucks.

While only about 3 percent of heavy duty trucks run on natural gas today, some analysts suggest their market share could reach as high as 50 percent over the next two decades if high oil and diesel prices return. Meanwhile, investments in natural gas-powered utility vehicles and transit buses are growing, with 11 percent of such vehicles already running on natural gas.

Tuesday, January 3, 2017

Ideas Are Scary

From Greg Roche, Vice President at Clean Energy Fuels:
GE runs a great commercial about how ideas are scary; frightening because they threaten what is known; and are the natural born enemy of the way things are. You can watch the commercial here (with thanks to GE). What does this have to do with renewable natural gas trucks? Everything. Imagine switching all 12,000 to 16,000 trucks that operate in the Port of Los Angeles and the Port of Long Beach from diesel to renewable natural gas (RNG). Would that be scary to some? Sure. Would that threaten what is known? Yes. Would that replace the way things are? Absolutely. But the upside is what makes this idea beautiful: achieving cost-effective and immediate health and sustainability benefits. In fact, natural gas trucks with Near Zero emissions technology and powered by renewable natural gas reduce harmful air pollutants by over 90% and reduce greenhouse gas emissions by over 70% compared to diesel, making renewable natural gas trucks as clean as a battery electric truck on a complete well-to-wheels comparison. Ideas may be scary, but scary shouldn't be allowed to stop the idea.

Thursday, December 22, 2016

How fuel economy is determined and reported for alternative fuel vehicles

Question of the Month: How is fuel economy determined and reported for alternative fuel vehicles?

Answer: Last month we learned about how the U.S. Environmental Protection Agency (EPA) determines and reports conventional light-duty vehicle fuel economy ratings. While alternative fuel vehicle (AFV) fuel economy testing is largely similar to that of conventional fuels, the EPA makes some adjustments to account for different vehicle technology and fuel energy content. By tailoring AFV fuel economy testing and reporting, the EPA is able to provide apples-to-apples comparisons and allow consumers to make informed decisions.

All-Electric Vehicles

What's Reported: The fuel economy label for all-electric vehicles (EVs) includes all of the same information as that listed for gasoline vehicles (fuel economy, fuel cost savings, annual fuel cost, and emissions). However, EV labels list fuel economy using miles per gallon of gasoline-equivalent (MPGe), sometimes referred to as miles per gasoline gallon equivalent (MPGGE). MPGe represents the number of miles a vehicle can go using a quantity of fuel with the same energy content as a gallon of gasoline. MPGe is a useful way to compare gasoline vehicles with vehicles that use fuel not dispensed in gallons. EV labels also include the following information:

  • Vehicle Charge Time: Indicates how long it takes to charge a fully discharged battery using Level 2, 240-volt electric vehicle supply equipment.
  • Driving Range: Estimates the approximate number of miles that a vehicle can travel in combined city and highway driving before the battery must be recharged.
  • Fuel Consumption Rate: Shows how many kilowatt-hours (kWh) of electricity an EV would use to travel 100 miles. Like gallons per 100 miles, the kWh per 100 miles relates directly to the amount of fuel used. It is an estimated rate of consumption rather than economy (measured in miles per gallon [MPG] or MPGe), which allows for more accurate energy usage comparisons between vehicles.

What's Tested: To test EV fuel economy, the vehicle battery is fully charged and the vehicle is parked overnight. The next day, the vehicle is tested over successive city cycles until the battery is depleted. The battery is then recharged and the energy consumption of the vehicle is determined by dividing the kWh of energy needed to recharge the battery by the miles traveled by the vehicle. MPGe is based on this figure. The process is repeated for highway driving cycles, and the combined city and highway fuel consumption and MPGe is based on the standard ratio of 55% city and 45% highway driving.

Plug-in Hybrid Electric Vehicles

What's Reported: Like EVs, plug-in hybrid electric vehicle (PHEV) fuel economy labels include fuel cost savings, annual fuel cost, and emissions information. For PHEVs that can use either electricity or gasoline (but only one fuel at a time), also known as non-blended or series PHEVs, labels include information for the fuel economy of both fuel modes. The electricity information is identical to that of EVs, listing charge time, fuel economy in MPGe, and fuel consumption rate in kWh per 100 miles. The gasoline information provides fuel economy in MPG and fuel consumption information in gallons per 100 miles. PHEV fuel economy labels also include electricity only, gasoline only, and combined electricity and gasoline driving range estimates. For PHEVs that use electricity and gasoline at the same time, also known as blended or parallel PHEVs, fuel economy labels reflect the fuel economy, fuel consumption, and range of the vehicle when it uses its standard electricity and gasoline mix.

What's Tested: Because series PHEVs can use either electricity or gasoline, the EPA determines a vehicle's fuel economy and fuel consumption based both on its use of only electricity and only gasoline. To determine a PHEV's electric fuel economy, the EPA issues testing methodology nearly identical to that of EVs. If the gasoline engine is required to complete the test cycle, the EPA methodology uses both the electric energy consumption and the gasoline consumption to calculate the MPGe values for the electric operation only. Vehicle testing for the gasoline operation of the vehicle is similar to any other conventional hybrid electric vehicle. Parallel PHEVs are tested using their standard mix of electricity and gasoline.

Other Alternative Fuels

What's Reported: The EPA also requires fuel economy information for original equipment manufacturer (OEM) vehicles that use alternative fuels. This includes dedicated natural gas, propane, and hydrogen vehicles, as well as bi-fuel vehicles, such as bi-fuel natural gas, propane, and flexible fuel vehicles (vehicles that may use 51%-83% ethanol-gasoline blends). Note that the EPA does not require fuel economy testing of vehicles converted to run alternative fuels after they are purchased. While the EPA does not list fuel economy information for vehicles that use biodiesel, all diesel vehicles may use fuel blends of up to 5% biodiesel. These vehicles achieve fuel economy very similar to conventional diesel.

For vehicles that use exclusively alternative fuels (e.g., natural gas or hydrogen), the EPA lists fuel economy in MPGe in order to accurately reflect the fuel's energy content and make easy comparisons with conventional fuel vehicles. Vehicles that can use either alternative fuels or conventional fuel, such as bi-fuel natural gas, bi-fuel propane, and flexible fuel vehicles, have fuel economy, fuel consumption, and range estimates for both the alternative and conventional fuel listed on their fuel economy labels. Fuel economy for alternative fuel use in bi-fuel and flexible fuel vehicles is listed in MPGe, while fuel economy for conventional fuel use is listed in MPG.

What's Tested: For vehicles that run exclusively on alternative fuels, fuel economy testing methods are similar to those of conventional vehicles. For bi-fuel and flexible fuel vehicles, the vehicle fuel economy is tested as it runs exclusively on each fuel, similar to PHEVs.

For more information about AFV fuel economy, see the website and select from the Advanced Cars & Fuels menu. Also, view the Fuel Economy Toolkit.

Happy Holidays!

Clean Cities Technical Response Service Team

Saturday, November 26, 2016

How Much Do You Know About Fuel Cells

Quiz: How Much Do You Know About Hydrogen and Fuel Cells?
Hydrogen and fuel cell technologies power cars, buildings, and more. But how much do you know about them?

Test your knowledge with this recent Energy Department blog post, Quiz: How Much Do You Know About Hydrogen and Fuel Cells?

Friday, November 25, 2016

Question of the Month: How are conventional light-duty vehicle fuel economy ratings determined and reported?

Answer: It's important to understand the who, what, when, where, and why (and how!) of fuel economy testing and labeling. In particular, you may be interested in the recent changes described below (see "When" section).

"Who" is tested?
Most light-duty vehicles must be tested for fuel economy. Exceptions include motorcycles, pickup trucks and cargo vans with a gross vehicle weight rating (GVWR) above 8,500 lbs., and passenger vehicles with a GVWR above 10,000 lbs.

Original equipment manufacturers (OEMs) test a representative vehicle for each light-duty model and report the results to the U.S. Environmental Protection Agency (EPA). The EPA reviews the results and confirms estimates for about 10% to 15% of the vehicles through tests at the National Vehicles and Fuel Emissions Laboratory (NVFEL).

How are vehicles tested?
Vehicles are tested in a laboratory using a standardized procedure established by the EPA. The vehicle's drive wheels are placed on a machine called a dynamometer that simulates the driving environment—much like an exercise bike simulates cycling. The energy required to move the rollers is adjusted to account for wind resistance and the vehicle's weight. On the dynamometer, a professional driver runs the vehicle through standardized driving routines, which simulate "typical" trips in the city or on the highway. Each driving routine specifies the speed the vehicle must travel during each second in the test. To measure the fuel economy of the vehicle, a hose is connected to the tailpipe to collect the engine exhaust during the tests. The carbon in the exhaust is measured to calculate the amount of fuel burned.

From there, the manufacturer enters the test results into an equation the EPA has established to determine the final city and highway fuel economy estimates (see the Code of Federal Regulations, 40 CFR 600.210-12, for more information. Combined city/highway fuel economy is calculated by weighting the city miles per gallon (mpg) value by 55% and the highway value by 45%. Combined fuel economy values provide consumers with a quick and easy comparison point across vehicles.

What information is included on the fuel economy label?
In addition to providing city, highway, and combined city/highway mpg fuel economy estimates, the new fuel economy label provides information about emissions and fuel cost:
  • Comparing fuel economy to other vehicles: The label shows the average mpg rating of similar sized vehicles for users to easily compare fuel economy. It also estimates how much money you would save or spend in fuel costs over five years compared to the average vehicle.
  • Annual fuel cost: Based on annual mileage assumptions, projected fuel price, and mpg rating, the label displays estimated annual fuel cost.
  • Emissions information: The label rates the vehicle on a scale of 1 to 10 for (a) fuel economy and greenhouse gas and (b) smog emissions, making it easier for consumers to choose cleaner vehicles.
  • QR Code: Users are able to scan the QR Code on the label to access helpful tools and additional information about the vehicle's fuel economy and emissions.
When did this rating system come into effect?
The EPA's fuel economy testing and labeling procedures were initially established in the late 1970s and have evolved over time. The EPA updated its fuel economy methodology with MY 2008 vehicles and again this year with MY 2017 vehicles. The 2008 methodology changes incorporated the effects of faster speeds and acceleration, air conditioner use, and colder outside temperatures. These updated methods improved the accuracy of fuel economy estimates.

This year's changes are more subtle. As described in the "How" section above, the EPA is responsible for providing an equation that manufacturers use to calculate the final city and highway fuel economy for their vehicles. Starting with MY 2017 vehicles, the EPA updated the equations used to calculate fuel economy estimates for some vehicles. The updated equations better reflect the more fuel-efficient vehicles and advanced technologies (e.g., hybrids and tubocharged engines) on the road today. While most vehicles will not be affected, some fuel economy estimates will decrease by 1 to 2 mpg.

MY 2011–2016 mpg estimates on have been converted to the new ratings system to allow for easier comparison of fuel economy of newer and older cars.

Where is fuel economy data available?
EPA fuel economy estimates are displayed on the Fuel Economy and Environment stickers affixed to the window of new vehicles. Fuel economy estimates for vehicles from model year 1984 to present are also available online at DOE's website.'s Find a Car tool allows users to search by vehicle make, model and year. The website's My MPG page allows consumers to calculate, track, and post their fuel economy to compare it with the EPA test ratings and other users' posted results. Full fuel economy data is downloadable in PDF or spreadsheet form on

Why does this matter?
Accurate and detailed fuel economy information allows consumers to make informed decisions. Widely available and clearly presented data supports the purchases of clean and efficient vehicles. As always, it is important to remember that the EPA ratings are a useful tool for comparing vehicles because they are always done the same way under the same set of conditions. However, since consumer driving conditions and styles can vary greatly, the fuel economy some drivers achieve may vary from the EPA's estimates. For tips on improving your fuel economy, visit the Factors that Affect Fuel Economy page on

Watch for more information next month on how fuel economy for bi-fuel vehicles, including plug-in hybrid electric vehicles, is tested and reported.

Clean Cities Technical Response Service Team

Thursday, November 10, 2016

Clean Energy Fuels Corporation Still Not Profitable

The supply of natural gas still exceeds demand. The author of this article considers OPEC an unlikely threat to national security. "The optimism concerning natural gas vehicle demand in the U.S. has been and is ahead of its time."

Friday, October 28, 2016

What idle reduction technologies are available for heavy-duty vehicles?

Question of the Month: What idle reduction technologies are available for heavy-duty vehicles?

Answer: Heavy-duty vehicle idling, or running a vehicle's engine while it is not in motion, occurs for a number of reasons, including temperature control during required rest stops, powering electronic equipment, and to avoid cold starting the vehicle. According to Argonne National Laboratory (Argonne), more than 6 billion gallons of diesel and gasoline fuel are wasted by vehicle engine idling—with half from medium- and heavy-duty vehicles alone. Argonne estimated that a heavy-duty long-haul truck generally idles around 6 hours per day, or 1,830 hours per year. Not only does this wasted fuel cost more than $20 billion a year, but it also results in increased emissions of air pollutants, such as oxides of nitrogen, carbon monoxide, and particulate matter. This is particularly an issue for school buses, as these emissions can have harmful health impacts on children. A number of states, counties, and municipalities have implemented vehicle idling restrictions and regulations to address this issue.

Idle reduction technologies afford drivers with the same comforts and services offered by engine idling, but are much more fuel efficient. The U.S. Environmental Protection Agency's (EPA) SmartWay Program and the U.S. Department of Energy (DOE) have evaluated a number of idle reduction technologies for heavy-duty vehicles to identify their fuel reduction benefits. There are two main categories of idle reduction technology: onboard equipment and truck stop electrification (TSE) sites.

Onboard Idle Reduction Equipment
Onboard idle reduction equipment is installed directly on the vehicle. This technology can help reduce idle time at any location, including roadsides, delivery sites, and truck stops. Examples include auxiliary power units (APUs), which are small diesel-powered generators that provide power for temperature control systems and electronic devices, and coolant heaters, which keep the vehicle's engine warm to avoid cold starting. Other technologies include cab or bunk heaters, engine recovery systems, storage air conditioners, and automatic engine stop-start controls. For a complete list and detailed descriptions of available onboard idle reduction equipment, please refer to the Alternative Fuels Data Center (AFDC) Onboard Idle Reduction Equipment for Heavy-Duty Trucks page listed below.

Truck Stop Electrification
TSE sites, also referred to as electrified parking spaces, allow drivers to power temperature control systems and other appliances using equipment provided at the site. Note that TSE can reduce direct vehicle emissions and fuel consumption, although there may be indirect emissions impacts associated with the source of electricity used to power the equipment. There are two types of TSE: single-system electrification and dual-system electrification.

Single-system electrification is comprised of off-board equipment that is stationed at the truck stop. Drivers parked at the site have access to services such as internet, heating, and air conditioning. Dual-system electrification, also known as "shorepower," requires both onboard and off-board equipment because trucks must be able to plug into the external electrical outlets provided. Trucks must have equipment that is compatible with these electrical outlets.

Currently, there are more than 100 TSE sites in operation across the United States, comprising a total of nearly 2,600 parking spaces. For a map of TSE sites, please see the AFDC TSE Locator.

Market Availability Resources
The number of drivers that utilize idle reduction equipment, as well as the portfolio of available technologies, continues to grow. For up-to-date information about available idle reduction technologies for heavy-duty vehicles, see the following resources:
  • EPA's SmartWay Idling Reduction Technologies (IRTs) for Trucks and School Buses:
    • This page includes detailed information about the verification procedure, as well as a list of SmartWay verified idle reduction technologies for trucks and school buses.
  • DOE's National Idling Reduction Network News:
    • Each month, the National Idling Reduction Network releases a newsletter, including information about fleet adoption of idle reduction technologies, new available technologies, funding opportunities, and relevant regulatory news. Check out the September 2016 newsletter for notable news from heavy-duty idle reduction technology manufacturers, including a solar-powered idle reduction system.
  • DOE's Clean Cities IdleBox Toolkit:
    • The IdleBox Toolkit provides outreach materials and educational resources on vehicle idle reduction, including presentations, fact sheets, and other publications specifically for heavy-duty vehicles.
  • North American Council on Freight Efficiency's (NACFE) 2016 Annual Fleet Fuel Study:
    • NACFE conducts an annual survey of Class 8 truck fleets to better understand heavy-duty fleet adoption of idle reduction technologies and practices. Check out the 2016 study, which covers trends in idle reduction technology, based on data collected from 15 North American fleets about their use of 69 different fuel-efficient technologies.
Additional Resources
For more information about heavy-duty vehicle idling and idle reduction technologies, please refer to the following resources:
  • AFDC Heavy-Duty Truck Idle Reduction Technologies:
  • Argonne Reducing Vehicle Idling:

Clean Cities Technical Response Service Team