NGVs and the Environment

Vehicle emissions contribute to two significant problems facing our country today: urban air pollution and climate change. A change must be made to ensure the health of our communities today and the health of our environment tomorrow. Fortunately, clean-burning natural gas is a proven and increasingly available vehicle fuel that can significantly improve local air quality and reduce greenhouse gases. Read on to learn why natural gas is the right alternative for our health and our environment.

Overview

• Natural gas is the cleanest burning alternative transportation fuel commercially available today.
• Natural gas can reduce greenhouse gas emissions by 20%–30% when compared to diesel and gasoline, according to studies by the California Air Resources Board (CARB) and other organizations.
• Medium- and heavy-duty natural gas engines retrofitted to repower existing fleets were the first engines to satisfy the U.S. Environmental Protection Agency's (EPA’s) demanding 2010 emission standards for nitrogen oxides.
• The light-duty Honda Civic Natural Gas has been awarded the title “Greenest Vehicle” for eight consecutive years by the American Council for An Energy-Efficient Economy (ACEEE).
• Natural gas primarily consists of methane (around 90%), with small amounts of ethane, propane, and other gases. Methane is lighter than air and burns almost completely, creating carbon dioxide and water as byproducts.
• Natural gas rises and disperses quickly, so in the event of a leak or emergency venting, surrounding ecosystems and water systems are not threatened.

Emission Benefits
Here is a look at the emission benefits of a number of natural gas vehicles (NGVs), ranging from light-duty passenger vehicles to heavy-duty fleet vehicles. The charts below provide an easy look at the emission benefits of various NGVs compared to older in-use vehicles and to new diesel or gasoline vehicles.

The oldest production NGV is the Honda Civic Natural Gas (formerly the Civic GX). The compressed natural gas (CNG) powered Civic is recognized by the EPA as the cleanest commercially available internal-combustion vehicle on earth. It is rated by the California Air Resources Board to meet the stringent AT-PZEV standard, and it has also been awarded the title “Greenest Vehicle” for eight consecutive years by the American Council for An Energy-Efficient Economy (ACEEE).

Compared to its gasoline-burning counterpart, the Civic Natural Gas produces 95% fewer emissions of non-methane hydrocarbons and 75% fewer emissions of nitrogen oxides—emissions that contribute to ozone depletion. Most available light-duty NGV models have been certified to meet the Federal Tier 2, Bin 2 standard (only Bin 1, which requires zero emissions, is more demanding).

Honda is not the only company producing low-emission NGVs. Around 50 different manufacturers in the U.S. produce 100 models of light-, medium-, and heavy-duty natural gas vehicles and engines. Many of these manufacturers specialize in replacing fleet vehicles that run on gasoline or diesel—such as school buses, waste collection trucks, and delivery vans—with those that run on CNG. These new CNG fleet vehicles have the greatest emission benefits because they spend much more time on the road than non-fleet vehicles, are more fuel efficient than older fleet vehicles, and generally operate in more densely populated urban areas.

While new natural gas fleets will enjoy the most significant emission reductions, another effective strategy for reducing emissions is to repower or retrofit in-use medium- and heavy-duty vehicles with natural gas engines. These engines have been certified to extremely low levels and were first to satisfy the EPA’s demanding 2010 emission standards for nitrogen oxides.

In the coming years, diesel engine manufacturers are expected to rely on credits as emission standards become more demanding. CNG engine manufacturers, on the other hand, are expected to continue to meet emission standards, and stay ahead of them, as new fuel efficiency strategies are researched and developed.

According to Argonne National Labs, new natural gas vehicles provide the following benefits compared to in-use gasoline and diesel fueled vehicles.

The charts below are based on information prepared for the U.S. Department of Energy and California Energy Commission. The estimates compare new natural gas vehicles with new gasoline and diesel powered vehicles. The emission results include criteria pollutants and greenhouse gas emissions.

Greenhouse Gas Emissions in Greater Detail
Natural gas contains less carbon than any other fossil fuel and thus produces fewer carbon dioxide (CO2) emissions. While NGVs do emit methane, another principle greenhouse gas, the increase in methane emissions is more than offset by a substantial reduction in CO2 emissions. The California Air Resources Board (CARB) has conducted extensive analysis on this issue. It concludes that burning CNG produces about 68 grams of carbon dioxide equivalent emissions per mega joule (MJ) (this includes all methane emissions), and that burning gasoline and diesel fuel produce approximately 94–95 grams of CO2 equivalent emissions per MJ. These comparisons are well documented by CARB and are based on well-to-wheel analysis.

The conclusion of recent studies, such as those conducted by CARB, is that natural gas can reduce greenhouse gas emissions by 20%–30% compared to diesel and gasoline. In the future, these benefits should increase as natural gas supplies are blended with renewable natural gas. Renewable natural gas, commonly referred to as biomethane, is the gas captured from the natural decay of organic materials. Many landfills and waste treatment facilities are beginning to capture biomethane and to incorporate it into the natural gas supply network. Renewable natural gas reduces carbon emissions by almost 90% when compared with diesel and gasoline.

CARB LCFS Carbon Intensity Reductions for Natural Gas:

Additional Benefits
After the Deepwater Horizon oil spill in the gulf of Mexico in 2010, more Americans than ever are concerned about the impact an oil spill could have on our country's environment, health, and economy. There have been enough catastrophic failures in oil's long history to demonstrate that it is not a question of if another spill will occur but when another spill will occur. Natural gas, on the other hand, rises and disperses quickly. In the event of a leak or emergency venting—whether it's at the wellhead or along a distribution line—surrounding ecosystems and water systems are not threatened. Every gasoline gallon equivalent (GGE) of natural gas used as a vehicle fuel is one less gallon of gasoline that would otherwise be brought to market.