Archived Outdoors

Green energy

Over the next few weeks in The Naturalist’s Corner, I’m going to be exploring different aspects of the alternative and green energy movement.

Alternative fuel types

Alternative fuels noted by the Energy Policy Act of 1992 include electricity, ethanol, propane, natural gas, hydrogen, biodiesel, methanol and p-series fuels. Below is a short overview of each of these fuels.


The main fuel source for producing electricity is coal. Other sources are nuclear, natural gas and hydroelectric. Batteries, which can be large and bulky, must be replaced every three to six years. Most electric vehicles (EVs) only have a range of 50 to 120 miles before they must be recharged.

Electricity is also used in hybrid (electric-gasoline) vehicles. These vehicles combine a gasoline and electric engine. There is no need to recharge the batteries in a hybrid as they recharge themselves from the gasoline engine. The battery power is used in low speed (40 m.p.h. or less) situations and the gasoline kicks in above 40 m.p.h.

EVs have no tailpipe emissions. With hybrids it depends on which engine you are using. Service requirements for EVs are assumed to be less since there are fewer moving parts — no oil changes, radiator service, etc. The same can’t be said for hybrids.


The primary fuel sources for ethanol include corn, other grains and agricultural waste. Ethanol is a high octane (100) fuel. Ethanol is generally blended with gasoline. The two most common blends are E10 (10 percent ethanol) and E85 (85 percent ethanol). E10 will run in any gasoline engine while E85 requires a flex-fuel engine.

Related Items

E85 engines produce 25 percent fewer ozone-forming emissions than conventional gasoline, but the whole carbon footprint issue is debatable because of the fossil fuels required to grow crops like corn.

Some special engine lubricants may be required but for the most part engine service and maintenance are comparable to current gasoline engines.

Ethanol is produced domestically, it is renewable and availability is rapidly expanding across the U.S.


Propane or liquefied petroleum gas (LPG) is a petroleum by-product. Conversion kits are required but almost all vehicles can be converted. There is a 60 percent reduction in greenhouse emissions when compared to conventional gasoline engines.

LPG is one of the most widely available alternatives in the U.S., however 45 percent of LPG produced in the U.S. is produced from oil.

LPG is more flammable than gasoline so adequate ventilation is required when fueling. LPG tanks are 20 times more puncture resistant than gasoline tanks and regarded as just as safe as conventional gasoline tanks.

Natural gas

Natural gas (LNG) is another type of fossil fuel found in underground reservoirs. Today only a few heavy-duty trucks and buses use LNG for fuel and conversion is required. Ozone emissions are reduced, however HC (hydro-carbon) emissions may be increased.

LNG is a cryogenic fuel — a liquefied gas kept liquid at very low temperatures. They require special handling and equipment and high-pressure tanks require periodic inspection and certification.

There are only 35 public LNG stations in the U.S., although it is available through the purveyors of cryogenic liquids.


Hydrogen fuel is produced from natural gas, methanol and other sources like nuclear energy and coal. Currently hydrogen is four times as expensive to produce as gasoline. But hydrogen fuel cells are popular with the current administration and money has been set aside for research to lessen that gap.

There are no commercial hydrogen vehicles today but some prototypes are being leased for demonstration purposes. A hydrogen engine would release no ozone emissions but nitrogen oxides (NOx) would be present.

Maintenance for hydrogen fuel cell vehicles should be minimal. But much more research and development will be required before hydrogen becomes a viable option.


Biodiesel may be made from almost any type of vegetable oil, including soy, palm, animal fats and even recycled cooking oil. And can even be made at home.

Like ethanol, biodiesel is blended for the most part. B20 is probably the most common blend there are many advocates calling for B100 or 100 percent biodiesel. Most of today’s diesel engines will run on B20 without modification. Biodiesel is becoming more available across the country. Ozone emissions are less than conventional diesel but NOx may be increased.


Methanol may be made from natural gas, coal or biomass. Some heavy-duty buses use methanol today. M85 reduces ozone emissions by 40 percent compared to gasoline engines. However, combustion of methanol may release formaldehyde.

Methanol can be produced domestically from renewable resources. Engines need special lubricants and some conversion for M85. Methanol can form explosive vapors in fuel tanks, but in accidents it is actually less dangerous than gasoline because of its slow evaporation, which keeps alcohol concentrations in the air low.

Methanol is not commonly used today.


A relative newcomer to the alternative mix is P-Series fuel, a blend of natural gas liquids, ethanol methyltetrahydrofuran (MeTHF). P-series fuels are designed to run in any flex-fuel vehicle (FFV). They are 70 percent renewable and cut ozone emissions compared to conventional gasoline engines.

P-series fuels are new and as such not, presently, widely produced but do hold potential according to many proponents.

Next week we will talk about the philosophy, economy and politics of alternative fuels, and after that go into greater detail about the more prominent alternative fuels out there.

Leave a comment

Smokey Mountain News Logo
Go to top
Payment Information


At our inception 20 years ago, we chose to be different. Unlike other news organizations, we made the decision to provide in-depth, regional reporting free to anyone who wanted access to it. We don’t plan to change that model. Support from our readers will help us maintain and strengthen the editorial independence that is crucial to our mission to help make Western North Carolina a better place to call home. If you are able, please support The Smoky Mountain News.

The Smoky Mountain News is a wholly private corporation. Reader contributions support the journalistic mission of SMN to remain independent. Your support of SMN does not constitute a charitable donation. If you have a question about contributing to SMN, please contact us.