Alternative Fuels

Introduction to Alternative Fuels

Alternative fuels are defined as any material or substance that can be used as a fuel other than convention fuels. The lure of alternative fuel is in finding a source of energy with minimal environmental impacts, provides low cost to the end-user and increases energy security. Many alternative fuels exist, but few are as bountiful, easily produced and cost effective as traditional fossil fuels.

Alternative fuels that are defined by the Energy Policy Act of 1992 include "pure methanol, ethanol, and other alcohols; blends of 85% or more of alcohol with gasoline; natural gas and liquid fuels domestically produced from natural gas; liquefied petroleum gas (propane); coal-derived liquid fuels; hydrogen; electricity; pure biodiesel (B100); fuels, other than alcohol, derived from biological materials; and P-Series fuels."1 However, alternative fuels are actually a broad descriptor of a variety of alternative energy sources. Several fuels are currently under development that may have the benefit of reduced emissions and potentially increase energy security. Those fuels are: biobutanol, biogas, biomass to liquids (BTL), coal to liquids (CTL), Fischer-Tropsch Diesel, gas to liquids (GTL), hydrogenation-Derived Renewable Diesel (HDRD) and Ultra-Low Sulfur Diesel.

Generally speaking, fuels are something that can be consumed to produce energy, and must be gathered and processed before use. There are numerous methods for processing alternative fuels depending on the source used for production. For example, biodiesel is generally an additive or alternative to petroleum based diesel made from animal fats or plant oils. Biodiesel is rendered in such a way that it can be used in a regular diesel burning engine with little or no modification to the engine. In general, liquid or gas-based fuels can be stored and transported similarly to existing petroleum-based fuels, and makes them more realistic for modern day use.

Other fuels, such as hydrogen, must be rendered and used in fuel cells. Fuel cells operate through the constant exchange and movement of chemicals, which in turn produces electricity. This process is not useable in a regular car engine or home heating system, and so requires a substantial investment to install and use in a private entity. Due to being a relatively immature technology, hydrogen cells are still under research and development and are not considered practical for most small-scale uses. Alternative fuels such as hydrogen, ammonia, or electricity are best thought of as tools to store energy until a time when it is more valuable, or to move energy to a place where it is more valuable.


Fischer-Tropsch and No. 2 Diesel fuels

Photo: NREL

Challenges of Alternative Fuels

The use of alternative fuels for power production or conveyance is relatively new. As is typical with most immature technologies, the cost to manufacture alternative fuels is substantially higher than extracting and using fossil fuel sources. Additionally, transportation and storage of alternative fuels can be significantly more difficult and expensive than that of conventional fuels due to their physical attributes. Many alternative fuels exist in solid, or gas, natural states and must either be transformed into a more efficient state, such as a liquid, or require special technology, so it may be consumed or transported. Alternative fuels also typically have lower heating values than fossil fuel, translating into lower energy density. Energy values comparing alternative fuels to conventional fuels can be found in the table below.

Alaska is a large state with a relatively small population that is concentrated primarily in urban centers along the Railbelt. Outside of the Railbelt most communities are sparsely populated and have limited access due to lack of infrastructure. As a result, the creation and distribution of alternative fuels is logistically problematic. Successful projects thus far have operated in small communities with very specific needs (i.e. heat in the winter) who are located off of an established energy grid. While the potential for alternative fuels in Alaska is high, particularly with vast untapped renewable natural resources available at low cost, advancements in technology and infrastructure development is necessary before widespread alternative fuels will become a viable substitute for public consumption.

Fuel Ammonia Biodiesel Dimethyl Ether Hydrogen Propane Gasoline LNG Diesel
Boiling point (ºF) -28 298 -13.8 -423.04 -43.6 100-400 -258.7 355-700
Liquid density @68ºF (kg/m3) 507.86 887 667 490 737 840
Auto-ignition temperature (ºF) 1,204 536-853 455-660 1,050 940 536 1,170 482
Explosion limit (%) 15-28 6-36 3.4-17 4-74 5.5-36 1.2-7.1 5-15 0.6-7.5
Cetane number 48 55-60 5 0-5 0 38-53
Heating Value (MJ/kg) 22.5 37.5 28.84 121.1 46.47 45 50.24 42.7


Alternative Fuels in Alaska


The Palmer Center for Sustainable Living
Photo credit: UAF

Using alternative fuel as a way to increase energy security and lower energy costs in Alaska has become a popular issue. There are currently several alternative fuel projects in Alaska, ranging from waste gas at the Anchorage Municipal Landfill to using fish oil as a feedstock to make biodiesel. Other forms of alternative fuel that are not feasible at this time, such as creating hydrogen through electrolysis using excess energy from renewable generation, are still being research for possible use. Another notable research project is the University of Alaska Fairbanks sponsored Palmer Center for Sustainable Living's work on developing fuels and plastic-like polymers derived from waste wood fibers. This project is very much in the developmental stage, but the effort focuses on addressing not only the replacement of fossil fuels to power vehicles and heat homes, but to also replace petroleum based products such as plastics.

In 2010, Alaska Governor Sean Parnell and the Alaska state legislature expressed desire to see a commercial-scale alternative fuels plant that could convert coal, natural gas, or biomass into liquid fuel using the Fischer-Tropsch process. Ammonia was produced in Alaska until 2007 for fertilizer production using natural gas reformation; however, the plant shut down operations due to the inability to secure long-term access to a natural gas feedstock7. Other alternative fuel developments in the state include vehicle fueling stations, a compressed natural gas (CNG) station in Anchorage and an electric fueling station in Juneau.



Many alternative fuels exist at a viscosity or state of matter (i.e. solid or gas at room temperature, rather than a liquid like traditional gasoline) that is incompatible with existing fuel technology in most vehicles or heating systems. There are many types of alternative fuel technologies that convert or develop existing engines or other energy producing mechanisms to use non-traditional fuels; however, there are a few forms of technology that are frequently required to utilize alternative fuels with existing technology. Before most alternative fuels can be consumed in engines converted for their use, they must be transformed into a more efficient energy state, typically a liquid. The different technologies for transforming non-traditional fuels is listed below.

Biodiesel – Feedstock for producing biodiesel is yellow oil, vegetable oil and tallow. The oils and fats are converted into long-chain mono alkyl esters, commonly know as biodiesel. During production the feedstock is reacted with a short-chain alcohol, typically methanol, in the presence of a catalyst, consisting of sodium hydroxide or potassium hydroxide, to form biodiesel and glycerin8.

Biogas – Biogas is produced from the natural occurrence of anaerobic digestion of diverse organic waste sources. There are multiple sources of biogas generation, however, a large percentage of production is through landfills due to the copious volume of gas that can be accessed. The main methods of anaerobic digestion are dry continuous digestion of source separated waste, farm-scale biogas production and large-scale centralized co-digestion9.

Electrolysis – Using electrolysis, water molecules can be split to produce hydrogen and oxygen molecules. This is done by running an electrical current through the water, creating hydrogen at the cathode and oxygen at the anode10.

Fischer-Tropsch – The Fischer-Tropsch process mixes hydrogen and carbon monoxide produced from the incomplete combustion of a fuel, or gasification, to create syngas, which can be converted into a liquid fuel, such as F-T diesel. Typical feedstocks include biomass, coal and natural gas11.

Haber-Bosch – The Haber-Bosch process pulls nitrogen from the air and fixes it to hydrogen in a reactor to create ammonia. A iron oxide catalyst in a high temperature and pressure environment is used to strip the nitrogen molecules and bind them with hydrogen. This process is generally only 15% effective, although the unfixed elements can be recycled and ran through the reactor again12.

Technology Snapshot

Fischer-Tropsch Fuels Potential to produce liquid fuels at lower cost than petroleum based fuels. Issues include CO2 sequestration, high capital cost, and technology shortage
Propane Based on construction of gas pipeline, Tanana is serving as pilot project
Fish Oil Has been used economically by large fish processors, fish oil from smaller processors could have potential but has been slow to develop
Ethanol and Biodiesel Rapidly evolving technologies with limited feedstock available at this time
Waste Oil Limited resource availability
Hydrogen Expensive to produce and store, pilot studies have not been shown to be economical
Ammonia Requires very cheap electricity and diesel fuel costs above $10/gallon for consideration
Electricity Possibility to use plug-in electric vehicles in areas of the state where the cost of electricity is low

Alternative Fuel Types



Links, Resources, and documents

  • ABS Alaskan - Link to ABS Alaskan, a company that develops and builds alternative energy systems (including alternative fuel systems) specifically for Alaska's environment.
  • Alaska Bus Guy - Link to an Alaskan based bus service run entirely on alternative fuels. A good resource for visitors to Alaska looking to travel green.
  • Grass as Alternative Fuel?: An interesting look at using grass (grassoline) as an alternative fuel.
  • Alaska Natural Resources to Liquids, LLC. "A Legacy Decision for Alaska." June 20,2008. Presentation on Alaska North Slope gas to liquids (GTL) option. Prepared for the Legislative Audit and Budget Committee.

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