Most trucks in the United States and many cars around the world have diesel engines. To make these vehicles greener involves replacing their current petrodiesel fuel with biodiesel. It only makes sense, considering that the inventor of the diesel engine, Rudolf Diesel, originally intended for them to run on fuels derived from vegetable oil.

Biodiesel is manufactured using vegetable oil (derived from corn, soybeans, peanuts, and other sources) that has been specially treated. All diesel engines are able to run on a fuel that is part petrodiesel, part biodiesel, as well as 100% biodiesel fuel (although it is known to cause problems in normal diesel engines in cold weather). Some vehicles, however, have special modifications that allow them use 100% pure biodiesel in any weather. It is best to ask the advice of an auto dealer when determining which type of fuel is best for the life of the engine

There are numerous benefits to using biodiesel. It keeps the fuel tank cleaner (this can also be a drawback; see below) as well as being free of fossil fuels. It has great potential as a “homegrown” energy source and therefore as a way to reduce dependence on foreign oil. It is also cleaner than diesel fuel; it produces less toxic chemicals then petrodiesel when burned in an auto engine.

If you spend enough time studying up on fossil fuel alternatives, you will often encounter the phrase “hydrogen economy.” But what is it? And what does it mean for the future of global energy production (not to mention global warming)?

First of all, let’s look at a fuel cell. A fuel cell is something called an “electrochemical energy conversion device.” Basically what this means is that it is a device that converts a fuel, such as hydrogen, into water – releasing heat and energy in the process. The energy is then harnessed as electricity and can be used to, say, power your electric hair dryer. There are many types of fuel cells that can use many different types of fuel sources – including fossil fuels (the waste products are carbon dioxide and water). But hydrogen just happens to be the most abundant substance on earth, and its waste product (water) does not contribute to global warming.

People have been burning garbage for a long time, and until recent technology and new systems became available, it was generally a bad idea. Open-pit trash burning gave way to municipal solid waste incinerators and so-called “waste-to-energy” facilities, but all of them involved the burning of general household, industrial, and even medical garbage – spewing toxic chemicals like dioxins and PCBs into the air.

Biomass gasification and anaerobic digesters are a totally different way of turning waste materials into fuels for energy – and with state-of-the-art pollution control devices, they are almost completely clean and renewable sources of electricity.

One of the many ways to reduce dependence on fossil fuels is to conserve energy. However, it is often difficult for people to build lifestyles of energy efficiency when living in communities whose infrastructures were designed with the assumption that fossil fuels were cheap, inexhaustible, and did not harm the environment. It may therefore be necessary to reshape the infrastructure of automobile-dependent countries such as the United States to help its citizens reduce their carbon footprints.

A fairly unobtrusive way to introduce more energy-smart infrastructure is to set up green building quotas for all new construction. Leadership in Energy and Environmental Design (LEED) is a certification system instituted by the US Green Building Council. It would not be too difficult or pose an undue burden on developers for city and/or state governments around the country to require that a certain percentage of all new construction be LEED certified. Some cities are already doing this. Seattle, for example, has already mandated that all new construction in the city meet green building requirements of at at least a silver LEED certification level.

Harnessing the heat from deep inside the earth is one of the world’s oldest sources of energy. The Romans bathed in spas built around natural hot springs, and Native Americans cooked food and heated their homes with geothermal energy. Now this power source is being tapped for both heat and electricity.

Geothermal energy is used mostly in volcanic regions, where hot magma pools close to the earth’s surface. There are three ways to use geothermal energy. The first is direct usage: heating water by running pipelines close to hot spots in the earth. The second is to tap into underground steam vents; the steam is used to turn the turbines in a power plant. The third is to pump water from an outside source into the ground, where superheated rocks boil the water to generate steam. The steam is then sent to a power plant to turn turbines.

Steam is, of course, generated by boiling water, which is boiled using the combustion of a fuel. Today, those two main fuel sources are coal and nuclear (though there is a growing number of biomass combustion facilities coming on line). Unlike steam-powered turbines, hydroelectric facilities use no fossil fuels. They involve the use of either hydroelectric dams on rivers or tidal facilities on ocean coastlines.

Recent commercials produced by the fossil fuel industry claim that their products are necessary for light and heat. But the light and heat stored by fossil fuels originally came from the Sun. Why not cut out the middle-man and go straight to the source?

Solar energy can be harnessed directly for heating and indirectly for electricity. Passive solar design in architecture and engineering allows the warmth of the Sun to be captured in buildings and water systems, while photovoltaic cells use semiconductors to collect the energy of sunlight and channel it through electrical wires to power light bulbs, machinery, and all other electrical needs.

Passive solar design in architecture allows buildings to trap heat from the sun through a combination of windows and skylights that raise the daytime air temperature, as well as conductive building materials (bricks, masonry, etc.) that store heat during the day and release it slowly throughout the night.

Wind power is one of the best energy alternatives in existence today. Once installed, it is one of the world's cheapest modes of energy production -- the fuel is free! And one of the many other benefits of wind power is that it provides an economic boost to struggling rural communities.

Wind power has come a long way from small-scale production on individual farms. The latest design coming out on the market today is a turbine as tall as a 30-story building that is capable of generating enough power to provide light and heat for up to 600 homes. If such turbines were installed throughout the Midwest, they could potentially provide a percentage of the energy needs of all the lower 48 states. This estimate might sound ambitious, but President Bush recently announced that the country could meet as much as 20% of its energy needs with wind power alone. Wind currently accounts for 0.2% of our energy consumption.

And although the big power companies and municipalities are starting to get serious about large-scale wind production, it still makes a great small-scale community generation project. A mid-sized wind turbine costs about $500,000 to purchase and install, and can power up to 150 homes. Any excess power can also be sold back to the grid as a way of generating revenue for the community. New wind farms also create jobs in rural areas that otherwise have a hard time finding a competitive edge in the economy.