The huge increase in oil and other fuel prices over the last few years and a concern that we have reached (or will soon reach) peak oil – after which oil extraction begins to decrease – have renewed the interest in alternative sources of energy. These include solar, wind, ocean wave and tidal flow, geothermal, and biofuels which at their initial outbreak were considered as the society’s liberator from liquid fossil fuels. However, long disputes regarding the biofuel viability, enriched with high controversy about their actual sustainability, positive and negative effects to the society and so on, have been challenging their acceptance globally from time to time. In general, the alternative energy sources are attractive because they can be developed and used without questioning the very workings of the economic system. Although oil prices may come down as they have since mid-2014 until nowadays, they are likely to return and remain at high levels as the reserves of easily recovered oil and gas relative to annual usage continues to decline. The use of biological materials – coming from recently living plants – as fuels has a long history. Many a night did early humans sit around a wood fire to cook food, keep warm, and protect themselves from predators. Today wood is still used as a fuel source in some countries, dried cow manure is collected in India for that purpose as well, and crop residues in many parts of the world are used for cooking and/or heating. In addition, the natural gas (methane) produced from small-scale liquid manure (animal and human) systems has been used for years in China and India for lighting, heating, and cooking. Moreover, for decades, sewage treatment plants in northern climates have used natural gas produced during the treatment process to heat the vat during the cold seasons, to increase efficiency of the microorganisms in the plant or to produce electricity. The idea behind biofuels is simple. Plants capture the energy of the sun and produce substances – sugars, starch, oils, and cellulose - that can be harvested and then converted into sources of energy for us to use. Growing plants to produce fuel is supposed to be more ecologically sound because – in contrast to diesel oil and gasoline which add new carbon dioxide to the atmosphere when burned – when biofuel energy is used, the carbon dioxide that returns to the atmosphere is simply that which had recently been captured by plants during their lifetime cycle.