26 Can you explain the difference between biofuels and fossil fuels? BIOENERGY What is bioenergy? The word bioenergy refers to renewable forms of energy such as: biomass and biofuels; syngas; The gases which make up syngas are primarily hydrogen and carbon monoxide that often also contains some amount of carbon dioxide and methane. For example, to obtain high quantities of biomass, huge forests should be cut down and the processes to get geothermal energy involve fractures which may damage the soil. ONLINE RESOURCES Biore neries and ENI by-product: prodotto di scarto to cleanse: purificare core: nucleo to lower: abbassare rapeseed: colza soy: soia sugarcane: canna da zucchero 70 ELECTRICITY geothermal energy. Biomass and biofuels Biomass consists of living or recently dead organisms, plants, or animals, and of their by-products which can be used in the production of energy or heat. To produce electricity, biomass is burned in a boiler; this generates heat, which produces high pressure steam. This steam flows over a turbine, causing it to rotate. The rotation of the turbine drives a generator that produces electricity. The steam in excess is condensed back into water, which is re-used in the same process to produce steam. Biomass is also used to produce biofuels in an attempt to substitute fossil fuels and lower greenhouse gas emissions . At present, the most commonly used biofuels are ethanol, produced from corn and sugarcane, and biodiesel, obtained from soy, rapeseed, and palm oil. Geothermal energy Geothermal energy exploits the natural heat underneath the Earth s surface. Heat is generated in the Earth s core by continuous chemical and nuclear reactions. Geothermal energy can be obtained in three different ways: taking steam directly from fractures in the ground to drive a turbine which starts a generator; pumping cold water down under the Earth s surface to create steam that is used to drive a turbine connected to a generator; using hot water passed through another fluid that has a lower boiling point than water: the heat turns the secondary fluid into vapour and this drives a turbine. Pros and cons As they are renewable, energy sources such as biomass and geothermal are not at risk of running out. Moreover, they are always available, abundant, and contribute to the reduction of waste. However, exploiting these energy sources requires expensive procedures; they have a high impact on the environment and, in addition, biomass burning releases a certain amount of greenhouse gas. Syngas Syngas is a highly combustible mixture of gases produced from waste materials and other biomass. As it Heat exchanger contains some carbon dioxide and other harmful substances, syngas must be cleansed before being used. Syngas is used in the same way as biomass for the production of electricity. Turbine/generator Power