Renewable energyVS.

Fossil energy

Viaenergetiki

What is renewable energy?

• An energy sources that can be used instead of fossil fuels.

• It is usually a renewable source of energy that could be used if fossil fuels run out.

Why is there need for renewable energy? (I)

• 90 per cent of the worlds energy come from fossil fuels.

• Fossil fuels are convenient and relatively cheap.• Because they are fossil fuels they DO have a life

expectancy.• Oil has left for 40-50 years, but it was said

already in 1960 – what has happened is that we have found new reserves of oil and new technology has made the oil we use last longer.

Why is there need for renewable energy? (II)

• Burning fossil fuels has increased atmosphere pollution.

• Vehicle exhausts contribute to acid raid more so than power stations burning coal.

• The carbon stored in fossil fuels is released as carbon dioxide when thay are burnt – this leads the green house effect and global warming.

Fossil fuels

• Term used to describe a variety of energy sources which do not have a finite supply.

• In contrast, energy sources such as coal, oil and gas are non-renewable forms of energy and will one day run out.

• Traditional fuels have negative environmental impact caused by CO2 emissions

Wind

• Generating electricity from wind is pretty straight forward – basically, electricity is produced when wind blows a massive turbine that spins to create the electricity.

• Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.

Solar energy

• Solar energy is one of the most easily available renewable sources of energy. This can be harnessed from the sunlight received by the earth and used for electricity generation, running cars, cooking food and numerous other chores in our daily life.

Geothermal energy• Geothermal energy is energy obtained by tapping the heat of the earth

itself, both from kilometers deep into the Earth's crust in some places of the globe or from some meters in geothermal heat pump in all the places of the planet . It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth's core.

• Three types of power plants are used to generate power from geothermal energy: – Dry steam plants take steam out of fractures in the ground and use it to

directly drive a turbine that spins a generator. – Flash plants take hot water, usually at temperatures over 200 °C, out of the

ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine.

– In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine.

Hidropower

• Another widely used source of renewable energy, hydropower is harnessed by using the flow of water to move turbines to create electricity.

• Water has been used for quite some time to make electricity, but died out a bit when fossil fuels became more popular.

Bioenergy• Liquid biofuel is usually either bioalcohol such as bioethanol or an

oil such as biodiesel.• Bioethanol is an alcohol made by fermenting the sugar

components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions

• Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.

Renewable energyVS.

Fossil energy

Viaenergetiki