Transcript Renewable energy

Renewable energy
VS.
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 dieselpowered vehicles. Biodiesel is produced from oils or fats using
transesterification and is the most common biofuel in Europe.
Renewable energy
VS.
Fossil energy
Viaenergetiki