Renewable energy is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat.
Renewable energy resources exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency is resulting in significant energy security, climate change mitigation, and economic benefits.
The EU's Renewable energy directive sets a binding target of 20% final energy consumption from renewable sources by 2020. To achieve this, EU countries have committed to reaching their own national renewables targets. Greece has set a target of 20% energy from renewable sources in gross final consumption of energy in 2020 (National Action plan). To achieve it, the share of renewable energy in electricity was set at 40% (20% in heating and cooling and 10% in transport).
They are also each required to have at least 10% of their transport fuels come from renewable sources by 2020.
Renewables will continue to play a key role in helping the EU meet its energy needs beyond 2020. EU countries have already agreed on a new renewable energy target of at least 27% of final energy consumption in the EU as a whole by 2030 as part of the EU's energy and climate goals for 2030.
Solar energy is the most abundant energy resource on earth -- 173,000 terawatts of solar energy strikes the Earth continuously. That's more than 10,000 times the world's total energy use. Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.
Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV), indirectly using concentrated solar power, or a combination. Concentrated solar power systems use lenses or mirrors and tracking systems to convert the sun’s energy into high-temperature heat. The heat is then channeled through a conventional generator. A solar cell, or photovoltaic cell (PV), is a device that converts light into electric current using the photovoltaic effect (photons from the sunlight are absorbed by the cell, which creates an electric field across the layers and causes electricity to flow).
The first silicon solar cell, the precursor of all solar-powered devices, was built by Bell Laboratories in 1954.
Development of solar power in Greece started in 2006 and installations of photovoltaic systems skyrocketed from 2009 to 2013 because of the appealing feed-in tariffs introduced and the corresponding regulations for domestic applications of rooftop solar PV. Because that boom in the market couldn't be sustained, since August 2012, new regulations have been introduced including retrospective feed-in tariffs reduction, with further reductions over time.
A new RES law (L.4414/2016) voted in August 2016 introduced a new policy framework which abandoned the feed-in tariff (FIT) policy in favour of a feed-in premium scheme for systems over 500 kWp.
In January 2017, the total installed photovoltaic capacity in Greece had reached 2,611 MWp from which 545 MWp (21%) were installed on rooftops and the rest were ground mounted.
Wind power is the use of air flow through wind turbines to mechanically power generators for electric power. Wind power, as an alternative to burning fossil fuels, is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions during operation, consumes no water, and uses little land. The net effects on the environment are far less problematic than those of nonrenewable power sources.
Wind farms consist of many individual wind turbines which are connected to the electric power transmission network.
Wind turbines use blades to collect the wind’s kinetic energy. Wind flows over the blades creating lift (similar to the effect on airplane wings), which causes the blades to turn. The blades are connected to a drive shaft that turns an electric generator, which produces the electricity.
Greece has an extremely rich wind potential, especially in the regions of Crete, Peloponnese, Evia and of course of the Aegean islands, and started exploiting it in the 2000s. Wind power capacity has expanded rapidly in Greece and at the end of 2016, the total installed wind capacity in Greece had reached 2,374.3 MW.
The increased commissioning of wind power is being accompanied by record low prices for forthcoming renewable electric power. In some cases, wind onshore is already one of the cheapest electric power generation option and costs are continuing to decline.
Biomass is any organic material that has stored sunlight in the form of chemical energy. Wood is a well-known example of biomass: it can be burned for heat or shaped into building materials. There are many additional types of biomass that can be used to derive fuels, chemicals, and power—such as plants, agricultural and forestry residues, organic components of garbage (municipal solid waste), and algae.
Burning biomass releases carbon emissions, but has been classed as a renewable energy source in the EU and UN legal frameworks, because plant stocks can be replaced with new growth. As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel.
At present in Greece, biomass is principally employed for the generation of heat at home (eg, for cooking and heating), for heating greenhouses, at oil mills and, using more advanced technologies, in industry, but on a limited scale. The use of biomass for the production of biofuels as well as for the generation of electricity is limited (60 MW of total installed capacity in 2017), but with the potential for growth.
Geothermal energy is heat energy generated and stored in the Earth. Earth's internal heat is thermal energy generated from radioactive decay and continual heat loss from Earth's formation. Geothermal power is cost-effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries.
There are three main types of geothermal energy systems:
- Direct use and district heating systems
- Electricity generation power plants
- Geothermal heat pumps
Direct use and district heating systems use hot water from springs or reservoirs located near the surface of the earth.
Geothermal electric stations use the high temperature hydrothermal resources that come from either dry steam wells or from hot water wells near the surface to produce electricity. The hot water or steam powers a turbine that generates electricity.
Geothermal heat pumps use the constant temperatures near the surface of the earth to heat and cool buildings. Geothermal heat pumps transfer heat from the ground (or water) into buildings during the winter and reverse the process in the summer.
Greece is not yet using its geothermal potential, especially the volcanic arc of the South Aegean (Milos, Nisyros, Santorini) for electricity generation.
Hydropower is power that derives from the energy of falling water or fast running water, which may be harnessed for useful purposes. Since ancient times, hydropower (from watermills) has been used as a renewable energy source for irrigation and the operation of various mechanical devices. In the late 19th century, hydropower became a source for generating electricity.
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. A large pipe (the "penstock") delivers water from the reservoir to the turbine.
The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The hydro station consumes no water, unlike coal or gas plants.
According to the Greek Electricity Market Operator (LAGIE), the total large hydro-power installed capacity in the Greek interconnected system at the end of 2016 reached 3,173 MW (19% of the total installed capacity in the Greek interconnected system).
As of December 2016, there has been an installed capacity of 223 MW of small hydro-power (SHP) plants in Greece. By definition, these are hydro-power stations with a capacity less than 15 MW. As all SHP plants are of the run-of-river type, most of their generation takes place during the wet season (winter and spring). There are 105 SHP projects in operation, mostly located in Epirus, Macedonia and Peloponnese.
Oceans cover more than 70% of the Earth's surface. As the world's largest solar collectors, oceans contain thermal energy from the sun and produce mechanical energy from tides and waves.
Marine and hydrokinetic technologies capture energy from oceans and rivers—including waves, tides, ocean currents, free-flowing rivers, streams, and ocean thermal gradients—to generate electricity. These technologies are at a very early stage of development.