Renewable Energy

Fergus Aitchison

Renewable energy

• Energy derived from resources that are regenerative

• Currently accounts for ca. 14% of the worlds energy consumption

• Dose not produce as many greenhouse gases as other forms of electric generation

• Involve natural phenomena

• Wind• Water• Sunlight• Geothermal heat

Wind Energy

• Wind energy is a relatively young but rapidly expanding industry

• Over the past decade, global installed capacity has increased from:

2500MW (1992) -> 40000MW (2003)

Annual growth rate of 30%

• Projected that wind will achieve 75000MW in EU by 2010

• This would represent overall contribution of electric supply of 5.5%

• By 2020, this figure expected to increase to more than 12%

– Providing the demand of 195million European household consumers

Design • Tubular towers are made of steel and taper from their base to the top

• Rotor blades are typically manufactured from glass polyester of glass epoxy, sometimes in combination with wood and carbon

• The rotors of modern wind turbines generally consist of 3 blades

• A modern power generating wind turbine is designed to:

– Generate high quality, network frequency electricity

– Operate continuously, unattended and with low maintenance for over 20 years

20 Years = 120000 hours

• Car engine is designed for 4000-6000hours of continuous running

The Wind Resource

• The single most important characteristic is the wind speed

• Doubling of average wind speed, would result in the power in the wind increasing by a factor of 8

• If the average wind speed at a given site increases from 6m/s to 10m/s, the amount of energy produced by a wind farm will increase by 130%

• It is therefore vital in the development of a wind farm to provide detailed and reliable information about how strongly and from which direction the wind blows.

Exploiting the wind resource• In the last 20 years wind power generation costs

have declined by some 80 percent

• From units of 20-60 kW in the early 1980s, with rotor diameters of around 20m, generators of single wind turbines have increased to 5,000 kW, with rotor diameters of over 100 m

• Some prototype designs for offshore turbines have even larger generators and rotors.

• The dramatic increase in size and technological know how, coupled with economy of scale from fast growing production volumes have greatly reduced the cost of wind power

• Wind turbines are highly reliable, they are able to run during 98% of the hours in a year. No other electricity generating technology has a higher availability.

• A growing market for offshore wind power is now the main driver for the development of large turbines

• Wind farms are operating off the coasts of Denmark, Sweden, Ireland, the Netherlands and the United Kingdom

• Although there are still many challenges, including costs for both grid connection and foundations, there are major advantages in the higher mean wind speeds, low turbulence (i.e. longer turbine lifetime) and reduced constraints to be found offshore

• A resource large enough to supply all of Europe’s electricity.

• A number of constraints affect the site. These include – land ownership, – positioning in relation to roads or overhead lines, – the location of inhabited buildings such as schools and homes– avoidance of sites of special environmental importance.

• Once these constraints have been determined, the layout of the wind turbines themselves can be planned.

• The overall aim is to maximise electricity production whilst – minimising infrastructure,– operation and maintenance (O&M) costs,– and socio-environmental impacts.

• Once operating, a wind farm can be monitored and controlled remotely

Hydroelectric

Water Power

• Main forms of water power– Hydroelectric– Wave– Tidal

Hydroelectric

• Uses the energy of flowing water, without depleting it, to produce electricity

• Supplies about 19% of the world electricity

• World leading form of renewable energy, accounting for 63%

Process

• Flowing water…

• Turns a turbine….

• Which turns a generator……producing electricity

Advantages

• Can produce over 200 times more energy from an installation than the energy needed to build and run the installation. This is ten times more than oil fired power stations - and with minimal atmospheric pollution.

• A modern hydro turbine generator set can convert over 90% of the energy in the available water into electricity.

• Electricity generated from hydropower can be placed on the grid faster than any other energy source.

• Hydropower reservoirs collect rainwater, which can then be used for drinking or irrigation. By storing water, they protect aquifers from depletion and reduce our vulnerability to floods and droughts.

• River water is a domestic resource and, unlike fuel or natural gas, it is not subject to market fluctuations

• The life-cycle of hydropower produces very small amounts of greenhouse gases. Hydropower currently avoids burning 4.4 million barrels of oil equivalent daily, worldwide.

• Hydropower plants produce no air pollutants. Very often, they replace fossil-fired generation, thereby reducing acid rain and smog. Moreover, hydropower projects do not generate any toxic by-products.

• Flexibility and storage capacity make it the most efficient and cost-effective way to support the deployment of intermittent supplies such as wind or solar power.

• Facilities with reservoirs offer unique operational flexibility in that they can respond immediately to fluctuating demand for electricity.

• With an average life span of 50 to 100 years, hydropower projects are long-term investments that can benefit several generations.

Solar

• In half an hour enough of the sun's energy reaches the Earth's surface to meet the World's energy demand for a year.

• The sun produces 400,000,000,000,000,000,000,000,000 watts of power. That's 400 x 1012 TW.

• The World's average energy consumption is around 14 TW!

• Just one square cm of the Sun's surface burns with the brightness of 232,500 candles.

• All the Earth's oil, coal and wood supplies would fuel the Sun for only a few days.

Solar Thermal Electricity

• produce electric power by converting the sun`s energy into high-temperature heat using various mirror configurations

• Is then channelled to an on-site power plant and used to make electricity through traditional heat-conversion technologies.

• The plant essentially consists of two parts: one that collects solar energy and converts it to heat, and another that converts the heat energy to electricity.

Solar thermal power plant

• Southern Spain• A concrete tower - 40 storeys high • The rays of sunlight reflected by a field of 600 huge

mirrors (each 120 sq m in size) • Europe's first commercially operating power station using

the Sun's energy this way • It generates 11 Megawatts (MW) of electricity without

emitting a single puff of greenhouse gas. • This current figure is enough to power up to 6,000

homes. • But ultimately, the entire plant should generate as much

power as is used by the 600,000 people of Seville

• It works by focusing the reflected rays on one location, turning water into steam and then blasting it into turbines to generate power.

• What happens when the Sun goes down? Enough heat can be stored in the form of steam to allow generation after dark - only for an hour now but maybe longer in future.

• power is three times more expensive than power from conventional sources

• but prices will fall, as they have with wind power, as the technologies develop.

• 1. The solar tower is 115m (377ft) tall and surrounded by 600 steel reflectors (heliostats). They track the sun and direct its rays to a heat exchanger (receiver) at the top of the tower

• 2. The receiver converts concentrated solar energy from the heliostats into steam

• 3. Steam is stored in tanks and used to drive turbines that will produce enough electricity for up to 6,000 homes