What is Renewable Energy

With the Earth’s supply of fossil fuels perpetually declining, new and exciting energy systems are being designed to exploit sustainable resources.

Each year the global population is increasing at an exponential rate, creating a ravenous demand for energy. Fossil fuels cannot sustain this and it is forcing governments across the globe to re-evaluate how they are going to provide power for future generations.

Luckily, right now numerous systems are being designed and developed worldwide to address this issue, demonstrating novel and creative methods of exploiting the renewable resources with which the Earth is blessed.

Harnessing the power of sunlight, wind, rain, tides and geothermal heat, these technologies are slowly repositioning the balance of power away from finite resources and towards sustainable ones, mitigating long-held fears over a world post-oil and delivering power generation on a domestic as well as industrial level. Let’s take a closer look at some of the most promising solutions out there.

Solar furnaceSolar furnace

Generating power from sunlight – The Odeillo-Font-Romeu solar power station in the Eastern Pyrenees, France. Positioned in front of the reflector (out of view here) is an array of 63 flat orientating mirrors that automatically track the motion of the Sun, reflecting incident radiation onto the parabolic reflector mirror. The reflector consists of 9,500 mirrors that concentrate the Sun’s rays onto a dark-coated furnace at its focus (central tower). The system is capable of producing thermal power of 1,000 kilowatts, and achieving a temperature of 3,800 degrees Celsius within the furnace.

How Pelamis Wave Energy Converter Work

The Pelamis Wave Energy Converter from Pelamis Wave Power is a system designed to generate renewable electricity from ocean waves. The system consists of a semi-submerged, articulated structure (180 metres long and four metres in diameter) consisting of cylindrical sections linked by joints. These joints, under the pressure of wave-induced motion, move and are resisted by hydraulic rams, which pump high-pressure fluid through hydraulic motors to drive electrical generators and produce electricity. This energy is then fed from each joint down an umbilical and then carried back to shore in a single large seabed feed. Each Pelamis Converter is rated at 750kW and on average a unit will produce 25-40 per cent of that rating annually, which is the annual electricity demand for roughly 500 homes.

How SeaGen tidal generator Work

SeaGen tidal generatorThe SeaGen tidal generator from Marine Current Systems is an operational – albeit prototype – tidal system based in Strangford Narrows, Northern Ireland. The system consists of twin 16-metre in diameter, submerged axial-flow rotors, which are attached to a central machine and control tower that is fixed to the seabed. Both rotors on the SeaGen sport a unique feature that allows the blades to be pitched through 180 degrees, allowing them to operate in both tidal directions. Appearing like an upside-down submerged windmill, SeaGen works by converting high velocity currents into usable electricity throughout the tidal cycle -much like how a windmill utilizes the power of the wind to rotate its sails. Indeed, its large-scale rotors – aided by the 400 million gallons of water that flow past it twice a day – can develop a rated power of 1.2 MW at a current velocity of 2.4m/s. This gives SeaGen the ability to deliver about 10 MW per tide, which annually amounts to 6,000 MWh of energy.

How geothermal power plant works

Geothermal energy is power extracted from heat stored inside the Earth. The heat is generated from radioactive decay, volcanic activity, core convection and solar energy absorbed at the Earth’s surface. Geothermal power plants work by pumping water down a borehole into hotspots a few kilometres beneath the Earth, then forcing it out of a second borehole into a steam turbine to produce electricity.

Solar updraft towers

Solar updraft towersAn elegant system to exploit solar energy, the solar updraft tower works by combining the chimney effect – where cold air is drawn upwards by reduced local pressure – the greenhouse effect and a wind turbine.

The power plant works by trapping air heated by the Sun under a large greenhouse-like circular membrane, which, through convection and the chimney effect, causes the hot air to be sucked in towards and up the central tower. As the hot air travels up the tower the airflow drives a selection of turbines that in turn produce electricity. Definitely one to watch in the future…