Renewable energy can be harvested from various sources using numerous technologies. Nowa Energia Australia focusses on those technologies that have proven to be successful at a large scale, while seeking innovative solutions we believe to have potential for success in Australia. Our focus is primarily in developing wind and solar PV farms with associated infrastructure to ensure reliability and stability of the electricity network.
Wind farms consist of multiple wind turbines, each producing electricity that is collected and transmitted to the electricity network. Wind farms can range from 2 wind turbines generating a total of 6 MW, to 150 turbines producing 450 MW.
Wind turbines produce energy by converting the kinetic energy of the wind into electric energy. In the case of large scale wind farms this is achieved by large three bladed rotors connected to electric generators on the top of tall towers. Energy produced by the generator at 400 volts is then increased in voltage by a series of transformers to be transmitted to the grid by a purpose built substation. Each wind turbine is connected to the substation using underground lines. Usually connection between the substation and the grid is made using overhead lines.
Current onshore wind farms use turbines with rotor diameters around 135m and tower heights between 80 and 150m. The distance between individual turbines is between 350m and 850m.
Among the benefits of a wind farm is its low impact on the current use of the land. Each turbine will only use around 1/3rd of a hectare with 4m wide access roads connecting it to other turbines. Animals can freely graze in the land occupied by the farm and the roads can be accessed and used by the land owners. When correctly designed and sited, there is no adverse impact from noise generated by the turbines on nearby inhabitants; in most circumstances it will not even be noticed.
The most prominent form of solar farms are what is known as Solar Photovoltaic (PV) farms. Solar PV farms use the same technology that has become abundant on the roof tops of Australian homes and businesses, but with the solar panels are mounted on a light steel structures fixed to the ground.
A solar panel is made up of numerous silicon PV cells connected by a lattice of metal conductors. When sunlight hits the PV cells, electrons are released generating direct current (DC). The DC energy from the connected panels are combined, converted to alternating current (AC) by inverters and stepped up in voltage by transformers to be fed into the high voltage transmission grid.
Australia’s abundance of solar energy makes solar PV farms an attractive proposition. Solar PV farms require around 2 hectares of land per Megawatt to install. The land has to be kept free of animals and agriculture and will be fenced off for the safety of animals and humans, as well as the security of the panels.
The benefits of building solar PV farms:
- They have very low visual impact as they are confined to a specified area and rise only a few metres off the ground;
- They have no impact on the environment when in operation;
- They produce energy when the sun is strongest, balancing the significant energy used for cooling in Australia.
The primary drawback of both solar PV and wind farms is that they are not what is known as dispatchable power. That is, they cannot be simply turned on when demand is high. They are only able to produce energy when either the sun is shining, or the wind is blowing. With the increasing generation coming from intermittent sources energy storage is becoming a key focus for regulatory bodies.
Nowa Energia Australia has access to the innovative Water Battery technology that can be combined with wind farms where terrain allows. The Water Battery uses the area around the base of the wind turbine as a water reservoir for pumped hydro energy storage. Each upper reservoir is connected to a lower common reservoir by a water pipe.
Located near the lower reservoir is a small hydro power turbine. Depending on the situation, this turbine works either as a pump or as a generator. At times when the wind farm is producing high amounts of energy and the demand from the grid is low, water is pumped from the lower reservoir up to the towers where it is stored as ‘potential energy’. When demand increases, the water is allowed to fall back down converting its potential energy into kinetic energy which will drive turbine generating electrical energy that can be supplied to the grid.
This innovative technology makes the most of the natural resources available and increases the stability of the grid.
Battery storage technology is improving at a rapid rate. The uptake of electric cars and household battery storage, combined with an increased focus on grid level storage, is leading to cost decreases across the sector. As such, grid scale storage is becoming more and more cost effective. Batteries are able to dispatch power exceptionally quickly, adjusting to increasing demand in a fraction of a second. The rapid response makes it ideal for stabilising the national energy network.