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Wind hybrid power systems combines wind turbines with other storage and/or generation sources. One of the key issues with wind energy is its intermittent nature. This has led to numerous methods of storing energy.
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Wind-hydro system
A wind-hydro system generates electric energy combining wind turbines and pumped storage. The combination has been the subject of long-term discussion, and an experimental plant, which also tested wind turbines, was implemented by Nova Scotia Power at its Wreck Cove hydro electric power site in the late 1970s, but was decommissioned within ten years. Since, no other system has been implemented at a single location as of late 2010.
Wind-hydro stations dedicate all, or a significant portion, of their wind power resources to pumping water into pumped storage reservoirs. These reservoirs are an implementation of grid energy storage.
Advantages
Wind and its generation potential is inherently variable. However, when this energy source is used to pump water into reservoirs at an elevation (the principle behind pumped storage), the potential energy of the water is relatively stable and can be used to generate electrical power by releasing it into a hydropower plant when needed. The combination has been described as particularly suited to islands that are not connected to larger grids.
Proposals
During the 1980s, an installation was proposed in the Netherlands. The IJsselmeer would be used as the reservoir, with wind turbines located on its dike. Feasibility studies have been conducted for installations on the island of Ramea (Newfoundland and Labrador) and on the Lower Brule Indian Reservation (South Dakota).
An installation at Ikaria Island, Greece, had entered the construction phase as of 2010.
The island of El Hierro is where the first world's first wind-hydro power station is expected to be complete. Current TV called this "a blueprint for a sustainable future on planet Earth". It is designed to cover between 80-100% of the island's power and is set to be operational in 2012.
Wind-hydrogen system
One method of storing wind energy is the production of hydrogen through the electrolysis of water. This hydrogen is subsequently used to generate electricity during periods when demand can not be matched by wind alone. The energy in the stored hydrogen can be converted into electrical power through fuel cell technology or a combustion engine linked to an electrical generator.
Successfully storing hydrogen has many issues which need to be overcome, such as embrittlement of the materials used in the power system.
This technology is being developed in many countries and has even seen a recent IPO of an Australian firm called Wind Hydrogen that looks to commercialise this technology in both Australia and the UK. Essentially Wind Hydrogen offers a source of domestic and vehicular energy for rural communities where current energy transmission costs are prohibitive. Test sites include:
Wind-diesel system
A wind-diesel hybrid power system combines diesel generators and wind turbines, usually alongside ancillary equipment such as energy storage, power converters, and various control components, to generate electricity. They are designed to increase capacity and reduce the cost and environmental impact of electrical generation in remote communities and facilities that are not linked to a power grid. Wind-diesel hybrid systems reduce reliance on diesel fuel, which creates pollution and is costly to transport.
History
Wind-diesel generating systems have been under development and trialled in a number of locations during the latter part of the 20th century. A growing number of viable sites have been developed with increased reliability and minimized technical support costs in remote communities.
Technology
The successful integration of wind energy with diesel generating sets relies on complex controls to ensure correct sharing of intermittent wind energy and controllable diesel generation to meet the demand of the usually variable load. The common measure of performance for wind diesel systems is Wind Penetration which is the ratio between Wind Power and Total Power delivered, e.g. 60% wind penetration implies that 60% of the system power comes from the wind. Wind Penetration figures can be either peak or long term. Sites such as Mawson Station, Antarctica, as well as Coral Bay and Bremer Bay in Australia have peak wind penetrations of around 90%. Technical solutions to the varying wind output include controlling wind output using variable speed wind turbines (e.g. Enercon, Denham, Western Australia), controlling demand such as the heating load (e.g. Mawson), storing energy in a flywheel (e.g. Powercorp, Coral Bay). Some installations are now being converted to wind hydrogen systems such as on Ramea in Canada which is due for completion in 2010.
Communities using wind-diesel hybrids
The following is a, probably incomplete, list of isolated communities utilizing commercial Wind-Diesel hybrid systems with a significant proportion of the energy being derived from wind.
Wind-diesel hybrids at mining sites
Recently, in Northern Canada wind-diesel hybrid power systems were built by the mining industry. In remote locations in Lac de Gras and Katinniq, Ungava Peninsula, Nunavik two systems are used to save fuel at mines. There is another system in Argentina.
Wind-compressed air systems
At power stations that use compressed air energy storage (CAES), electrical energy is used to compress air and store it in underground facilities such as caverns or abandoned mines. During later periods of high electrical demand, the air is released to power turbines, generally using supplemental natural gas. Power stations that make significant use of CAES are operational in McIntosh, Alabama, Germany, and Japan. System disadvantages include some energy losses in the CAES process; also, the need for supplemental use of fossil fuels such as natural gas means that these systems do not completely make use of renewable energy.
The Iowa Stored Energy Park, projected to begin commercial operation in 2015, will use wind farms in Iowa as an energy source in conjunction with CAES.
Wind-solar building
The Pearl River Tower in Guangzhou, China, will mix solar panel on its windows and several wind turbines at different stories of its structure, allowing this tower to be energy positive.
Wind-solar lighting
In several parts of China, there are lighting pylons with combinations of solar panels and wind-turbines at their top. This allows space already used for lighting to be used more efficiently with two complementary energy productions units. Most common models use horizontal axis wind-turbines, but now models are appearing with vertical axis wind-turbines, using a helicoidal shaped, twisted-Savonius system.