How are wind microgenerators used to capture energy ?

Two main types of system can be utilised:

1. Stand-Alone Systems

Domestic turbines are often used in stand-alone power systems that are designed to charge a battery bank. The most common application for this set up is in cases where a grid connection is not an option due to a prohibitive cost or remote location.

2. Grid-connected Systems

In this type of system, the output of the wind turbine is connected to the existing mains electricity supply to the home via a controller and inverter. Excess electricity generated can be sent onto the grid while electricity can be drawn from the grid when the turbine is not producing enough electricity to meet your needs. ESB Customer Supply offers to domestic microgenerators a 9c/kWh payment for exported electricity. Electric Ireland is offering to all domestic electricity customers of all suppliers a further 10c/kWh for the first 3,000 kWh export in each year. This offer is open to the first 4,000 customers who qualify and is due to close in 2012.

A third arrangement employed by some users of small turbines is to heat water directly from the turbine and not connect the turbine to the electricity supply to the premises or to the grid. The energy can then be stored as heat to be used on demand if the storage capacity is sufficient and very well insulated. 

what is microgeneration ?

What is microgeneration?

Around the world the definition of microgeneration can vary. Microgeneration is classified by ESB Networks as grid connected electricity generation up to a maximum rating of 11kW when connected to the three phase grid (400V). The vast majority of domestic and agricultural customers are connected at single phase (230V) and for these customers to be classified as microgenerators the maximum rating permitted is 6kW. These ratings are in line with Irish conditions prescribed in European standard EN50438.

In Ireland customers with microgenerators can avail of a stream lined, one page connection process (using form NC6)  Customers who exceed the classification must engage in a more demanding application and connection process. However ESB Networks intend to make the connection process for units up to 50kW less onerous than the process required for larger generators.

A microgenerator may use any one of the following technologies to generate electricity:

• Wind turbine
• Photovoltaic panels (also known as solar electric panels)
• Micro-hydro (scaled down version of hydro-electricity station)
• Micro-CHP (fuelled by bio or fossil fuels)

Two or more of the technologies may be combined to create a hybrid system. Domestic and small commercial wind microgeneration involves using a small-scale wind turbine system to harness energy from the wind. In general it is at its most competitive and cost effective in remote, exposed areas or for charging batteries on boats, caravans and holiday cabins i.e. where grid connection might be too expensive or impractical.

With the use of an electrical control panel and an inverter the electricity generated can be used to supply electricity to the home, the amount of which depends on the size of the turbine installed, the demand at any given time and of course the wind available. An inverter is necessary for a number of reasons. One of its functions is to convert direct current (DC) to alternating current (AC) which is the type of power utensils and appliances demand i.e. 'mains' electricity. Direct current is outputted by the controller which is in turn supplied with power from the turbine. The inverter is also necessary to synchronise the output of the turbine with the electricity being drawn from the grid to ensure the occupant sees no interruption in their supply.