Micro Generation –Wind turbines

What is Micro Generation?

If the renewable energy system you intend to install (or already have) is having capacity;

• Less than 5.75 kw if single phase which means the maximum current is 25A (amperes)

or,

• Less than 11 kw if Three Phase and maximum current per phase is 16A

the ESB Networks of Ireland classifies them as Micro Generation systems.

What Systems are included?

Micro Generation covers;

• Wind Turbines-
• Photo Voltaic Cell ( also known as PV) arrays
• Mini Hydro Power
• Micro Combined Heat and Power Units- These are strictly not operated on renewable energy. But due to their very high fuel efficiencies and as some operate on Biomass fuel are included as Micro Generation systems.

Wind Turbines for Domestic use

Wind turbines in domestic use could be any of the following types;

• Grid Tied Wind Electric Systems with Battery back-up
• Battery less Grid Tied wind Electric systems
• Direct drive , battery less wind electric systems

Grid Tied System

A grid tied system is a system where the renewable energy generated power is connected to the utility grid. This connection will serve to tap the power from the mains grid when the renewable energy generation is slack or export power back to the grid when the generation is surplus. In a micro generation system both the up load or down load will be low voltage single phase or three phase power.

What is a Grid Tied System with battery back up?

The battery back up serves to store the generated renewable energy power so that in case of a power outage in the grid mains the stored energy will be released to maintain a steady supply to the household. This is similar to the Uninterruptible Power supply (UPS) in a large system such as a server installation. The difference is that in a micro generation system the surplus power would be exported to the grid and imported only when the renewable energy is not adequate.

The battery back up type wind turbine system is a better option for catering for power outages than solar back up systems in that most of the power break downs occur due to complication of high winds. The major draw back is that this is the most expensive wind electric system you can have. Naturally the maintenance expenditure of both the turbine and the battery bank would constitute a part of the overall operating costs.

Battery less Grid Tied wind electric systems

This is the most cost effective and environmentally friendly wind turbine power generating system you will have. Elimination of batteries also eliminates the associated initial cost, cost of maintenance, cost of disposal of unserviceable and some times paying an efficiency penalty.

The only draw back will be that you will be totally without any power when the wind flow is slack and there is a power outage as well. As you know in these modern times total power outages of long durations in the mains utility grid is rare. It therefore is a small price to pay for the low investment and environmental benefits.

Battery less wind systems may provide more efficient power generation than a system with batter back-up. The reason for this is that the inverter electronics of the battery less system can match the wind's loads finer and regulate the turbine's rotational speed for optimized power generation.

Direct drive, battery less wind turbine systems

This is the least common of all the wind electric systems. The Wind turbine drives a piece of equipment such as a water pump with the generated electricity. The turbine is matched to the pump through an electronic controller. The operation of the pump will only be when the wind flow is adequate. In the right situation this could be most cost effective and simplest system. Another application is space heating which is a good match as it s cold when it is windy. But to be effective to cater for the high thermal load the turbines have to be fairly larger than for pumping.

Wind turbines if installed with professional help can benefit homes in the right locations. It is not the best home renewable energy system in terms of maintenance, capital cost and simplicity. In certain remote locations you may not have any other option left. The out put of wind turbines when the wind flow is reduced is little. Making your home a bit energy efficient will make even this reduced out put adequate for certain homes. An off grid system can also have a small gas, bio fuel or fossil fuel type generator for back up in poor winds.