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Demand Management

In Australia demand management is a big issue, especially as we try to increase the percentage of renewable energy on our system. In Europe and the US, large energy networks cover tightly connected grids over thousands of kilometres of land. When there is a wind lull or some cloudy sky in one region, the chances are that wind will be blowing 1000 km away, or the sun will be shining somewhere else and energy can be borrowed.

by adding a mix of intermittent energy sources together over geographically spread out areas, energy security and reliability increases

In Australia we simply don't have this option, especially in Western Australia where the grid is relatively small and must stand on its own. Demand management plays a huge role in both reducing the cost of electricity and allowing more wind, solar, wave and geothermal energy onto the grid.

Types of Demand Management

Some of the ways of managing demand include pumping water up a hill to be stored as potential energy. When the energy is needed, electricity is generated by allowing water to displace through a turbine at the bottom of the hill. This is about 60% efficient and requires infrastructure to be placed in a region with adequate hills.

Air Conditioner

Air conditioners can be set to run at different times of the day so that they are not all going flat out during peak load times. Some big buildings even cool ice early in the morning, and then blow air over that ice during the day, thus shifting energy drain from the day time to the night. This smooths out peak demand and increases base load which greatly reduces system cost.

Electric Car

Electric Vehicles and Vehicle to Grid

Electric vehicles or plug in hybrids can store electricity during the night and supply energy to the grid during peak times. Vehicles are stationary 95% of the time, and often in peak times, so why not use their batteries. The cost saving can be passed on to the user and subsidise the electric vehicle industry which will lower the price point of electric vehicles, or EV conversions.

Smart Grid

One of the keys to employing demand management is the introduction of a smart grid. Smart grids can handle a complex array of energy sources and loads from individual household solar panels to large air conditioning systems. They are considered 'smart' as they can manage millions of complex loads and electricity input nodes without disruption to the system. They allow more wind and solar PV to be placed on the system without increasing the risk of power outages.

Power Lines

Smart grids are expensive and take a significant investment, however with a new wave of technology held back from the market currently, the sooner smart grids are implemented, the better.

The starting point for smart grids is the introduction of more more comprehensive metering which can detect energy flow in both directions from the network to the user and vice versa. In addition, smart meters should be able to request energy at a certain price point. Then the user can for example charge up their electric vehicle at night and sell 80% of their battery storage to the grid at peak usage time the next day, and still be able to drive to work and back.

WA Grid (South West Interconnected System SWIS)

Here is a Google Earth overlay of the SWIS network in WA. When designing renewable energy systems, it is important to note where major existing power line infrastructure exists in order to minimise cost associated with designing additional generation.

Source: Western Power