Background – The 1/3^rd Peak Lopping Principle

The Northern Territory Power andWater Corporation (PWC), as part of its investment assessment procedures, considers possibilities for renewable energy generation where commercially appropriate.

PWC has been an industry leader in remote-area power developments, and its Jilkminggan demonstration site (Figure 1) for solar technology has confirmed that, by adding around 30 per cent of photovoltaic (PV) generation capacity, peak demand on a diesel system is reduced. The Northern Territory is in a unique situation, in that the peak power demand closely matches the availability of the solar power over the course of a day, with the peak occurring early afternoon (see Figure 2). Instead of running a large diesel set at low load (e.g. 40 per cent), a smaller diesel set can be run at optimal load (e.g. 75 to 90 per cent) as the solar provides the peak load. Battery storage is not required, since the diesel engines meet the gap between the actual demand and the power provided by the solar system. The economic and environmental savings from this arrangement are significant.

Savings

With the assistance of significant grants from the Australian Greenhouse Office and the Northern Territory Department of Business, Industry & Resource Development (under the Renewable Energy Commercialisation Program and the Renewable Remote Power Generation Program), the NT solar PV project aims to demonstrate the commercial viability of peak lopping using an optimal mix of solar and diesel technology. The resultant hybrid system will reduce diesel fuel usage, reduce operation and maintenance costs and provide benefits by reducing greenhouse gas emissions.

PWC will seek to replicate the concept in other locations in the Northern Territory, including remote communities, Aboriginal outstations and some mining sites, and in isolated diesel-fuelled sites in South-East Asia. As an indication of the economic and environmental significance of the scheme, similar installations at all remote Territory diesel power stations could save $1.75 million in diesel fuel and over 7,100 tonnes in CO₂ emission annually (over 1 per cent of PWC’s annual emissions from electricity generation).

To date, this has been the most cost-effective proposal for renewable energy in this location and has economic, technological and social benefits for Power and Water and the Northern Territory. The NT Solar PV project will provide employment and increase the knowledge base in the renewable energy industry.