Renewable Energy Powers Energy-efficient School

by the CADDET Australian National Team

Introduction

Marshmead, a school campus at an isolated location within the Croajingalong National Park in the State of Victoria, Australia was established by the Methodist Ladies College, Melbourne. The site is 114 hectares of partly cleared land which was once used as a farm. The property had no mains power connection due to the prohibitive costs and environmental hazards involved with running transmission lines through many kilometres of fragile and fire-sensitive woodlands. The school shows how the use of passive solar design features and a remote area power supply (RAPS) system can be used successfully for an educational facility in an isolated location.

Design

The overall design of the campus is based on a pedestrian village. About 90 people live there during the school term. The student accommodation consists of three student clusters, each with three houses. Central facilities and two staff residences complete the southern area of the village. To the west are the residences for the director, deputy director, and other staff along with the workshop, dairy, pump house, resource centre, gear shed and bunkhouse. The rural campus enables the students to spend a single period of eight weeks at the farm to learn about, as well as experience, an energy efficient and environmentally conscious lifestyle in a residential community.

Power System

The power system at Marshmead was originally designed to produce 120 kWh of power per day. The RAPS system is made up of a number of elements:

  • 2.5 kW photovoltaic system;
  • 10 kW three-phase wind turbine;
  • 80 kVA three-phase Perkins diesel generator;
  • three 10 kVA inverters;
  • control system to regulate the system;
  • meters for students to monitor power loads;
  • 35 kVA three-phase stand-by diesel generator.

Power is provided to four commercial washing machines (3 kW each), dishwasher (1.9 kW), coolroom (2 kW), freezer (1.3 kW) and two under-bench refrigerators.
 The wind and solar elements in the system reliably provide the base electrical load during the day; however, the 80 kVA diesel equipment is usually required during the night, when there is a heavy drain on the batteries.
 The buildings are constructed using many passive solar design features such as:

  • insulated external walls, floor and ceiling;
  • thermal mass provided by mud-brick internal walls;
  • main glass areas facing north providing good solar access with shading;
  • cross-ventilation with doors on the south;
  • two separate zoning areas - living areas and bedrooms.

Economics

Early estimates by the project consultants put the cost of supplying overhead lines to the site at about $120,000 and underground power at approximately $200,000 (where $ is the Australian dollar).
 Under the conditions at Marshmead, the wind and solar equipment produces an average of 14 kWh/day, saving over 5,000 kWh/year of diesel-produced energy.
 The annual diesel fuel consumption for electricity generation is about 25,000 litres. Therefore, the wind and solar system not only saves about 10% of the diesel fuel, but the generator operates for shorter times leading to reduced maintenance costs.
 The development could only proceed under the strict control and guidelines of the Department of Conservation and Natural Resources so that the delicate environment could be preserved. Marshmead is an excellent example of thoroughness in design of the energy efficient features of the buildings and a RAPS system that could easily be used for other building types in isolated locations such as tourist facilities and roadhouses.
For more information contact the Australian National Team in Canberra.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors. They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to
Pauline Toole, Editor, CADDET Centre for Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44 1235 432968, Fax: +44 1235 433595.