Archive for the ‘cogeneration’ Category

How plummeting PV prices will greatly change the electricity distribution network

Tuesday, July 14th, 2009

I attended a workshop today in Melbourne run by iGrid, a consortium of universities and the CSIRO preparing a model of the intelligent energy grid of the future.

Its been identified that peak demand, which is rising faster than electricity consumption, is one of the most critical issues that a distributed generation network can address.

Dr. Muriel Watt, Chair of the Australian Photovoltaic Association and Project Manager with IT Power gave a presentation about the future pricing of PV, with  similar themes touched on by Michael Williamson from Sustainability Victoria.

Solar PV prices have historically decreased by roughly 20% for every doubling of global production. At current growth trends this means that the cost of PV generated electricity in Australia is likely to reach grid parity within the next five to ten years. “Grid parity” meaning that the cost of generating electricity from a PV system will be equal to the cost of buying electricity off the grid. This assumes some government support.

The $8,000 government rebate for a 1kW system has resulted in around 100,000 Australian households now having PV systems. As prices continue to lower it will become economic for business to also install PV.

As prices approach grid parity and take up of PV systems grows strongly we should see a significant reduction in greenhouse gas emissions. Most of these systems will be grid connect. Along with the uptake of other technologies, such as small scale co-generation, the electrical distribution grid will be transformed from one that provides for a one way flow of energy to one in which two way flows are experienced.

This in itself will generate other challenges, such as the need for energy storage in the grid. Several presenters discussed electric cars as a storage solution. Most cars are in use for less than two hours a day, and the rest of the day, if the appropriate infrastructure exists, could provide storage capacity to the electrical network.

There will need to be significant investment into the electricity distribution network to make it smart. Regulatory changes will be needed to facilitate this.

The upcoming “smart meter” rollout in Victoria, set to start over the next few months, is just one step in this direction. The distribution network itself needs to get smarter (so for example voltages can be adjusted), and the information collected by the smart meters should be made available to customers to result in a more effective demand side response, particularly if time of use pricing is introduced. There is opportunity for innovative new products to use this data to shift loads and influence consumer behaviour.

Cogeneration Opportunities in Leisure Centres

Monday, February 23rd, 2009

Leisure centres are notorious for their high green house gas emissions. These facilities use energy for water heating, filtration, air heating, air handling, lighting, air conditioning, and gym equipment, to name the main loads. To maintain the strict chemistry requirements of the pool water and to avoid corrosion brought about by moisture laden air, several of these systems operate 24/7.

These characteristics often make a compelling economic case for onsite power generation through cogeneration. The perfect candidate for cogeneration is a leisure centre that has an indoor all year round heated pool, with an air handling system, and a base load of above 30kW. Below this magic mark, the cost associated with installation reduces the appeal of the investment.

Most Australian leisure centres use both natural gas and electricity, supplied through utility providers. Recently we have seen a growing interest in cogeneration from leisure centres that realise large greenhouse gas savings can be achieved, with reasonable pay back periods of 5 – 10 years.

Cogeneration is the process of converting combustible fuel into electricity and usable heat. This can be done in a variety of ways depending on the requirements of the facility. A cogeneration system is made up of the following:

cogeneration schematic

Prime mover


Heat recovery system

Control system

Picture modified from

In leisure centres the most suitable style of prime mover is a gas fired micro turbine, or an internal combustion engine. To size the optimal cogeneration system a numerical model is designed which considers the sites heat and electricity load profiles, electricity and gas associated cost parameters, and the market available technologies.

In conventional power generation 35% of the combusted fuel is converted into usable electricity, while the other 65% is lost as heat. A further 5 – 10% of this electricity then disappears through transmission. By producing electricity onsite with a cogeneration plant, the heat needn’t be wasted but rather put to work in heating operations, and in some cases it can be used for cooling when coupled with an absorption Chiller. By using the waste heat, the efficiency of the system increases up to 90%, and because the power is generated on site, transmission losses are kept to a minimum.

Cogeneration’s fast pay back and large greenhouse savings, situate it as an important short to medium term technology for carbon reductions. The current drawback is that the system does rely on natural gas which is not renewable, so its long term feasibility may rely on the development of grid connected bio fuels or reliable carbon offsets.