Energy Efficient Future Technologies

Table of Contents

New Solar Cells
Geothermal Energy
Wave Energy
Electrical Storage
Solar Tower

New Solar Cells

Steady improvements in house design will reduce the energy running costs. A new thin solar panel called Sliver which is designed in South Australia and which uses 1/20th the amount of silicon compared to regular solar panels while still achieving 20% efficiency. It can be used on glass and looks like tinting. Other thin film solar can be placed in the flat sections of roofing iron. By using building surfaces to collect solar energy it also reduces heat entering the building by around 20%. Newer manufacturing techniques that are a variation on printing technology use fewer materials so should bring the cost of solar power down. A desirable end goal for this technology would be $1 US per watt produced. This would level the playing field with other fossil energy sources.

Suggestions: Occasionally review new technologies that might suit your house or building and calculate the possible savings.

References for further information 8 104 105 106 116

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Geothermal Energy

Geothermal energy technology using hot dry rocks (HDR) has been piloted to produce steam at over 220 degrees Celsius by pumping water down 3-5 kilometres for heating and then under its own pressure back to the surface. Two or more bores have to be drilled. A small 1 MW thermal power plant based in South Australia is scheduled for completion in 2008. If this proves to be economically viable, then sources of base load power that is carbon neutral will be available 24 hours a day. A smaller variation on this theme is the geothermal 80 kW generator in Birdsville Australia. It uses naturally hot (98 degrees Celsius) groundwater which is run through a heat exchanger at 27 litres per second to boil and expand isopentane which runs the thermal generator. The groundwater is then used for the town's purposes.

The largest geothermal energy from volcanic sources is in California at 750 MW using 350 wells in a 78 km2 area. Over 70 countries use this type of energy including Iceland, New Zealand, China and Hungary. This energy can be used for heating and the generation of electricity.

References for further information 107 108

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Wave Energy

A submersible pump that captures power produced by the action of waves of a floating buoy going up and down 1-2 metres. This creates pressure which is fed into a hydro style turbine on land. The first pilot of this system is in Fremantle, West Australia. It is estimated that a 1 metre high wave front can generate 20 kW per metre width. As most of the Australian population lives on or near the coast, the transmission losses to the load are minimal. An additional significant benefit is that the pressurised water can also be used for direct desalination using osmosis, without the electrical consumption of other desalination systems. One option that could be useful is to use the system for electrical generation during the day peak electrical load and then to produce desalinated water at night.

Another system is to use the wave pitch with floating metal cylinders containing hydraulics and generators inside. These can be arranged in joined lengths with electrical connections from each cylinder fed back to land.

Tidal power can be used for electrical generation by using submersible turbines connected to a structure fixed to the sea floor. A 1.2 MW version with two 16 m turbines with connected on a crossbeam is being used around the UK and Ireland.

Suggestions: First perform an audit of the wave and tidal energy first by using meteorological information to predict ahead of time the likely generated output.

References for further information 109 110 111

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Electrical Storage

Some of the current disadvantages of battery technology include a recharging lifespan, slow charging, high weight and cost. A high voltage variation of a capacitor, an electronic component that holds a charge and is made from ceramics, may solve all the battery issues. The company EeStor is trying to develop a capacitor that can operate at 3500 volts with the energy stored being proportional to voltage squared. The end result would be a battery with 3 times the energy density of the current favourite lithium ion with a 5 minute charge time. The Zenn Motor Company owns the rights to use this battery and expects to release a car using this battery by 2009. They expect a car with 400 km range with a maximum speed of 120 km/h. Other uses of this type of battery are for remote solar power storage. These capacitors have a recharge cycle life that is measured in millions therefore you may never have to swap a battery again. Another possible use for this type of battery is to supply energy back into the grid at peak periods from near the load. This would reduce the stress on current electrical transmission systems and of peaking power stations.

Suggestions: Look out for Electrical Energy Storage Unit (EESU) or large Ultracapacitors

Related Sections: Electric Car Remote Solar

References for further information 112 113

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Solar Tower

This type of energy generation works on the principle that hot air rises. Air has a 1 degree Celsius drop per 100 metres rise. The generator shape is similar to a large fairly flat upside down funnel. Solar energy hits the funnel and heats the air underneath. This air wants to rise and heads up towards the spout section were it meets wind turbines. The air then rises up the funnel. The principles are simple compared to the actual construction. A proposed 200 MW $800 M design for Mildura in Australia would require a 1 km tower and 5 kilometre diameter of heating area with 32 x 6.5 MW turbines adjacent to the tower. Wind speeds of 15 metres per second are expected. Heat collecting tubing underneath the collector could improve the power supply to 24 hours a day. A 50 MW prototype of this technology was built in Spain with a 600 foot tower, with an 800 foot diameter collection area. The main difficulty is in the creating a 1 km high structure. Perhaps when this civil engineering is mastered the price per tower will reduce. No water is required to run this technology.

Suggestions: Perhaps having smaller versions of this technology available may make it more attractive.

Related Sections: Large Turbine Wind Energy Solar Thermal Power

References for further information 115

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