Renewable energy is energy that is naturally replenished from resources which include sunlight, wind, rain, wave, tides, and geothermal heat. Oil, coal and gas are fossil fuels which produce carbon dioxide (CO2), a greenhouse gas which is widely believed to contribute to global warming. About 21.3 billion tones of CO2 are produced each year through the burning of fossil fuels. Carbon Dioxide and other gases keep the Earth habitable by naturally trapping solar heat in the atmosphere. However, Earth’s natural processes can only absorb roughly half this amount, leaving a net increase of 10.65 billion tonnes of atmospheric carbon dioxide each year. According to most scientists, this causes Global Warming, which is a term to describe the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century.
The industrial revolution of the 18th and 19th centuries saw a significant increase in CO2 levels in the atmosphere. Before this period, levels were between 260 and 280 parts per million (ppm); now, human activities have increased this to roughly 380 ppm, an increase of thirty-four per cent. The world is evolving at an unforseen rate, and climate change is become one of the biggest worldwide agendas. Earth's temperature has risen by around 0.7°C over the past 100 years, and is projected to increase by 1.0°C - 6.4°C over the next ninety years. Ice caps have lost 40% of their thickness over the past forty years, causing sea levels to rise at a rate of 1.8mm per year between 1961 and 2003. This rate increased to 3.1mm in the ten years to 2003. By 2100, levels are expected to rise by 18-59cms from now, with the possibility of a 100cm rise not out of the question if glaciers and ice sheets continue to melt at an alarming rate.
Mean surface temperature change for the period 2000 to 2009 relative to the average temperatures from 1951 to 1980
The use of fossil fuels creates other by-products which are pollutants, and include sulphur dioxide, soot and ash, which change the properties of clouds. These by-products absorb solar energy and reflect sunlight back into space, thus meaning that less reaches Earth’s surface. This phenomenon is called Global Dimming, and was first publicly coined by an English scientist, Gerry Stanhill, in Israel. When published in 2001, his research was met with sceptical responses from other scientists; it was not until Australian scientists confirmed the findings that global dimming became an issue. It is probable that the environmental issue will mask the affect of global warming—especially during the day—however, the increase in cloud caused by the dimming process will trap heat during the night, acting as a sort of blanket.
Despite Australia being very susceptible to the impacts of climate change—and seeing profound environmental effects during recent decades—just 4% of its energy in 2006 came from renewable sources. It does, however, want to increase this to 20% by 2020, and under former Labor Prime Minister Kevin Rudd, Australia committed to reducing carbon emissions to at least 60% below their 2000 levels by 2050. As the world’s population continues to grow, energy consumption is also increasing, and along with the environmental impact of fossil fuels, they take millions of years to replace, therefore meaning that we need to find an alternate form of energy—the obvious solution is increased use of renewable energy.
In developed countries such as Australia, a significant increase in renewable energy is practical. Instead of looking at the ground for our energy needs, we should turn out attention to the sky, where if captured through solar energy, the sun produces enough energy every hour to power the world for a year. Solar energy is harnessed light and heat from the sun, and there are two different methods used to produce solar energy. One is Photovoltaic, which are cells that are converted to direct current electricity. Photovoltaic is extremely reliable and can be expected to live up to 25 years. The second is solar thermal (or heat) energy, which uses mirrors reflected onto thermal collectors, which is then used to heat. However, as with other renewable sources, the main drawback to solar is cost. Solar thermal energy is currently two times the cost of gas fired generation, and Photovoltaic’s are up to four times more expensive. Also, to work at their most efficient level, solar panels need to be cleaned regularly. The Australian Government offer rebates on some solar systems, while Aurora energy, a Tasmanian Government-owned electricity distribution and retail company, offer a buy back on solar power connected to the grid in the state.
In contrast to the rest of Australia, the country’s smallest state, Tasmania, generates up to 91% of its energy from renewable hydro and wind power—giving the island state a clean, green image. The other 9% is from four gas-fired power stations which produces about 830,000 megawatt hours of electricity. This non-renewable source is used because a lack of rain affects (meaning dams are low) affects the amount of hydro-electricity produced, and wind power is not always reliable because the right conditions are needed for power to be generated. Still, the state’s greenhouse gas emissions are low, producing less than 0.05 tonnes of greenhouse gases per megawatt hour of electricity generated in 2009—18 times less than the Australian state average. Tasmania is home to two operating wind farms and twenty-nine hydro-electricity power plants in seven different catchment areas.
Wind turbines work by turning blades of large windmills which then generates electricity. Although wind power in Tasmania produces 480,000 megawatt hours (notably less than even gas), it is expensive, costing $70 per megawatt hour to produce—significantly higher than the $35 per megawatt hour for a coal-fired plant, and $40 per megawatt hour for a gas-fired plant. Tasmanian wind farms are located on the north-west coast (Woolnorth Wind Farm) and King Island (Huxley Hill Wind Farm), while another is currently being constructed at a cost of $400 million at Musselroe Bay in Tasmania’s north-east. The Woolnorth Wind Farm is owned by Roaring 40s, and has 62 wind turbines which has a generating capacity of 140 megawatts. A three stage project, Woolnorth was fully completed in May 2007, and is considered one of the best wind farms in the world.
Hydro-electricity was the first form of renewable energy to be used in the state, when the Duck Reach Power Station was opened on the South Esk River in Launceston during 1895. It provided the city with electricity, and was the first publicly owned hydro-electric plant in the Southern Hemisphere. Hydro-electricity is created when gravitational potential energy from water initially stored in lakes or dams, is turned into kinetic energy when it flows through the pipes and into the power station which is connected to a generator that makes electricity. Hydro is much more reliable then solar, wind or wave power, but is much more expensive to build, and sites for the construction of hydro dams are difficult to find. The Great Lake in the Midlands (Australia’s largest natural freshwater lake), and Lake Gordon in the south-west of Tasmania, contain more than 80% of the water storage for the state’s 29 power stations.
Tasmania’s eagerness for hydro-electricity has, however, seen one of the world’s rare inland beaches destroyed. Lake Pedder was previously a natural lake, located in the south-west of the state, and in the warmer months when water levels were lower, Pedder revealed a pink quartzite beach, which took ten minutes to walk across. Though, in 1972, three dam walls were built around Lake Pedder, thus trapping the flows of both the Serpentine River and the Huon River. This caused a giant lake impoundment to be formed, so as to top up the larger Lake Gordon (situated nearby), where the power station is located. At the expense of generating capacity, alternatives were suggested to this development, even by the Federal Government, but Tasmanian leaders did no bow to opposition of their Gordon River Power Scheme. The demise of the original Lake Pedder may have helped stimulate public outcry that eventually stopped the damming of the Gordon River. Set to be called the Franklin Dam, the Tasmanian Government proposed a hydro-electricity dam capable of generating 180 megawatts, but after significant protest, Australian Prime Minister, Bob Hawke, tried to stop the proposal, resulting in a legal battle between the Federal and Tasmanian Government. The High Court ruled in favour of Bob Hawke’s Government in 1982, and the development was stopped.
Along with wind, hydro and solar energy, there are two other main forms of renewable energy—Geothermal and Biomass. Geothermal is steam from the ground which then turns turbines and then produces electricity. There are two different types of geothermal energy: one is when the earth supplies steam from the ground, the second is pockets of heat below the surface that can be used to heat water into steam. In either case, they both turn turbines to make electricity. Biomass energy, also called bioenergy, is energy that is produced from plants, wood, wood sludge and plant materials. There are numerous ways to produce Biomass energy: Methane gas (e.g. from landfills and sewage treatment plants), Dry agricultural products (e.g. sugar cane wastes), Municipal mixed wastes (e.g. Houses hold garbage and pruning’s), Forestry products (e.g. remnants from sawmills and forestry operations).
Although Tasmania is Australia’s coolest state (with Hobart averaging 8-17°C and Launceston 7-18°C), global warming has seen the state have an increase of 0.8-1.0 over the past fifty years—in line with the rest of the country. Rainfall has also declined up to 20mm per decade in the north-west and south-east, while increasing by between 5-15mm per decade in notoriously wet parts of the south-west. A detailed report by the CSIRO, Hydro Tasmania and Tasmanian Partnership for Advanced Computing, indicates that annual rainfall in the west and central areas is set to increase by 7 to 11%; decrease by around 8 % in the north-east; and increased winter and early spring rainfall for the entire state by 2040. Temperatures are expected to increase by 0.33%, with warmer minimum temperatures in winter and late spring and early summer throughout the state. The study also found that sea levels around the state will rise by between 20 and 60cm by 2095. As we see an increase in wind-powered energy in Tasmania, the amount of wind produced in the state is important. However, speeds are only expected to increase marginally—with the biggest increases in winter, early spring, early summer, and particularly in the north-west in late autumn.
These affects could be devastating for the state, as it’s strongly export related—exporting 9.3 million tonnes of freight to mainland Australai, and 8.7 million tonnes overseas. These manufacturing industries that supply our exports, use significant amounts of energy—and with and emissions trading scheme, electricity prices will increase, causing problems in this sector where Tasmanian industries have little capacity to pass on costs to customers because of the competitive international markets in which they supply. Agriculture is likely to be affected as some crops may no longer be suitable to grow in certain areas, but may become viable in other regions. The increasing water temperatures may cause fisheries to be affected the most out of all industries. These changing conditions are expected to affect aquaculture production—especially Atlantic salmon—and Tasmanian fish species may migrate to areas where water temperatures are cooler. Positive implications, nonetheless, may mean that warmer water fish species migrate further south to waters surrounding Tasmania.
Research indicates that the best two renewable sources for Tasmania are hydro-electricity and wind—our two current forms of energy. However, many households are beginning to be fitted with solar panels, thus harnessing energy from the sun. But because Tasmania has low sun intensity in the cooler months, not much energy is produced during these months.
Before construction of the Woolnorth Wind Farm, research was undertaken to see if the area was the windiest in the state, results found the location on the north-west coast to be as such, and was therefore constructed there. Its location is in the path of prevailing westerly winds, and the farm produces energy in air that a nearby air monitoring station records as the cleanest in the world. In 2002, a monitoring tower was built to determine the wind potential of a proposed wind farm site at Musselroe in north-east Tasmania. Results were encouraging, and the farm was given the all-clear for construction. These areas are obviously the best locations for wind turbines in the state—far better than calmer places in more inland areas and the south-east.
Hydro-electricity dams—Tasmania’s biggest source of energy—are located or connected to high rainfall locations on the western side of Tasmania, as eastern Tasmania has significantly less rainfall. Although the construction of Musselroe will see more wind energy produced, Hydro will remain the state’s largest source of energy for a long time to come, because of the amount of rainfall western Tasmania receives, and the number of hydro-electricity power stations already constructed and works efficiently. Research by Choice Magazine stated that it could take up to 45 years for solar panels to pay for themselves in Tasmania, so solar panel introduction into Tasmanian homes is not as viable as other locations in Australia. Tasmania’s population is not expected to grow as much as the rest of Australia’s, and only reach 550,000 in 2050 before declining, therefore meaning it does not need to produce a great deal more electricity than it currently does. Global Warming, however, might mean that the usual climatic conditions in the state might change over time and hydro-electric dams might have to move to locations better suiting future weather conditions. In summary, hydro, wind and solar are all suitable forms of energy for the state, but solar would not have a big capacity in the cooler months. For the best amount of wind energy to be produced, wind farms would have to be located on the coasts where they are today. Fortunately, Tasmania is already in a good place with its renewable energy production, it is the Australian mainland that has a long way to go.