Renewable Energy

Bus versus Aircraft

{ 11:32 AM, 6/5/2008 } { 0 comments } { Link }

Travelling by bus is the most environmentally conscious way of travel. Greyhound buses in Australia are some of the most environmentally efficient travel operators. Studies have shown that one full coach has five times less CO2 emissions per passenger per kilometre than a jet aircraft on the same route, and for every full coach, there are 16 fewer cars on the road. The buses are also fuelled with the cleanest diesel on the Australian Market, BP 10PPM. I will take as example a trip from Melbourne to Sydney considering that the bus uses 1 litre of diesel per 4 km. The distamce is 900km so the bus is using 900 / 4 = 225 liters of diesel. With 60 people on the bus one person is using 3.75 litres of diesel per trip.

Sunset on Mars

{ 3:05 PM, 14/3/2008 } { 0 comments } { Link }

Sunset on Mars

Picture from NASA taken by Mars Exploration Rover Spirit.

Biodiesel Production

{ 1:00 PM, 9/12/2007 } { 1 comments } { Link }

Current biodiesel production capacity in Australia is about 18 million litres per year, however plans for establishment of new facilities or expansion of existing ones will increase this capacity to around 90 million litres per year. For example in Wyong NSW, Australian Biodiesel Consultancy and Collex are currently operating a trial biodiesel plant, using recycled cooking oil and tallow that produces 15 million litres per year. In WA, Australian Renewable Fuels has a plant which produces 40 million litres of biodiesel per year. It uses low grade tallow and used cooking oils as feedstock and will also annually produce 6,000 tonnes of raw glycerine and 1,800 tonnes of sulphate of potash fertiliser in paste form. It is using an improved production technology called a Continuous Trans Esterification Reactor (CTER) that reduces processing time and can reduce plant capital costs by up to 50%.

Strathfield Library

{ 2:45 PM, 2/9/2007 } { 1 comments } { Link }

Strathfield Library is powered by solar energy and is approximately producing 2000W by 12 noon as it is shown on the photo belo. This library is located in Strathfield, Sydney, Australia and the monitor is showing the power being generated. This library is aiming for an eco friendly future.

Emmisions Trading

{ 12:20 PM, 3/6/2007 } { 1 comments } { Link }

Emissions trading (or cap and trade) is an administrative approach used to control pollution by providing economic incentives for achieving reductions in the emission of pollutants all over the world. In such a plan, a central authority (usually a government agency) sets a limit or cap on the amount of a pollutant that can be emitted. Companies or other groups that emit the pollutant are given credits or allowances which represent the right to emit a specific amount. The total amount of credits cannot exceed the cap, limiting total emissions to that level. Companies that pollute beyond their allowances must buy credits from those who pollute less than their allowances or face heavy penalties. This transfer is referred to as a trade. In effect, the buyer is being fined for polluting, while the seller is being rewarded for having reduced emissions. Thus companies that can easily reduce emissions will do so and those for which it is harder will buy credits which reduces greenhouse gasses at the lowest possible cost to society. There are currently several trading systems in place with the largest being the European Union's. The carbon market makes up the bulk of these and is growing in popularity. Many businesses have welcomed emissions trading as the best way to mitigate (prevent) climate change. Enforcement of the caps is a problem, but unlike traditional regulation, emissions trading markets can be easier to enforce because the government overseeing the market does not need to regulate specific practices of each pollution source. However, monitoring (or estimating) and verifing of actual emissions is still required, which can be costly. Critics doubt whether these trading schemes can work as there may be too many credits given by the government, such as in the first phase of the European Union's scheme. Once a large surplus was discovered the price for credits bottomed out and effectively collapsed, with no noticeable reduction of emissions.

Agricultural biofuels

{ 10:20 AM, 12/5/2007 } { 0 comments } { Link }

The word biofuel comes from the word biomass (recently living organisms or their metabolic byproducts such as manure from cows). This is a renewable energy source, unlike other natural resources such as petroleum, coal, and nuclear fuels. Like coal and petroleum, biomass is a form of stored solar energy. The energy of the sun is captured through the process of photosynthesis in growing plants.

Agricultural products specifically grown for use as biofuels include corn and soybeans (mainly in the United States), flaxseed and rapeseed (mainly in Europe) sugar cane in Brazil, palm oil in South-East Asia and jatropha (not an agricultural product) in India. Biodegradable outputs from industry, agriculture, forestry and households can be used like straw, timber, manure, rice husks, sewage, biodegradable waste, and food leftovers. These can be converted to a biogas through anaerobic digestion. Biomass used as fuel often consists of underutilized types, like chaff and animal waste. The quality of timber or grassy biomass does not have a direct impact on its value as an energy-source.

Unlike other forms of renewable energy, biofuels do not reduce the amount of greenhouse gases in the atmosphere. Burning biofuel produces carbon dioxide and other greenhouse gases. The carbon in biofuels was recently extracted from atmospheric carbon dioxide by growing plants, so burning it does not result in a net increase of carbon dioxide in the Earth's atmosphere. Therefore, many people believe that a way to reduce the amount of carbon dioxide released into the atmosphere is to use biofuels to replace non-renewable sources of energy. Simply Biofuels do not reduce greenhouse gases when they have become a fuel, instead when it was alive (as a plant or animal) it had reduced the amount of grenhouse gases. Also it does not emit any greenhouse gases, except when it is being made. Yet the amount of gas emitted is still lower than how much the living thing reduced. Dried compressed peat is also sometimes considered a biofuel. However, it does not meet the criteria of being a renewable biofuel. Though more recent than petroleum or coal, on the time scale of human industrialisation, peat is a fossil fuel and burning it does contribute to atmospheric CO2.

Much research is being done about the use of microalgae as an energy source, with applications for biodiesel, ethanol, methanol, methane, and even hydrogen. Use of hemp is increasing, but politics restrain it. In some industrialized countries like Germany, food is cheaper than fuel compared by price per joule, mostly because fuel is taxed more than food. Central heating units supplied by food-grade wheat or maize are available. The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter (usually cellulose, agricultural and sewage waste) in the efficient production of liquid and gas biofuels which yield high net energy gain. One advantage of biofuel over most other fuel types is that it is biodegradable, and so relatively harmless to the environment if spilled.

Water Energy

{ 11:08 AM, 18/4/2007 } { 1 comments } { Link }

Energy in water (in the form of motive energy or temperature differences) can be harnessed and used in various ways. Since water is approximately a thousand times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.

There are many forms of water energy:

Hydroelectric Energy

A term that usually reffers to hydroelectric dams.

Tidal power

Which captures energy from the tides in a vertical direction. Tides come in, raises water levels in a basin, and then the tides roll out. Around low tide, the water in the basin is discharged through a turbine.

Tidal stream power

Which captures energy from the flow of tides, usually using underwater plants resembling a small wind turbine.

Wave power

This Water Power uses the energy in waves. The waves will usually make large pontoons go up and down in the water, leaving an area with reduced wave height in the "shadow".

Ocean thermal energy conversion (OTEC)

This uses the temperature difference between the warmer surface of the ocean and the colder lower recesses. To this end, it employs a cyclic heat engine.

Deep lake water cooling

Although this is not technically an energy generation method it can save a lot of energy in summer. It uses submerged pipes as a heat sink for climate control systems. Lake-bottom water is a year-round local constant of about 4 °C.

Blue energy

Blue energy is the reverse of desalination. A difference in salt concentration exists between seawater and river water. This gradient can be utilized to generate electricity by separating positive and negative ions by ion-specific membranes. Brackish water is then produced. This form of energy is in research and costs are not the issue. The tests on pollution of the membrane are in progress. At this moment it is predicted that if everything works out, 33% of the electricity needs in the Netherlands could be covered with this system (this source is from 2005).

Renewable Energy

{ 9:24 AM, 18/4/2007 } { 1 comments } { Link }

Renewable energy is energy which can be replenished at the same rate it is used. Renewable energy sources contribute approximately 25% of human energy use worldwide. The prime source of renewable energy is solar radiation, i.e. sunlight. The Earth-Atmosphere system supports approximately 5.4 x 1024 joules per year in the solar radiation cycle (Sorensen, 2004). Mankind's traditional uses of wind, water, and solar power are widespread in developed and developing countries; but the mass production of electricity using renewable energy sources has become popular only recently, reflecting the major threats of climate change due to pollution, concerns about the exhaustion of fossil fuels, and the environmental, social and political risks of fossil fuels and nuclear power. Many countries and organizations promote renewable energies through taxes and subsidies. Varying definitions of the term renewable energy have been adopted to define eligibility under these policies.

Wind Power

{ 7:24 AM, 26/3/2007 } { 0 comments } { Link }

Kinetic energy in airflows can be used to run wind turbines. Some of these turbines are capable of producing up to 5 MW of power. Though turbines with rated output of 1.5-3 MW have become the most common for commercial use. The power output of a turbine is a function of the cube of the wind speed, so higher-power outputs can be achieved as wind speed increases. Though turbines must shut off at extreme wind speeds to prevent damage.

Locations where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms. Wind is the fastest growing of the renewable energy technologies. Over the past decade the global maximum capacity of wind power increased from 2,500 MW in 1992 to just over 40,000 MW at the end of 2003, at an annual growth rate of near 30%, (maximum capacity, in this case, does not count load factor). Due to the intermittency of wind resources, most deployed turbines in the EU produce electricity an average of 25% of their rated maximum power (a load factor of 25%), but under favourable wind, turbines can reach 35% or higher of their capacity. The load factor is generally higher in winter. This would mean that a typical 5 MW turbine in the EU would have an average output of 1.7 MW. Globally, the long-term technical potential of wind energy is believed to be 5 times current production global energy consumption or 40 times current electricity demand. This could require large amounts of land to be utilized for wind turbines, particularly in areas of higher wind resources. Offshore resources experience means wind speeds of 90% or greater than that of land, so offshore resources could contribute substantially more energy then land turbines. This number could also increase with higher altitude ground-based or airborne wind turbines.[5] Wind strengths near the Earth's surface vary and thus cannot guarantee continuous power unless combined with other energy sources or storage systems. Some estimates suggest that 1,000 MW of conventional wind generation capacity can be relied on for just 333 MW of continuous power. While this might change as technology evolves, advocates have suggested incorporating wind power with other power sources, or the use of energy storage techniques, with this in mind. It is best used in the context of a system that has significant reserve capacity such as hydro, or reserve load, such as a desalination plant, to mitigate the economic effects of resource variability.

Solar Power-Electricity

{ 8:40 AM, 19/3/2007 } { 3 comments } { Link }

Solar power for electricity generation has limited potential, due to the fact that various conditions can reduce the power and that it is intermittent. First, solar input is interrupted by night and by cloud cover, which means that solar electric generation inevitably has a low capacity factor, typically less than 15%. Also, there is a low intensity of incoming radiation and converting this to high-grade electricity is still relatively inefficient (12 - 16%), though it has been the subject of much research over several decades.

The power is from a solar panel is harvested through Photovoltaic (PV) cells which are made from semiconductors such as silicon. Simply, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. The energy knocks electrons loose, allowing them to flow freely. PV cells also all have one or more electric fields that act to force electrons freed by light absorption to flow in to a current of electricity. By placing metal contacts on the top and bottom of the PV cell, we can draw that current off to use externally. For example, the current can power a calculator, a light etc. This current, together with the cell's voltage (which is a result of its built-in electric field or fields), defines the power (or wattage) that the solar cell can produce.