Alternative Energy
What is Alternative Energy?
Some of the definitions are:
- Energy that is not popularly used and is usually environmentally sound, such as solar or wind energy (as opposed to fossil fuels). (Natural Resources Defense Council)
- Energy derived from nontraditional sources (e.g., compressed natural gas, solar, hydroelectric, wind). (Natsource)
- Energy derived from sources that do not use up natural resources or harm the environment. (Princeton University)
However, what most of the Alternative energies have in common, is:
- Its not a fossil fuel,
- Its not finite,
- It tends to be less harmful to the environment.
Why do we need alternative energy?
Importing crude oil is costing us dearly. -- Australia is currently spending $12 billion on importing petroleum products.That is 72 per cent of our current account deficit. This figure has increased by 58 % in the two years since 2003-04.
A major contributor to that has been the continuing decline in the production of Australia’s oil—from 31 billion litres in 2001 to just over 16.4 billion litres in 2007.
We are now producing less, importing more and paying more for the imports.
We are using some 20,000 Million litres of petrol per year. (The USA uses about 550,000 Million litres per year).
Australia has the capacity to produce 110 million litres of ethanol per year.
Only 25.1 million litres have been sold in the 6 months to June 2007.
- Using alternative energy is better for the environment
- Using homegrown energy is better for your health
- Using Biofuels is better for the (Rural) economy
- It makes us less dependant on foreign imports
It's not easy being green, but is it affordable?
The cost of producing energy (in both dollars and the cost to the environment) depends on how it is made and where it is used.
The cleanest form of energy is electricity.
However, although electricity is very clean, no green house gases at all, it needs to be produced first.
Production of electricity may or may not be so clean.
Most of the electricity produced in Australia comes from coal fired power stations.
And no matter how efficient or "clean"; they produce Carbon Dioxide.
We also have Gas Fired and Oil fired power stations, and again, they produce Carbon Dioxide.
There are some Biomass power stations, and they produce CO2 but it is from renewable resources, so CO2 produced in the
electricity generating process should be absorbed by the plant material used to power the station.
Hopefully this leads to a zero overall emission.
Examples of Alternative Energy
- Wind Power
- Wave Power
- Biomass - Biofuel
- Hydrogen
- Solar
- Geothermal
- Hydroelectric
- Nuclear (not renewable, but does not produce Carbon Dioxide)
Wind Power
This type of energy harnesses the power of the wind to propel the blades of wind turbines.
These turbines cause the rotation of magnets, which creates electricity.
Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity.
Turbines range in size from 50 to 750 kilowatts.
Turbines start producing electricity at winds of between 12 and 25 km/hr but have to shut down at about 110 km/hr.
Turbines cannot operate at wind speeds above about 110 km/hr because their generators could overheat.
Wave Power
Wave power is the extraction of energy from waves in large bodies of water such as oceans and large lakes.
Biomass
Biomass is organic matter such at grasses, agricultural crops or even trees.
It is used as a solid or can be converted into a liquid Biofuel.
A liquid fuel, ethanol or biodiesel, derived from sugar or starch rich or oil rich plants.
Traditionally only part of the plant is being used, however recently the "leftovers" are being used as supplements for farm animals or through advanced bio ethanol technology, allowing fuel ethanol to be made from cellulosic (plant fibre) biomass.
As a solid it can be used to produce electricity.
(The EarthPower Biomass Plant in NSW has a capacity of 3.9 MegaWatt)
As a liquid it can be used for transport.
Biofuel is environmentally friendly, by taking CO2 out of the air while growing.
At the same time it reduces the dependence on foreign oil and supports the rural economy.
Landfill Gas
Landfill gas (LFG) is created as solid waste decomposes in a landfill.
This gas consists of about 50 percent methane (CH4), the primary component of natural gas, about 50 percent carbon dioxide (CO2), and a small amount of non-methane organic compounds.
Using LFG for energy is a win/win opportunity.
Instead of allowing LFG to escape into the air, it can be captured, converted, and used as an energy source.
Using LFG helps to reduce odors and other hazards associated with LFG emissions, and it helps prevent methane from migrating into the atmosphere and contributing to local smog and global climate change.
Hydrogen
Hydrogen is a gas; H2.
Hydrogen is all around us, in the form of water, H2O, and in the form of HydroCarbons, like Oil and natural gas. It's in plants, in foods, it's everywhere.
However in order to use it as a fuel, you need to extract it.
In the case of water, you need to remove the O, the Oxygen part, in the case of HydroCarbons you need to remove the Carbon part(s).
Hydrogen can be produced by electrolysis of water.
However you need electricity to do this and at the moment electricity is mainly produced in coal fired power stations (producing Carbon Dioxide).
Another way is to strip the hydrogen from carbohydrates, like natural gas.
The problem with that is that the carbon is left behind and that the process itself is energy intensive.
Furthermore, natural gas is already a lot more environmentally friendly than oil and should be used directly as a fuel.
Hydrogen, once burned it produces only water.
So, although Hydrogen is a very clean and green fuel, at the moment, the production of hydrogen is not.
Solar
Solar power involves using solar cells (Photovolteic) to convert sunlight into electricity.
Or
using sunlight hitting solar thermal panels to convert sunlight to heat water or air.
Or
using sunlight hitting a parabolic mirror to heat water (producing steam).
Or using sunlight entering windows for passive solar heating of a building.
Geothermal
Geothermal ("earth heat") energy has tremendous potential for producing electricity.
Geothermal energy harnesses the heat energy present underneath the Earth.
The hot rocks heat water to produce steam.
When holes are drilled in the region, the steam that shoots up is purified and is used to drive turbines, which power electric generators.
There are 3 basic types of Geothermal power plants used today. Flash, Steam and Binary.
Flash Steam
The most common type of geothermal power plant to date is the flash power plant with a water cooling system.
This system uses geothermal reservoirs of water with temperatures greater than 182°C (360°F).
Because the water is under pressure, the water stays in a liquid form, rather than as steam.
In this system, very hot water flows up through wells under its own pressure.
Water is pumped from the reservoir to the power plant.
As the water is pumped up, the presure reduces.
The drop in pressure causes the water to convert or "flash" into steam that is separated in a surface vessel (the steam separator) and delivered to a turbine.
The turbine powers a generator producing electricity. Leftover water and condensed steam are injected back into the reservoir for reuse.
Flash plants emit small amounts of steam and gases.
Dry Steam
Hot (over 150 °C) pressurized steam is piped directly from the geothermal reservoir to run the turbines, producing electricity.
The only significant emissions from these plants is steam (water vapor).
Minute amounts of carbon dioxide, nitric oxide, and sulfur are emitted, but almost 50 times less than at traditional, fossil-fuel power plants.
Energy produced this way currently costs about 4-6 US (5-8 AU) cents per kWh.
This type is the least expensive geothermal powerplant to produce electricity.
Unfortunatly, geothermal sources with dry steam generation capacity are very rare.
Binary Cycle:
Uses lower-temperature, but much more common, hot water (35 °C– 150 ° C).
The hot water is passed through a heat exchanger, which vaporizes (turns into "steam") a secondary fluid.
This secondary (working) fluid such as isobutene boils at a lower temperature than water.
The two liquids are kept completely separate through the use of a heat exchanger.
The heat exchanger is
used to transfer the heat energy from the geothermal water to a secondary fluid
This secondary fluid vaporizes into gaseous vapor (like steam) and the force of the expanding vapor turns the turbines that power the generators.
When the heat energy is converted into kenetic energy (to drive the turbines) the vapour cools down and the fluid condensates (becomes a fluid again).
Because it is a closed circuit system, there are no emissions.
The cost of running this plant is slightly more expensive, at about 7-11 AU cents per KWh.
(This compares to about 3.5 cents AU per KWh for Coal fired power stations)
Currently researchers are working on new technologies to improve the heat exchangers, making the plant more efficient, which will reduce the cost of electricity produced.
The principle of geothermics is being used in other industries, like oil and gas production.
Oil and gas wells are typically thousands of feet deep and often produce very hot fluid.
Along with the oil and gas, these wells produce water that must be separated from the oil and gas and is usually re-injected.
A new technology is currently being demonstrated at the Rocky Mountain Oilfield Testing Center (also known as the Teapot Dome Oilfield) near Casper, Wyoming.
Here the energy derived from the hot fluid during oil and gas production is used to produce electricity that can power the oil and gas pumps.
This could
eliminate the need to purchase additional electricity (or construct power lines) to run the oil and gas facility.
Hydroelectric
There are three types of hydropower facilities: impoundment, diversion, and pumped storage.
Some hydropower plants use dams others do not.
Impoundment:
The most common type of hydroelectric power plant is an impoundment facility. An impoundment facility uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity.
The water may be released either to meet changing electricity needs or to maintain a constant reservoir level.
(Example: The Warragamba Power Station in NSW has a capacity of 50 MegaWatts.)
Diversion:
A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock.
It may not require the use of a dam.
Pumped Storage:
When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity.
Nuclear
Nuclear power stations work similar to fossil fuel power plants, (a very big steam engine) except for the fact that the heat is produced by the reaction of uranium inside a nuclear reactor.
The reactor uses Uranium Oxide (UO2), usually pellets, formed into rods.
The rods are arranged into fuel assemblies in the reactor core.
The Uranium atoms are split in the process of fission, releasing a large amount of energy in the form of heat.
The process continues, as a chain reaction with other nuclei takes place.
The heat released in this process, heats water to create steam, which spins a turbine, producing electricity.
All of these methods of generating energy have their advantages and disadvantages.