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)

Neither of the definitions exactly describe the alternative energies noted below. 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 last year. 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.

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. But: although electricity is very clean, no green house gasses at all, it needs to be produced first. And it is the production which 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 its 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 nil 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. But in order to use it as a fuel, you need to purify 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, the production of it is not.

Solar
Solar power involves using solar cells 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 2 basic types of Geothermal power plants used today. Steam and Binary.

Steam: Geothermal Electricity - Steam
This technology is already being used in the USA. Hot (over 150 °C) pressurized steam from the earth turn generators, which in turn drive turbines to produce electricity. The only significant emission 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.

Binary: 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 then runs the turbines. 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.

Hydroelectric

There are three types of hydropower facilities: impoundment, diversion, and pumped storage. Some hydropower plants use dams and some do not.

Impoundment:
An impoundment hydropower plant dams water in a reservoir. 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 pelets, 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.