To cushion global warming effects, cutting emissions is essential; this has made individuals, government and institutions look towards renewable and sustainable energy sources. These are naturally replenished sources that are harnessed to produce energy; examples are the sun and wind. Another source that is replenished naturally and has not been used as a source of energy is the Earth Magnetic Field or Geomagnetic Field. Planet Earth has its own magnetism originating from its inner core. It is weakly felt on the surface and it extends into outer space to protect planet earth from streams of charged particles from the sun. Earth Magnet like other magnets has both North Pole and South Pole; these are points where its magnetic force is stronger. Use of this source of energy is designed for places close to the poles on Earth. Energy is released when existing fields between two magnets is destroyed, so if magnet on a surface is attracted by the Earth Magnet, when the field is destroyed, energy is released, the energy released can be used to drive working parts certain object or power devices. Using this method, Earth Magnetic Field has the prospect to be used as a source of sustainable energy to power some engine, making the maximum output less dependent on air and fuel intake reducing emissions in someway. This paper presents an overview of the Geomagnetic Field and presents a critical review of possible ways it can be used as a source of sustainable energy.
Planet Earth like some others on our Solar system has an active magnetic field. The Earth Magnetic Field (EMF) has a number of applications to man and his environment. For example, it used in Navigation. EMF extends several kilometers into space to form Magnetosphere, a space that acts as a shield from solar wind which is a stream of high intensity charged particles emanating from the sun. 
EMF comes from an ocean of iron, which is an electrically conducting fluid in constant motion; it is as hot as the surface of the sun, over 60% in width as the moon, spinning at its own rate more than the Earth above it. 
Convection caused by heat radiating from the core, along with the rotation of the Earth, causes the liquid iron to move in a rotational pattern, it is believed that these rotational forces in the liquid iron layer leads to weak magnetic forces around the axis of spin, making EMF weak on the surface with it strength measured at about 30-60microteslas while a bar magnet has a field strength of 10millitesla. However, if we consider the total volume of the EMF, its total energy is extremely large. 
A ship under construction or repair will acquire permanent magnetism due to hammering and vibration while sitting stationary in the EMF. The EMF may not be so strong compared to local magnetic fields, but it also affect mineral all over the surface of the Earth. 
How strongly a bar will retain its magnetism on removal from a magnetizing field like the EMF depends on the strength of the field, the degree of hardness of the iron and the physical stress applied to the bar like vibrations and hammering while in the EMF. However, the soft iron be used to attract the EMF will have its own magnetism; just that on attraction to the EMF will acquire induced magnetism. 
EMF is weak compared to normal magnets but it can induce a metal, or attract an already made magnet, when the metal is no longer induced or attracted, it releases energy, the energy can be channeled to the combustion chamber of engine for use, it can be used to lit substances and perform some other task aimed at saving power and reducing emissions.
2.0 THEORETICAL BACKGROUND
Energy is needed to create a magnetic field, this energy can be reclaimed when the field is destroyed, simply means that energy is stored in the magnetic field. Since energy is neither created nor destroyed, but can be transformed from one form to another, the energy harnessed from a destroyed magnetic field can be converted to mechanical energy for use in the combustion chamber.
The Earth Magnetic Filed (EMF) as other magnets has a North Pole and a South Pole, these Poles called Geographic North and South Poles are found on different places on the Earth surface. The Geomagnetic South Pole and North Pole are relatively at the same direction with Geographic North and South Pole. By verification, reverse is the case; to avoid conflicting names, they are used similarly. 
Initial development of this research basically concerns region close to Geomagnetic North Pole in Resolute Bay Canada and Geomagnetic South Pole in Southern Australia.
Engines that power devices such as automobiles, generators, machines and other devices will harness the EMF using energy saved overtime. Some of these engines have ‘exposed’ combustion chamber. This means that their combustion chamber is not sealed in solid iron case.
A ship usually acquires induced magnetism when placed in the EMF. Factors responsible for the ship or iron to acquire induced magnetism include the EMF intensity, iron physical properties and dimensions, and the alignment of the iron to the magnetic field; these factors determine how strongly it will be magnetized by the EMF. 
A magnet on the surface of an object close to the poles will be attracted to the EMF because a magnet produces a field and responds to other fields. Depending on its alignment, the magnet maybe tilted a little towards the magnetic field. When this happens, energy is trapped in the field created. For engine whose combustion chamber is somehow exposed, the energy can be used for moving parts to help power the vehicle not limiting the power to burnt fuel.
If we consider Pole or close to polar region, and align a soft iron towards the Earth Magnetic field (EMF), it is attracted, when it does, some energy is saved around the surface of the soft iron. This saved energy can be harnessed and used.
A soft iron inclined towards the EMF can be attracted or repulsed depending on which of its poles is aligned towards the EMF; its attraction or repulsion effects can be used to push against other substances to give some additional energy to its working part.
If a magnetic material is exposed to the EMF, if in motion, it sometime align towards the EMF, making it acquire magnetism overtime, the material’s field strength will also increase as time goes on. This material can therefore attract other paramagnetic or ferromagnetic materials close to it.
For example, if the crankshaft of an engine is partly exposed to the EMF, since it is constantly in motion, overtime it acquires some permanent magnetism from the EMF, this permanent magnetism can be used to additionally attract the piston head to it.
On attraction of the piston head, it delivers an output that is not directly a product of the working fluid of the engine, making the engine deliver a higher output not exactly proportional to the air-fuel intake combination in the combustion chamber.
Research can develop a soft iron magnet such that when attracted to the EMF, it changes position after some time, when it does this, energy is released, this energy can be saved or converted to make it useful to power substances.
Every time an existing magnetic field created between the EMF and a bar magnet is destroyed, energy is released, no matter how small it is, the energy can be saved or used and it is not expected to be used up since it is obtained from a sustainable energy source.
Much more research into the Earth Magnetic Field (EMF) and its processes should be carried out. As stated earlier, the true North Pole of the Earth is around the direction of the Geographic South Pole, and the true South Pole of the Earth is around the direction of the Geographic North Pole.
To avoid conflicting Geographic and Geomagnetic Pole locations, they are termed as being towards the same direction. Geomagnetic Pole is usually reversed. If it is to occur anytime soon, then Geographic North Pole will be in the same direction with true North.
Magnetic reversals have occurred many times in geologic past and the last one occurred thousands of years back, there is no regularity or pattern as it has been random in the past 200million years. 
Some scientists predict that Planet Earth maybe close to another reversal, since there has been a general decrease in EMF strength at about 10% in some places. When reversal is to occurs, the EMF shuts down for sometime; if it does, at this time, the Earth Magnetosphere will become inactive and Planet Earth will be bombarded by cosmic rays at higher intensity than today. These cosmic rays may have the ability to cause tissue damage, similar to x-ray effect.
If the EMF can be harnessed and used as a source of sustainable energy, further understanding of the field can be obtained. This will contribute to research on reversals and future application of the Earth Magnetic Field.
APPENDIX – A
RENEWABLE AND SUSTAINABLE ENERGY
Renewable energy is defined energy obtained from sources that can be replenished naturally with the passage of time. Examples are solar and wind energy. The Sun and Wind have existed long before man and will still be in existence for many more of years to come.
Sustainable energy can be described as energy available to meet present needs and future needs effectively. Sustainable energy is closely related to renewable energy and is sometimes used together as Renewable and Sustainable energy.
Scientists developed materials to harness energy from these sources for man’s benefit. There are many other examples of natural existing sources, research to channel them for use keep growing in order reduce emissions and cut costs. 
In the 21st Century, impulse to go green has increased especially for the purpose of cutting emissions. Saving costs is another advantage of using renewable energy sources such that cost equality of renewable energy use and convectional energy use has been achieved in some region. Researchers understand that most naturally existing sources can be channeled to produce energy; just that findings to develop materials to harness them needs to grow extensively also.
Moving towards energy sustainability, effort is being made to improve energy efficiency and reduce carbon intensity of the world economy. Renewable energy has reached a clear tipping point in the concept of global energy supply. Renewables comprised fully one-quarter of global power capacity from all sources and delivered 18% of global electricity supply in 2009. 
In a number of countries, renewables represent a rapidly growing share of total energy supply which includes heat and transport. About 70million households worldwide employ solar hot water heating. There is also growth and investment in power generation; transport fuels; and heating and cooling. 
Magnetism can be termed as an effect produced when a material responds at an atomic or subatomic level to magnetic field. A magnetic field is a region within which magnetic force is felt, it the line of force surrounding a permanent magnet or a moving charged particle. 
Usually, magnetism and magnetic fields are terms connected with magnets; magnets are materials that produce a magnetic field either temporary or permanently as temporal or permanent magnets respectively. Magnetic field is invincible, and its lines of forces are imaginary meaning that they don’t exist physically. Magnetic field is responsible for the notable property of a magnet which is a force that pulls on other ferromagnetic materials like iron and attracts or repels other magnets. 
Ferromagnetic materials are materials like iron, nickel or cobalt which become magnetized in a magnetic field and retain their magnetism when the field is removed. The soft materials are magnetized when a magnetic field is applied, but do not retain their magnetism when the field is removed. Hard ferromagnetic materials retain magnetism when the field is removed. Common magnets around are usually made of hard ferromagnetic materials. 
Paramagnetic materials of examples as Aluminum and platinum become magnetized in a magnetic field but their magnetism disappears when the field is removed. They are weakly attracted to a magnet; their effects can be detected by using sensitive instruments or extremely strong magnets. 
Application of magnets and magnetic field on Planet Earth cuts through several aspect of life; many migrating animals such as birds, whales and butterflies use magnetism for navigation. Magnets are also used in several technologies useful to man and his; protection of Planet Earth from high intensity cosmic rays is made possible by Extension of the Earth Magnetic Field to outer space called the Magnetosphere.
Magnetism in a magnetic material can originate from moving electric charges or electrons’ orbital angular motion around the nucleus or the electron intrinsic magnetic moment. Magnetic moment is the torque exerted on a magnet or dipole when it is placed in a magnetic field. 
Telsa (T) A unit of magnetic flux density in the International Systems (SI)
Of Unit, equal to the magnitude of the magnetic vector
milliTelsa (mT) A unit of Magnetic Flux density in SI unit equal to
10[sup]-3[/sup] (1/1000) T
microTelsa (μT) A unit of Magnetic Flux density in SI unit equal to
10[sup]-6[/sup] (1/1000000) T
Am grateful to organizations, institutions and individuals who have written papers, articles and presentations in related topics on Magnetism, Geomagnetism, Renewable and Sustainable Energy which are keywords of this paper; efforts and results of scientists across the globe towards making the world a better place will remain the determining factor for present and future options of change.
Thank You All.
1. Abdul-Razzaq. W., R.D Biller, (2010) Geomagnetism and Induced Voltage Physics Education 45 368
2. McDonald. R (2005), Planetary Magnetic Fields, Richard Astrological Papers.
3. National Geospatial-Intelligence Agency (2004), Handbook Of Magnetic Compass Adjustment, Formerly Pub. No 226. Pages 4-6
4. NASA Staff (2003), Earth Inconstant Magnetic Field, posted on Science @ NASA Headline News
5. Howard Geller, (2003) Energy Revolution: Policies for a Sustainable Future, Island Press, Washington.
6. Renewable Energy Policy Network for the 21st Century, REN21, (2010)
Renewables 2010 global status report, page 9.
7. National Geospatial-Intelligence Agency (2004), Handbook Of Magnetic Compass Adjustment, Formerly Pub. No 226. Pages 4-5
8. Tatum. J. B., (2003), Chapter 12 Properties of Magnetic Materials, Electricity and Magnetic Updates of Department of Physics and Astronomy, University of Victoria. Pages 4-5