Renewable fuels (i.e., coal, petroleum and natural

Renewable Energies

The electricity requirements of the world including are increasing at an
alarming rate and the power demand has been running ahead of supply. It is also
now widely recognized that the fossil fuels (i.e., coal, petroleum and natural
gas) and other conventional resources, presently being used for generation of
electrical energy, may not be either sufficient or suitable to keep pace with
ever increasing demand of the electrical energy of the world. Also generation
of electrical power by cold based steam power plant or nuclear power plants
causes pollution, which is likely to be more acute in future due to large
generating capacity on one side and greater awareness of the people in this

                 The recent severe energy crisis has forced the world to develop new and
alternative methods of power generation, which could not be fully adopted so
far due to various reasons. Piezoelectric energy generation is one of the
examples of a new unique method of power generation (Royal). The other
non-conventional methods of power generation may be such as solar cells, fuel
cells, thermo-electric generator, thermionic converter, solar power generation,
wind power generation, geo-thermal energy generation, tidal power generation
etc. Some of the less commonly known technologies that will be discussed is
marine energy, hydroelectric, piezoelectric, and phase changing materials.

Marine renewable energy has
the potential to solve both the energy-security and coastal-protection problems
affecting coastal societies. These technologies are capable of producing energy
and significantly reduces the size/impact of tidal waves causing erosion. Marine
energy can be split into two types, mechanical and thermal. Oceans cover more than 70% of Earth’s surface, making
them the world’s largest solar collectors. The sun’s heat warms the surface
water a lot more than the deep ocean water, and this temperature difference
creates thermal energy. Just a small portion of the heat trapped in the ocean
could power the world (Ocean Energy). The type of system we are going to be on
focusing on is called a closed-cycle system. Closed-cycle systems use the
ocean’s warm surface water to vaporize a working fluid, which has a
low-boiling point, such as ammonia. The vapor expands and turns a turbine. The
turbine then activates a generator to produce electricity. 

Mechanical ocean energy is typically some type of
barrage/dam used to convert tidal energy into electricity by forcing water
through turbines to activate a generator. Float systems drive hydraulic pumps
which either directly activates a generator or transfers to a working fluid,
water, or air, which then drives a turbine/generator. This technology has one
of the highest energy generations amongst other renewable energies, yet it has
not been commercialized. There are many cost issues of working in the ocean,
and then you’ve got the problem that no one seems to have settled on a design
that is robust ,reliable, and efficient. In wave energy, you’ve not only got
the height of the wave, but you’ve got the period of the wave, making the
problem much more complicated (Leviton). The cost of this technology ranks
amongst the highest which is a huge setback. If this ever becomes marketable,
it will likely start in places where to cost the transport imported fuels is
high, such as Alaska.

Hydro Power is
one of the largest sources of energy accounting for roughly 20% of the
worldwide demand of electricity and for well resourced countries it accounts
for majority of the energy. For Paraguay 100% of the electricity comes from
hydro power and  lot of it is exported as well. Compared to other sources
of Energy, Hydroelectric Power is one of the cheapest, non carbon Emitting, on Polluting, Mature Energy Sources.
Hydro Power plants have been developed to almost full potential in developed
countries because of their superior characteristics and many more are being
constructed by developing countries like China and India. However, Hydro Power
suffer from disadvantages as well. The failure of a Hydro Dam can result in
massive losses of human life and cause widespread devastation. Large Dams have
always been controversial leading to displacement of people and ecology. They
have also been cited as the reason for earthquakes due to large land changes.
Some advantages of hydroelectric energy include no fuel cost, low operating
costs, little maintenance, low electricity cost, no greenhouse gas emissions, and
reliability. While these advantages are definitely important for a renewable
energy, the disadvantages are fairly serious. Some of the disadvantages are
wildlife/fish get affected, earthquake vulnerability, siltation, dam failure
risk, long gestation time, and the fact that they cannot be built anywhere.

Piezoelectric effect is a unique property that allows
materials to convert mechanical energy to electrical energy and conversely,
electrical energy to mechanical energy. The stimuli for piezoelectric materials
can be human walking, wind, rain, tide and wave etc. This effect can be an
inherent property of the material or it can be imparted to an existing
non-piezoelectric material. However, not every material can be made
piezoelectric, only certain ceramics and polymers have the ability to become
piezoelectric. Recent
developments have been made to create a flexible piezoelectric fiber which can
be integrated or embedded into flexible structures. Piezoelectric effect exists in two domains; namely,
direct piezoelectric effect and converse piezoelectric effect. Direct
piezoelectric effect describes the ability to convert mechanical energy to
electrical energy which is also known as generator or transducer effect while
the converse piezoelectric effect describes the ability of transforming
electrical energy to mechanical energy which is also known as motor/actuator
effect. The electrical energy generated by direct piezoelectric effect can be
stored to power electronic devices and it is known as “energy/power harvesting”
(Vatansever). While all these facts about piezoelectrics are great; there is
one main issue keeping the technology from being heavily marketed.  Energy harvesting applications for
piezoelectric devices is less than 10%. However, this can change dramatically
if the importance of piezoelectric materials is recognized for alternative
energy from nature with zero carbon foot print.

The term “global warming” has been highlighted more and
more every day since it is considered as one of the biggest dangers to life on
earth. It is a fact that one of the factors which cause global warming is high
carbon emission. Growing population and the increasing technology consumerism
contribute to the enhanced usage of energy from coal, oil, electricity etc.
However, sooner or later the mankind is anticipated to run out of the coal and
oil reserves since they are finite and are not renewable. Energy harvesting properties
of these renewable technologies have been known for a long period of
time, however recently more attention has been paid to produce usable materials
for energy generation in the form of electricity to decrease carbon foot print.


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