Renewable and they are always available. As reported

 Renewable energy,
or alternative energy, is simplely a kind of energy or a source of energy that
can recover after human’s consumption, like its name “renewable”. According to Harper
Collins said in Collins English Dictionary
(2014), renewable energy is energy from various sources which are derived
from nature, such as sun, water, wind, or other natural processes, and they are
always available. As reported by Andrea Aust (citied in “Nonrenewable and
renewable energy sources”, 2014), since the beginning of human society, mankind
has utilized renewable resources to stay alive; for instance, they used wood
for cooking and heating, wind and water for milling grain, and sun for creating
fires. To be more precise, renewable energy is definitely in contrast with
energy that comes from fossil, or nuclear fuel, or we can call “nonrenewable”.
They includes coal, oil, natural gas, and are available in limited supplies;
meanwhile, alternative energy is replenished naturally and in a very short
period of time, so that it will never run out.

In the
world today, there are five major types of renewable energy resources. Firstly,
solar energy, energy generated by sun’s heat of light, is one of the most well
known power. Secondly, wind energy created by converting wind currents into a
form of energy is one of the most widespread used. Thirdly, hydropower
(hydroelectricity, or water power) is the oldest power in the world. Finally,
the last two resources are geothermal power, energy stored as heat in the
earth, and bioenergy, which is derived from biomass to generate electricity and
heat. In the article “What is renewable energy?” (n.d.), Australian Renewable
Energy Agency, also known as ARENA, has claimed that just as there are many
natural sources of energy, there are many renewable energy technologies and

2.2. What are the benefits
when using renewable energy sources?

 In our modern life nowadays, governments of many
countries have made more and more effort to promote five main alternative
sources of energy above to improve people’s life. Indeed, taking advantage of
renewable energy actually can affects positively to human’s daily life. Mark Z.
Jacobson (n.d.) used to said every
dollar spent on nuclear is one less dollar spent on clean renewable energy and
one more dollar spent on making the world a comparatively dirtier and a more dangerous
place, because nuclear power and nuclear weapons go hand in hand. There is an urgent need to stop
subsidizing the fossil fuel industry, dramatically reduce wasted energy, and
significantly shift our power supplies from oil, coal, and natural gas to wind,
solar, geothermal, and other renewable energy sources (Bill McKibben, n.d.). The
trend of using renewable energy has gradually become the worldwide trend not
only because of the inexhaustibility of this kind of energy resource but also
for great benefits it has brought to people.

 The first benefit, also the clearest benefit,
that renewable energy use give us is the decrease in global warming. Global
warming, also referred to climate change, is considered as the most complex
concern of many countries around the world. This problem is contributed mainly
by greenhouse
gas emission, which is created by human’s activities. Those activities such as
burning fossil fuel to provide energy for manufactories, or vehicles like cars
are overburdening our fresh air with carbon dioxide (CO2), methane (CH4), and
other greenhouse gases. Renewable energy sources, however, show a little or
even no connection with the global warming emissions. Wind and other clean, renewable energy will help end our
reliance on fossil fuels and combat the severe threat that climate change poses
to humans and wildlife alike (Frances Beinecke, n.d.). That is absolutely true.
Wind power and solar power get electricity from the sun and the wind, which
theoretically are inexhaustible sources of energy and show no contributions to
the climate change. Hydroelectricity also works effectively by using endless
source, water. Other clean resources produce zero emissions as well. Therefore,
the more people use renewable energy, the more environment pollution problems
are solved.

The second benefit of
using alternative resources is the greatly improved public health. Lots of
diseases, including cancers, heart attacks, are likely to associated to air and
water pollution caused by greenhouse gases and chemicals from industry, so if
renewable sources of energy can reduce the emissions of greenhouse gases, they
can bring major health benefits to people. The Clean Energy and Climate Change
Office of the U.S. Environmental Protection Agency has made a study on people’s
health. According to the study, Americans spend an estimated $361.7 to $886.5
billion each year on their health conditions related to the use of fossil fuel.
In a new study published in 2015 in Nature Climate Change, renewable electricity projects and energy
efficiency measures could have health benefits worth millions of dollars a year.
Moreover, most of clean energy technologies do not produce anything that
negatively affect to air and water environment. Solar, wind systems generate
power without links with air pollution and water contamination. In addition, as
reported in ” Six Benefits of Renewable Energy We Need to Consider” (2016) in The
Alternative Daily, biomass
helps eliminate fossil fuel emissions while cutting down on the waste going to
landfills. To sum up, making use of renewable sources of energy not only solve
environment pollution problems but also help people avoid many diseases caused
by the pollution.

2.3. What are drawbacks when using renewable
energy sources?

 Althought clean sources of energy have really
great benefits, we cannot deny that they also get some clear drawbacks to our
life. There is a rapidly growing demand for renewable energy in the whole
world. However, we rushed into renewable energy without any thought, and the
schemes are largely hopelessly inefficient and unpleasant (James Lovelock,

One of the biggest drawbacks of
alternative resources use is the high development cost. This is also the huge
obstacle for the development of renewable energy in the future (The Editorial
Broad, cited in “A Renewable Energy Boom”, 2016). According to the article, Despite increased private investment in renewables, the
United States and other industrialized countries have not
lived up  to their pledge at
the Copenhagen conference in 2009 to provide $100 billion a year to underwrite climate projects in
poorer countries. Building a renewable system actually needs a giant number of
money to complete, so that this is a very hard issue for developing countries,
and spending a vast amount of investment in them is little risk for developed
countries like China, and U.S. For example, solar energy need a lot of money
for manufacture and implementation of solar panels, or wind power needs wind
farms and wind turbines, or geothermal energy wants people to set up a costly
workplace in areas of volcanic activities, and dams for hydroelectricity are
extremely expensive. As the International Renewable Energy Agency (IRENA)
reported (cited in Renewable Power Generation Cost in 2017, 2017), all renewable energy technologies should be
competitive on price with fossil fuels by 2020. However, the current cost of
renewable technology is far bigger than that of traditional fossil fuel.

 Another clear disadvantage of alternative
energy sources is the shortage and unreliability of energy supplies. In the
article “Renewable Energy Pros and Cons” (n.d.), unlike coal powered electric
plants that produce abundant supply of power, renewable sources can not produce
that much of energy in a short span of time. This means that we should use less
energy, or establish more energy plants. The lack of capacity to make energy to
meet people’s demands results from the problem on the supply. Unpredictable
weather conditions can cause disruptions in service when using renewable energy
sources, as alternative energy often relies heavily on the weather for its
source of power. According to Ashraf Mahmoud’s article ” The Advantages and
Disadvantages of Renewable Energy” (2016), hydro generators need rain
to fill dams to supply flowing water; wind turbines need wind to turn the
blades, and solar collectors need clear skies and sunshine to collect heat and
make electricity. This totally dependence on weather has made the development
of renewable energy technology still challenging nowadays.