Hello and welcome to the TranslatorsCafe.com channel. In this video we will talk about
energy. We will discuss units for measuring energy, different properties of energy, and
ways of its generation, including green energy. Finally we will discuss some other interesting
facts about energy. Energy is a notion central to physics, chemistry,
physiology, and life itself. Neither life nor motion is possible without energy. In
physics it is defined as the property of objects or fields, which allows it to perform work
on other objects, for example to cause motion. The SI unit for energy is a joule. One joule
represents the amount of energy expended while applying a force of 1 newton to a body and
moving it for one meter.
The kinetic energy of a moving object is the
energy which this object possesses as a result of its motion. A moving body maintains its
kinetic energy until its speed changes. Kinetic energy of an object that is not moving is zero.
Potential energy, on the other hand, is the
energy of a body at rest. It is the energy needed to keep the body in the current position
in space. For example, before a football is hit by the
player, the forces acting upon it (like gravity and the resistance of the Earth), make it
stay still in that position. At that moment its potential and kinetic energy is zero.
Once it bounces off after the kick and is moving away, it has both kinetic and potential
energy. As it moves, kinetic energy converts to the potential energy or vice versa.
Let us look at an example of such energy conversion. When a stone is thrown directly up, it flies
and slows down. As it slows down its kinetic energy is converted to potential energy. Eventually
the potential energy peaks when the stone stops flying up.
The stone then falls down, and as it accelerates, kinetic energy increases, while the potential
energy decreases. Eventually at the moment of impact with the Earth, right before the
stone stops moving its kinetic energy reaches maximum.
The law of energy conservation states that the total amount of energy in an isolated
system stays constant. Throughout the fall of the stone in the example above its potential
and kinetic energy is changing, but the sum of the two is constant, because kinetic energy
converts to potential energy, and vice versa.
Potential and kinetic energy can be used to
perform work, such as putting objects in motion. Humans have used this principle to accomplish
numerous difficult tasks with the help of various devices and machines.
For example, kinetic energy of moving water was used for many centuries to move water
mills that produce flour. As more and more people use technology in everyday life, for
example cars and computers, the demand for energy is constantly increasing.
Currently, the primary sources of energy are non-renewable. This means that they are fuels
mined from the Earth, and their source is not being replaced at a speed fast enough
to meet the oncoming demand. Examples of such fuels are coal, oil, and uranium. The latter
is used to produce nuclear energy. In recent years renewable energy, or energy
from sources that can be renewed by human technology, is on the agenda of most governments
and many international organizations such as the UN.
A large number of research projects is focused on finding renewable energy that can be generated
with the minimal cost. Some of the currently used renewable energy technologies generate
wind, solar, and wave energy.
Energy generated for industrial and home use
is generally converted into electric energy. Electric power is generated by batteries or
electric generators. The first power plants generated electricity from coal and hydroelectric
power, but eventually other sources appeared, such as petroleum, natural gas, solar, and
wind energy sources. The main principle behind power generation
is to convert energy to the kind that is easy to transport and to use — mostly electricity.
Occasionally large industrial facilities generate their own energy, but more commonly energy
production is done in power stations on the industrial scale. Power stations are more
convenient and it is not logistically or economically feasible to produce energy in every household.
This is especially true for generation of power that heavily relies on expensive technology,
or technology that requires constant monitoring and safety measures. Some examples of such
technologies include those used in nuclear, wave, or wind power generation. One of the
reasons that electric energy was chosen as the primary energy source for households and
the industry is that it is easy to transport over long distances using power lines, and
the losses are minimal.
Electricity can be generated from mechanical,
thermal, and other forms of energy. Examples of mechanical energy include energy generated
by turbines that are moved by water, steam, hot gas, or air.
Steam is created by burning fossil fuels or from nuclear reactions.
As we discussed earlier, fossil fuels are non-renewable fuels excavated from the earth
and include petroleum, natural gas, or coal. Renewable sources of energy include biomass
as well as solar, ocean, and geothermal energy. In some areas the power supply infrastructure
is lacking due to economic and logistic constraints. If the power supply is not constant or it
is not possible to access the grid, then backup or portable systems are used.
Many individuals, businesses, and organizations, for example hospitals, use small generators
to produce electricity. These are usually reciprocating engines, which burn fossil fuels
and convert the energy generated in this process into mechanical motion.
Fossil fuels have formed over millions of years from the remains of plants and animals,
under conditions of extreme pressure and heat within the Earth’s crust. They are usually
high in carbon. These fuels release energy when burned, but they also release carbon
dioxide (CO₂), one of the greenhouse gases. At the moment, fossil fuels are the major
source of energy for power generation across the globe. When burned these fuels release
greenhouse gas emissions. The emissions, in turn, contribute to global warming. An additional
problem with fossil fuels is that they are not renewable and are being depleted faster
than the new fossil fuels are being created. If we rely on fossil fuels, one day we will
run out of energy sources.
Nuclear energy is one alternative to fossil
fuels. It is generated through a controlled nuclear fission reaction, where a nucleus
of an atom splits into smaller parts and releases energy. The energy heats water and produces
steam. This steam moves the turbines. Nuclear energy poses safety concerns. Some
of the most notable and infamous nuclear power plant accidents include the Chernobyl disaster
in Ukraine, the Three Mile Island accident in the USA, and the Fukushima disaster in
Japan. After the Fukushima disaster several countries
started the process of re-evaluating their use of nuclear power. Some countries such
as Germany are now working on closing down their nuclear power plants in the near future.
An additional problem is the storage of spent nuclear fuel. Fuel is needed for the fission
reaction to occur, and it can be reused, but eventually it has to be replaced. Some of
the by-products of nuclear power production can be reused in other industries such as
medicine or weapon production, but most of the material has to be stored as radioactive
waste. Currently each country has their own storage
systems for the spent fuel. They include repositories in geological structures or the ocean floor,
as well as storage in pools or casks for spent fuel.
This poses problems and risks such as high
costs, leakage, running out of storage, and hostile attacks on the storage facilities.
Other alternatives include using renewable power sources, such as energy from waves,
sunlight, and wind. At the moment these alternative sources are not developed enough to replace
fossil fuels. However, they are becoming more and more popular thanks to the subsidies provided
by some governments, and also because these energy sources are much less harmful to the
environment than the non-renewable ones.
Solar energy experiments started in the 19th
century, but this technology was not widely used until recently. In recent years, solar
industry is developing very rapidly due to demand and subsidies from governments and
international organizations. Solar farms, which are large areas covered
with solar panels, were first built in the 1980s. Most often solar energy is collected
and electricity is generated by means of photovoltaic panels. Sometimes heat engines are used in
which solar energy heats water and resulting water vapour rotates the turbines, which in
turn rotate generators.
Wind energy has been used by humans for a
long time. The first major use was in sailing, as far as 7000 years ago. Windmills have also
been in use for hundreds of years. The first wind turbines were created in the 1970s.
Tidal energy has also been used since the time of the Roman Empire, but the energy of
waves and currents has only been used recently. In recent years stations that harvest wave,
tidal, and current energy are being built and tested. While the idea of generating energy
from marine power is not new, devices that harvest this energy on a large scale need
to be further developed and tested. This is mainly due to high costs of building such
power stations, and to the lack of advancement in current technologies.
Biomass or biofuel generates energy when plant material is burned. During this process solar
energy that plants generated through photosynthesis is released as heat. It is widely used in
everyday life, for example to provide warmth for heating and cooking, and also as fuel
for transportation. Alcohols and oils can be made from plants.
Animal fat-based biofuel is also in use. One variation of biofuel, biodiesel, is used in
the automotive industry both as an additive to other diesel fuels, or by itself.
The Earth stores energy in its core in the form of heat. Earth’s crust has been hot
since its original formation, and additional heat is constantly generated from radioactive
decay of minerals. Until recently, this energy has been accessible
mostly in the areas that lie around the borders of tectonic plates, where hot springs are
present. Now, geothermal wells are created to have
access to this energy more widely. This is a costly process, however.
Hydroelectric energy is another alternative to fossil fuels. Hydro generated power is
considered by many to be clean energy with little negative environmental impact. Indeed,
greenhouse gas emissions are not a problem for hydroelectric energy as they are for fossil
fuels. Hydroelectric energy is generated by water
flow. This type of energy has been in use by humans for a long time. A watermill is
one example of using it. Electricity is currently generated at hydroelectric
stations by harvesting kinetic energy of flowing water of rivers, or potential energy of water
in dams. This energy moves water turbines. The dams use the height difference between
the reservoir from which the water flows, and the river into which the water flows.
Despite the positive aspects of hydroelectric energy, numerous problems exist with its generation.
For example, displacing and damaging habitats when building dams causes considerable harm
to the biodiversity. As a result of building dams plants and animals become cut off from
the resources normally available in their ecosystem. For example, fish may not be able
to go upstream to lay eggs. Some species may be unable to adjust to the new environment.
Energy in nutrition and exercise is usually measured in kilojoules or food calories. One
food calorie is formally defined as the amount of energy needed to raise the temperature
of one kilogram of water by one degree in the Kelvin scale. One food calorie is equivalent
to one kilocalorie or 1000 calories in the scientific notation. This is about 4.2 kilojoules.
When we talk about food calories the word “food” is often omitted, so they are called
simply “calories”. There are 9 calories per gram in fats, 4 calories
per gram in carbohydrates and proteins, and 7 calories per gram in alcohols. Some other
substances also contain calories. This energy stored in foods is released and made available
to the living organism during metabolism.
The word “energy” is widely used in marketing
products. For example, energy drinks are sold as performance-enhancing beverages. They generally
contain stimulants like caffeine, sometimes herb extracts, and plenty of sugar.
Stimulants increase blood flow, heart rate, blood pressure, and temperature, and produce
a feeling of “high,” of being energized and capable. This happens because the increase
in blood flow brings more oxygen to the brain. Energy drinks should not be consumed while
exercising, because they negatively affect the electrolyte balance in the body.
They often contain very high levels of stimulants and provide a brief boost period followed
by a withdrawal period, which resembles caffeine, alcohol and sugar withdrawal.
Energy drinks may also have other side-effects such as nausea and vomiting, headaches, high
blood pressure, irregular heart rate, and insomnia.
It is better not to drink energy drinks at all. Your natural energy is enough for you.
If you feel tired, just have a good rest. Thank you for watching! If you liked this
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