Energy is a vital need for human beings as it is interconnected with several activities in their life. Choosing a safe, affordable and sustainable source of energy is then the subsequent issue in dealing with energy matters. Especially developing countries are in a more questionable situation as to which types of energy to choose due to the obvious challenges they face technologically and economically.
The traditional sources of energy like fire wood and cow dung are becoming obsolete and threats to human health as well as the environment. The rather modern sources like hydroelectric, fossil fuel and solar energy avail a better means of energy while having their own shortcomings.
Yet nuclear energy is at the disposal of the need to fulfill the growing demand of energy both for the developed and developing countries. Enough potential energy is locked in the earth’s oceans to last millions of years. Their waters contain deuterium, a heavy isotope of hydrogen and the main fuel for a nuclear fusion reactor. Once extracted, the deuterium from just one litre of water could generate as much energy as the combustion of 300 litres of gasoline.
While it will take decades for the potential to become reality, important strides already have been made. Technological and scientific advances today are bringing the technology of nuclear fusion closer to demonstration. To a large extent, the progress in fusion research and development is driven by the world’s growing energy needs, environmental concerns, and population trends.
Burning fossil fuels for energy and electricity production has its limits. Four factors in particular limit utilization: the human health effects of fossil fuel combustion (emphysema, cancer), the environmental effects (acid rain, greenhouse effect, etc.), the need to save hydrocarbons for convenient fuels and chemical feedstocks, the finite reserves of fossil fuels (coal, oil, natural gas).
According to International Atomic Energy Agency (IAEA), fusion, a form of nuclear energy generated when light-weight atoms fuse, is the process at work in every star´s core, releasing an enormous amount of energy. Researchers have been trying to harness fusion and reproduce it on earth in a controlled manner. If they succeed, they will provide the world a safe, sustainable, environmentally responsible and abundant source of energy.
For decades, the scientific community has been pursuing nuclear fusion, yet now research has reached a critical stage, as scientists are building an experimental reactor that one day may demonstrate that fusion can be used commercially to create electrical power. For more than 50 years, energy has been generated in nuclear power plants through fission, a process in which heavy elements such as uranium are bombarded by neutrons releasing heat in the process.
Nuclear fusion, on the other hand, is based on the opposite principle. In fusion reactors, light atomic nuclei are compressed under intense pressure and heat to form heavier ones and release energy in the process. The process must be optimized to generate more energy than it consumes. With a sufficiently large and sustainable energy “profit”, fusion could be utilized to generate electricity commercially.
The main fuels used in nuclear fusion are deuterium and tritium, both heavy isotopes of hydrogen. Deuterium constitutes a tiny fraction of natural hydrogen, only 0,0153per cent, and can be extracted inexpensively from seawater. Tritium can be made from lithium, which is also abundant in nature. The amount of deuterium present in one litre of water can in theory produce as much energy as the combustion of 300 litres of oil. This means that there is enough deuterium in the oceans to meet human energy needs for millions of years.
Building a fusion power plant that can withstand the immense temperature and pressures this process produces is one of the century´s greatest engineering challenges. The fuel, made up of the hydrogen isotopes deuterium and tritium, must be heated to about 100 million degrees centigrade. At that hotter-than-the-sun temperature, a fully ionized gas-plasma is formed. The plasma will then be ignited to create fusion. At present, scientists are pursuing two methods for achieving nuclear fusion: inertial and magnetic confinement.
In inertial confinement systems, ion beams or laser beams are used to compress a pea-sized deuterium-tritium fuel pellet to extremely high densities. When a critical point is reached, the pellet is ignited through shock wave heating. Fusion power plants using this technique would ignite fuel pellets several times per second. The resulting heat is then used to generate steam that powers electricity-generating turbines.
In magnetic confinement systems, electromagnets are used to contain the plasma fuel. One of the most promising options, the tokamak device, contains the plasma in a doughnut-shaped chamber. A powerful electric current is induced in the plasma, resulting in an increase in temperature. The plasma is also heated by auxiliary systems such as microwaves, radiowaves or accelerated particles. In the process, temperatures of several hundred million degrees centigrade are achieved.
The potential advantages of nuclear fusion energy are manifold, as it represents a long-term, sustainable, economic and safe energy source for electricity generation. Fuel is inexpensive and abundant in nature, while the amount of long-lived radioactive waste and greenhouse gases produced through fusion are minimal.
While research on nuclear fusion continues, many spin-offs relating to plasma physics and fusion technology are already benefiting society. These include improvements in materials research, such as ceramic, metals and coatings, and industrial processes such as welding and waste removal. There are additional fossil fuels available called resources. They are more difficult to re-cover, however. Consequently their price will escalate significantly during the transition from the use of reserves to the use of resources.
In 1994, the world’s rate of primary energy consumption was about 11.6 terawatts (TW), about 87per cent of which was from fossil fuels. At that rate of consumption, the world’s fossil fuel reserves would last about 120 year. However, in spite of effective conservation measures, the energy consumption rate is growing, as developing nations improve their standards of living. At a growth rate of 2per cent in energy consumption per year, these reserves would last only 61 years.
In the coming decades, many new power plants will be required to increase the total capacity for meeting electricity demands, to replace ageing power plants, and to replace fossil fuel plants for reasons related to environmental, health, and cost concerns. Even under the most optimistic scenarios, researchers have projected a shortfall in energy supply by the year 2030 exceeding 5 TW. This is a staggering amount equivalent to 5000 power plants, each capable of generating 1000 megawatts of electricity.
Major non-fossil sources of energy must be developed and deployed to provide more than 10per cent of the world’s energy within the next 40 years. Most renewable energy sources — although making valuable contributions in specific situations — will be inadequate to produce the large quantities of electric power required. Three sources, however, can potentially meet world needs: solar, fission, and fusion. Each has advantages and disadvantages.
Solar energy is diffuse, intermittent, and not suitable for use in some climates, and it is usually expensive. Fission breeder reactors could extend the world’s supply of fissile fuels, but they are not universally welcomed by the public. Fusion reactors could have many desirable features, but much more work is needed to bring them to fruition.
If fusion reactors are successfully developed, as many believe they will be, they could significantly brighten the world’s energy picture. It is also possible to develop a hybrid fusion-fission reactor by putting uranium in the blanket of a fusion reactor, in order to boost the power output and breed fissile fuel. Such a hybrid reactor could have economic advantages, but it would be more difficult to license because of safety, environmental, and security concerns.
The world needs to pursue nuclear power vigorously, to facilitate both the deployment of advanced fission reactors and then fusion reactors before shortages of fossil fuels cause an escalation of fuel prices. Moreover, the nuclear options will have an essential role in counteracting the threat of global climate change that is increasingly being recognized as a consequence of the use of fossil fuels.
Fission power already is partially replacing some carbonbased fuels, and in the future fusion power could be even more attractive. For these reasons, fusion research and development is carried out worldwide in some 40 Member States of the IAEA. The work includes fusion safety studies to ensure that the potential safety and environmental advantages of fusion power will be realized.
BY STAFF REPORTER
The Ethiopian herald May 15/2021
