Environmental Problems

Why are environmental problems so important today? In a short period (about 150 years after the Industrial Revolution), the environmental impacts, in terms of magnitude, of human activities became comparable to the ones caused by natural effects. Humans have become a force of geological...

Renewables

What are renewables? Renewables, by definition, are forms of energy that are not exhaustible, as are fossil fuels. All renewables originate in the Sun and will last as long as the Sun itself. Most of them, such as wind, waves, hydroelectric, solar thermal, and...

New Technologies

What is cogeneration? Cogeneration or CHP (combined heat and power) devices allow the simultaneous production of electric and thermal energy in energy systems. They typically recover and use waste heat from a thermal power plant burning coal. These systems are widely used in Eastern...

Fossil Fuels

What are the fossil fuels? Fossil fuels—coal, petroleum, natural gas, and their by-products— account for approximately 85% of the world′s primary energy needs today. Use of these fuels drives industrialized economies and has become an integral part of every aspect of productive activity and...

Energy Sources

Which are the primary energy sources? The world′s energy system is very large: in 2008 it amounted to 492 exajoules, corresponding to 11.75 billion tons of oil equivalent (toe). With a population of almost 6.7 billion people, this corresponds approximately to 1.75 toe per...

Energy: The Basic Concepts

What are forces? In order to live and move around, human beings need to overcome gravity, or the force of attraction that the Earth exerts on all objects. They must also overcome other obstacles to movement, such as friction. With muscular effort, humans manage...

Energy Efficiency

What are the existing technical solutions to the present energy system? Existing technical solutions to the present energy system include higher efficiency, increased reliance on renewable sources, deployment of new energy technologies, and policies to accelerate the adoption of new technologies. These solutions are...

Exhaustion of Fossil Fuels and Energy Security

Are fossil fuels being exhausted? Although fossil fuel reserves are very large, they are, by nature, exhaustible. As we have discussed previously, the expected life of presently identified reserves is 41 years for oil, 63 years for natural gas, and 147 years for coal....

Present Energy Use

How much energy do humans need to keep alive? The daily minimum energy an adult human needs to live is approximately 1,000 kilocalories (1 million calories). A person who consumes less than this amount of energy will lose weight and may eventually die. World...

Energy And Lifestyle

What is the relationship between energy and lifestyles? Broadly speaking, lifestyle is a pattern of daily living that is a combination of values, attitudes, interpretations, preferences, actions, and interactions in a particular time and space. Lifestyle choices are configured by multiple forces: technical, economic,...