I will try my hand at a basic science blog tackling complex and controversial issues like Energy and Climate. As a practicing Geophysicist I have had plenty of exposure to these areas. My basic tenet is to be as even handed as I can and explain the science in simple terms. This does have the problem of being a bit loose with scientific terms, inevitably attracting criticism. Getting lost in detail and scientific jargon will lose the simplicity.
In Physics, Energy is the ability of a system to do work. Energy is neither created nor destroyed. It is however readily converted from one form to another or from matter to energy and vice versa. Common forms of energy are motion (kinetic), gravity (potential), heat, chemical, nuclear, electrical etc.
This definition of Energy means it can always be measured or calculated. One way to do this is by converting everything to heat units (eg calories). For example running one kilometre burns about 60000 calories. One gram of sugar consumed provides about 4000 calories.
Out of the fuels that might provide us energy the heating ability is:
|Source per gram||Energy (in cals)|
|Water||0||Does not burn. No energy content|
|Nuclear||19 000 000 000||Nuclear reaction not chemical|
|Solar||1 200 000||maximum possible per sq m per hour|
|Solar||120 000||maximum generally collected per hour|
(Note that the official measure of energy in the metric system is the Joule where 1 cal = 4.2 Joules)
(1000 cals = 1 kcal and is sometimes referred to as 1Cal or large Cal)
Water does not burn and therefore has no chemical energy. Hydrogen can be extracted and burned but it requires more energy to extract the hydrogen than is gained by burning. Hydrogen, from water can be used in a fusion reaction to convert its mass to energy. Water maybe a catalyst in some reactions to obtain additional energy.
If it can not be measured, it is not considered Energy in science. This includes psychic energy, Chi, Reiki energy, ghosts etc. These are concepts which can not be tested or measured to a level accepted as science.
Other useful concepts are:
Power is the rate of using energy ( measured in watts)
Mass can be converted to Energy in nuclear reactions E= Mc2 (where c = speed of light). That is Energy = Mass * Constant
Available Large Scale Energy
The Earth is not a closed system. It is continually bombarded with external energy, principally from the sun. It is also continually losing energy to space. Additionally the Earth is heated by nuclear reactions within its core (Geothermal energy).
Available energy can come from a variety of sources generally broken down to:
Solar / Lunar
- Direct solar
- Wind (onshore / offshore)
Radiation from the sun (energy from nuclear fusion reactions) and gravity from the sun and moon provides the energy in each of these instances. Once buried wood, plant and animal remains become fossil fuels
- Natural Gas (methane)
- Natural Gas liquids (ethane, propane, butane)
- Oil (Petroleum, Diesel, Avgas)
- Heavy oil (pitch, tar sands)
These are products which result from the burial of organic material.
Nuclear / Geothermal
- Fission (converts heavy elements to lighter elements releasing energy)
- Fusion (converts light elements to heavier element releasing energy)
- Geothermal (heat released from natural fission reactions within the Earth)
All of the controlled, artificial Nuclear energy produced is from fission reactions using Uranium and possibly Thorium. Artificial, controlled Nuclear fusion to provide large quantities of power is still some way off.
Energy can also be stored – generally as chemical energy (batteries, fossil fuels, biofuels, hydrogen, etc), potential energy (hydro water, flywheels, springs, compression etc) or heat. Any energy source can be converted to electrical energy for use in homes, industry and transport. This needs to be used immediately or otherwise stored.
Pumped hydro is storage of the energy used to pump. This can not be hydro (it would be a waste of energy as less energy is stored than used). If coal is used to pump the water then it is stored coal. If solar is used then it is stored solar.
Each of these energy sources and storage systems will be discussed in future blogs.
When comparing Energy usage – by country for example it is worth keeping in mind total Energy use. All countries have a mix of energy sources providing energy for a variety of needs. Domestic electricity is often a small part of the energy use with heating, cooling, cooking, farming, mining, transport and industry often provided for from other sources. Gas for cooking, oil products for transport, geothermal for heating are obvious examples.