Sources of electricity – hydroelectric

Hydroelectric power uses height differences and large volumes of water to spin a turbine’s blades and create electricity. Dams can be massive, such as Three Gorges Dam, or smaller, such as those found in mountain rivers.

Dams are highly efficient in converting mechanical energy into electrical energy, efficiencies reaching almost 90%.

Merits of hydroelectric energy are high efficiency, low emissions, relative reliability and additional benefits (flood control, water storage, irrigation). Drawbacks are generation limits almost reached in developed countries, high environmental footprint, disturbance of water ecosystems, siltation (which might limit the life of a dam to 100 years) and unsolved questions on end-of-life dams (Webber 2014; Sheldon 2013)

Sources of electricity – coal

Coal-fired electricity is the most used source to create electricity and, until 2014, it had the fastest growth wordwide (IEA, Coal Information 2015).

Coal forms through the process of coalification, where peat undergoes several changes as a result of bacterial decay, compaction, heat and time. Peat is the plant remains from a water-saturated environment, such as a bog or a mire. This process happens in a water-saturated environment because only in this particular environment there is a lack of oxygen which favours a specific bacterial decay. The degree of alteration of the peat marks the rank of the coal, broadly divided into low-rank coals, such as lignite and sub-bituminous coals, which have lower calorific value and higher moisture levels, and high-rank coals, bituminous and anthracite coals (also known as hard coal), which have more carbon and higher energy content.

Coal mining methods can be either through underground mines: drift, slope and shaft mining or surface-mines: area, contour, mountain top removal and auger mining. Coal mining equipment makes the largest human-built machines on the planet.

Leaving aside other applications from coal, we will discuss how coal is used in electricity production. After coal is mined, coal is taken to power plants through trains and conveyor belts. Coal is then blown in a combustion chamber of a boiler and burned at around 1,400 degrees Celsius. Surrounding the walls of the boiler are pipes filled with water, which are heated to make superheated high-pressure steam. The steam passes through a turbine, causing it to rotate, that turns a generator, creating electricity. Efficiencies of these power plants can reach 46% (EURACOAL, 2013).

In short, merits of coal are abundance, affordability, reliability of fuel supply, easy to store and transport. Drawbacks are land disturbance during mining for surface mines and the release of harmful pollutants during burning.

A few words about energy and electricity – differences

Energy is the basis for modern human civilization, because of the significant increase in productivity it brings. It is a vital part for most, if not all, of human activities: agriculture, communications, trade, manufacturing, mining, education, health etc. Consequently, there is a correlation between energy consumption and wealth (Webber, 2013).

According to the first law of thermodynamics, which says that energy of an isolated system is constant, humans are basically transforming energy that is already in the system into energy more convenient to use. For example, a windmill transformed wind energy into mechanical energy used to mill grain. Replacing human muscle with wind energy increased enormously the efficiency of the process. Repeating this idea for thousand and thousand of processes led to the highly efficient and also highly energy-transformative economy we have today.

For dawns of civilization the main energy source used by humans was wood, later followed by coal and now we live in an era dominated by oil.

There are many forms of energy – kinetic (motion), thermal, chemical, nuclear, radiant (light), gravitational, etc – electricity is just a form of energy, used according to our needs. Electrical conversion is basically a transformation of various energies already existing in the system. For example, thermal energy (heat – which is basically kinetic energy at molecular level) from burning coal; or kinetic energy from wind motion; or gravitational energy from waterfalls is converted into electrical energy.

Energy sources have several classifications. For example, the International Energy Agency manual for energy statisticians (IEA, 2005), which shares harmonized definitions, units and methodology with Eurostat, the statistical office of the European Union, and the United Nations Economic Commission for Europe, considers that energy sources (called “commodities”) can produce primary electricity through direct use of natural resources, such as hydro, wind, solar, tide and wave power or they can produce secondary electricity, using thermal energy as intermediate step, such as from nuclear fission of nuclear fuels, geothermal heat and solar thermal heat, or by burning coal, wood, natural gas, oil, etc.

US Energy Information Administration (EIA, 2015) makes the distinction between primary energy sources and secondary energy sources. Primary energy sources are those forms of energy, such as oil, natural gas, coal, uranium, biomass, wind, that are used to convert energy into energy carriers. Energy carriers, called secondary energy sources, such as electricity and hydrogen, transport energy, which is later converted into other forms of energy that are useful for humans. Electricity is used because it is easy to transport and can be quickly transformed in other forms of energy we need (kinetic, e.g. for coffee maker, thermal, e.g. for light bulbs).

Other several classifications, more or less scientific are used. Conventional energy is used mainly to nominate energy production from fossil fuels, while alternative energy is basically any source other than fossil fuels. Renewable energy is energy derived from processes with a replenishment rate higher than consumption. Eurostat, however, considers biofuels and municipal waste as renewables. Green energy is any form of energy with small environmental impact at its end-use (IEA, 2015; Webber, 2013). However, all energy sources have an environmental impact (Webber, 2014, Sheldon 2014, Mayfield, 2015).

Energy is not the same as power, although similar in meaning. Energy is power over time. For example, a refrigerator has a power of 225 Watts, and in an hour it uses 225 Wh (, 2015), which is a measure of energy.

From a long term energy strategy standpoint, the second law of thermodynamics, which says that entropy always increases or remains the same in a close system, is relevant. This means that Earth-based highly-ordered forms of energy, such as fossil fuels, will always have conversion loses, because Earth is a closed system (Sheldon, 2013; Webber, 2013). For example, overall efficiency for converting primary energy to light using a light bulb is just 1.6% (Tester et al, 2005, p.58). However sun radiance can be used at will, because Earth is not a closed system regarding this type of energy (Webber, 2013; Sheldon, 2013).

In other words, there is a lot of space for progress in energy production.

The adventures of Sherlock Holmes – Arthur Conan Doyle

I didn’t read the book in my childhood, so I read it recently. Interesting, but I read better ones, such as Monsieur Lecoq by Emile Gaboriau. Gaboriau had more depth.

The short stories didn’t allow characters to develop, although Holmes and Watson are in each of them. Also, the stories are more about mystery rather than dangerous crime.

Still, very fluid stories, smart plots, good dialogue. An interesting book.

No easy day – Mark Owen

While there are many accounts and stories about the operation that killed Osama bin Laden, Mark Owen is the real deal. As one of the team leaders that assaulted the compound that night, he tells the story of how the SEAL Team Six killed their number one enemy.

The SEAL operative also describes how the men from one of the most elite units in the US military are constantly challenging themselves to the highest levels of mental and physical endurance.

The main skill they get after the gruesome training is knowing that they can break their own barriers, which makes them confident and balanced individuals. With those skills they can perform at maximum efficiency during combat, when split-second decisions must be made.

Those skills can be noticed when Owen describes the Captain Phillips Operation in the Indian Ocean (a movie starring Tom Hanks reconstructs that operation) and other missions in Iraq and Afghanistan.

The idea that transcends the book and gets to the reader is their mental toughness and ability to act under tremendous stress. It can motivate anyone who wants to push for their own personal desires, particularly in terms of fitness objectives.

I felt really pumped while reading the book and I realized that if you tear down the barriers that you have in your own mind, everything becomes possible.

It reminded me of another book of a SEAL operative “The Lone Survivor”. A SEAL in enemy territory and hunted by dozens of talibans, unable to move his legs due to a spine injury, drew a line in front of him with his knife and cross it time and time again until he got to a village. He drew that line just to push himself to cross it. And he made it, he survived.

Very important for me is that “No easy day” is the real account of the story, written by an eye-witness of the event. It involves no speculations or fantasies, nor is a product of imagination. Imagination is great, but life beats it.