“Renewable” Energies- the answer to the world’s energy demand?

Eng. Maritza VARGAS
Independent Environmental and Sustainability Consultant
The adjective “Renewable” means that the object or subject in question is capable of being renewed, as contract or an agreement could be. As such, when we hear about renewable energy, we may erroneously think that we are talking about a new type of energy that after use, it renews by itself.
Well, the truth is that what we call “renewable energy” is in fact energy that is generated from “renewable resources” and not that the energy itself is being renewed.

As we all know, the fundamental principle of Conservation of Energy says, in the words of Albert Einstein: “Energy cannot be created or destroyed; it can only be transformed from one form to another”. That is exactly what Renewable Energies do; they use the energy from resources that are naturally energy could be considered clean or alternative, as during their operation they pollute less than fossil fuel powered electric plants do, however, nuclear is non renewable, because the radioactive source comes from finite supplies in a human timespan, just as fossil fuels do.

replenished such as water, wind, solar radiation, geothermal, ocean and biomass to transform it into another type of energy that can be used directly like electricity, heat or transportation. Renewable energies are part of the Clean, Alternative or Low Carbon Energies, but not all of them are renewables. Nuclear Upon REN21 renewables provided 27.7% of the world’s power generating capacity in 2014, accounting for the 22.8% of global electricity production, representing 58.5% of net additions; being Wind, Solar PV and hydropower the dominant markets.”

WATER: Hydroelectric Power

Humans have used hydraulic energy for a very long time. The earliest evidence of water powered wheels back to 300 years BC in Greece; since then, the same principle of hydropower generation has been applied in water wheels (water turbines) using free flowing or falling water to drive mechanical processes such as grinding in water mills, rolling, hammering and other production processes like textile or mining for more than 2000 years from China to Europe and later in America.

Today’s hydroelectric power follows the same principle and is the largest single renewable electricity source, accounting for 16% of electricity generation worldwide (IEA).

The Three Gorge Dam on the Yangtze River is the largest hydroelectric plant with a capacity of 22,500 MW. Through this extraordinary engineering project China has acquired the know-how to build, replicate, and export hydropower plants. Still, the concern lies on the devastating environmental & social impacts of huge reservoirs and theirs consequences.

WIND: Eolic Energy

Wind has also been used for thousands years to power ships, pump underground water and to power machines. Modern wind turbines transform the kinetic energy from the wind into electric energy, basically in the same way that water does it in hydroelectric plants. Wind spins the turbine blades around a rotor that is connected to a main shaft that in turn spin a magnet in side a coil of conductor, known as a generator.

The amount of electricity that a wind turbine can produce depends on four main variables: wind speed, tower height, blade length, and air density. As wind power is not constant and it only works in a certain range of wind speed, methods of storing energy had been developing in the past years; such as batteries and compressed air

Wind energy is clean, free from air and water pollution, competitive and reliable when the natural conditions are in favor. Today’s prices are more competitive than in the past years especially on land wind farms, however in some countries the price reduction is highly due to increment on subsidies rather than as a response of market demand. In some countries in Europe, there is some social concern regarding the visual effect of wind turbines on landscape and the impact on wildlife (birds). There are more than 1,000 MW installed around the world. China, USA and Germany are the countries with most wind power.
SOLAR Energy
Solar energy keeps us alive. It is the most abundant and clean energy source available.

Solar heat technologies are the largest solar contribution to our energy needs and also the most efficient. In some countries the installation of solar water heaters is mandatory for new constructions.
Solar Photovoltaic (PV) directly converts solar energy into electricity. It is extremely practical, modular, with easy and fast installation and it can be used in different scales from rooftop to acres of solar parks. It emits no air pollutants and uses no or little water. The basic building block is the PV cell, which are interconnected to form a module. PV Systems include modules, inverters, electrical components, mounting structures and batteries. A new technology is the concentrating PV that offers 40% efficiency by focusing sunlight into a small area.

Solar thermal electricity (STE) is based on concentrating solar power (CSP) to produce electricity and send it to urban areas. Thermal storage allows generating electricity after the sunset.

The future for Renewable Energy and Climate Change

The “Energy and Climate Change” report published March 2015 by the International Energy Agency (IEA) shows that renewable energy will keep its growing tendency in capacity and cost continue to fall. The Sun could be the world’s largest source of electricity in 2050 with 16% on Photovoltaic (PV) and 11% Solar Thermal Electricity (STE), which could prevent the emission of 6 billions ton of CO2 by 2050. During 2014 the investment renewables remained strong (at $270 billion) accounting for almost half of new power generation capacity, led by growth in China, USA, Japan and Germany.

Global renewables-based power capacity additions by type and share of total capacity additions

Renewables offer a bright future, but it is not enough to cope with the immense amount of energy we need to keep our systems running in a sustainable, reliable, clean and affordable way, while keeping growth in population and economic welfare for all. The answer would be a combination of energy efficiency, changes in current patterns of production and consumption, development and commercialization of Renewable Energies, and the implementation Smart Energy Systems to overcome the fluctuation of renewable energy supply.

Source figures:

  • Fig 1: http://vectorschools.co.nz
  • Fig 2: http://history.alberta.ca
  • Fig 3: http://mechanicalinventions.blogspot.com
  • Fig 5: http://gbdtoday.com
  • Fig 6: http://www.hydro.com.au
  • Fig 9: http://i.ytimg.com
  • Fig 10: “Energy and Climate Change” EIA 2015
  • Fig 10: http://www.energyplan.eu
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