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Renewable Energy Sources: Solar, Wind, and Hydropower


Renewable energy is increasing around the world. This is because energy from fossil fuel becomes scarce. In Indonesia, based on RUPTL 2018, government plant to increase geothermal energy source from 5% in 2018 to 12% in 2025. The percentage of other renewable energy is 0% in 2018 to 2% in 2025.

What is renewable energy? Renewable energy is generated from sources that naturally replenish themselves and never run out.

Renewable energy could be alternative to combat with climate change because it does not generate direct greenhouse gas emission. The only emission that renewable energy generate is indirect greenhouse gas emission, which are from installation, operation, and maintenance.

Renewable energy can also decrease pollution, therefore it gives a little threat to our health. In addition, renewable energy is reliable because it never runs out. Electricity price from renewable energy is also relatively stable over time.

In this post, I want to share to you several energy sources that are very common and also uncommon.

The most common renewable energy sources are solar, wind, hydro power, geothermal, and biomass. The uncommon one are wave power, tidal power, and ocean thermal energy conversion (OTEC).

Solar

Solar power is the most important energy source on earth. It is responsible for our common energy sources. For example, it drives photosynthesis resulting in biomass growing on earth. It evaporates water the water that generates rainfall, and therefore responsible for hydro power, and so on.

Solar energy can be utilized directly to generate electricity. This can be carried out in two ways. The first and the simplest method is to use the heat energy contained in solar radiation as a heat source, collecting the sun’s ray and capturing the heat so that it can be used to drive gas turbine or steam turbine. The second is to produce electricity in solar or photo voltaic cells. The cells can absorbed sunlight and convert the absorbed light energy into electrical energy [2].

Solar energy cannot provide a continuous electrical power on its own because it is only available during daylight hours. For small or off-grid applications, solar cells can be backed up with a battery that is charged during the day.

Electricity generated from solar power is still relatively small. Electricity generated from solar photo voltaic is around 0.85% of global generation in 2013 [2].

Annual Global Photo Voltaic Installed Capacity
Annual Global Photo Voltaic Installed Capacity [2]
Regional Solar Photo Voltaic Capacity as of 2013
Regional Solar Photo Voltaic Capacity as of 2013 [2]
Wind

Wind power is one of three major renewable energy resources along with solar power and hydro power, that are being exploited on a large scale for global power generation. Kinetic energy in the wind is a promising source of renewable energy. The energy generated by wind turbines is highly dependent on local average wind speed.

US department of energy made wind mapping, in terms of wind classes, wind speed, and power density at 50 m above the ground.

Wind class, wind power density, and wind speed classification
Wind class, wind power density, and wind speed classification [6]
Wind developers can use the wind class at a particular site to determine the economic viability of building a wind turbine or wind farm there. Most wind turbines will start rotating when the wind speed exceed 3 m/s, but most wind developers will want a site with a wind class of 3 or above before they will consider it financially viable [6].

Ten largest wind energy producing countries by newly installed capacity in 2017
Ten largest wind energy producing countries by newly installed capacity in 2017 [5]
Hydro power

Hydro power capture kinetic energy of falling water, such as river or waterfalls to generate electricity. A turbine and a generator convert the kinetic energy from water, first to mechanical energy and then to electrical energy using a generator. It is the most used renewable energy in the world. Top hydro power producing countries are China, Brazil, Canada, the US, and Russia [3].

Hydropower Installed Capacity per Region as of 2015
Hydropower Installed Capacity per Region as of 2015 [3]
Because this post will be a bit long, I will divide it into two post. Please look forward for my next post!

I hope you like this post!

[1] Renewable Energy 101

[2] Solar Power Generation by Paul Breeze

[3] Hydropower

[4] Hydropower by Paul Breeze

[5] Global Wind Power Energy Analysis

[6] Wind Power Generation by Paul Breeze

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