Renewable Energy. What, Why, How, And When?

When renewable energy hype is as high as ever, it is quite easy to fall for frequent false information about the subject. You probably think that renewable energy is the invention of the XX or XXI century. However, people have been using renewable energy sources for as long as they have existed without even giving it a second thought. No, I am not saying that Neanderthals have been using solar panels, there are more types of renewable energy than just solar power. So, let’s take a look, what kind of energy sources are considered renewable.

Types Of Renewable Energy

Solar

In common terms, solar energy is harvested by using photovoltaic cells or solar boilers systems to convert sun rays into electricity or use them to heat water. Sun rays themselves are a result of the nuclear fission reaction that takes place in the core of the Sun itself.

Solar energy is a very neat source, however, with current technology we are unable to meet whole planet energy demands just by using energy harvested from the sun. For further read about solar energy, check out this article.

solar energy
Photo by Chelsea on Unsplash

There is one caveat though. The following three of the renewables are dependent on solar energy. So, there are a few indirect ways to harvest solar energy.

Biomass

It’s just a fancy term for plants as an energy source. Also, it is probably the first renewable energy source used by humans. The most common type of biomass as an energy source is wood. Burning wood can be used as a heat source for cooking food or warming up your house.

The downside of such a technology is a quite large amount of CO2 released into the atmosphere and a tree – producer of oxygen destroyed. However, it is not as bad as you think. Carbon in the wood, that is converted into CO2 as it burns, once was CO2 in the air, before a tree “ate” it. Also, if somebody wouldn’t have burned that particular tree, it would have fallen sometime later anyway. And fallen trees, when they rot, also produce CO2. So the carbon cycle happens anyway. It’s just that people can manipulate it to gain some advantage. And if instead of a tree that has been used as firewood we would plant a new tree, it would eventually result in zero carbon emissions.

renewable energy
Photo by Todd Diemer on Unsplash

More modern uses of biomass energy are natural gas production. Rotting biomass material emits methane, which ends up in the atmosphere. But there is a technology for the collection of methane. And methane can be used for heating food or houses.

Wind

It seems kind of self-explanatory. Build windmills – get energy. But these windmills can be built for a variety of different purposes. For example, a couple of centuries ago they were used to grind grain into flour. Also, Dutch used windmills as water pumps on their dams to reclaim land below sea level. Nowadays people are using wind power mainly as a means to produce electricity. Although, wind power requires a lot of land to be efficient.

renewable energy
Photo by Anna Jiménez Calaf on Unsplash

It is worth mentioning that winds are caused by the Sun. Because the sun heats different parts of the planet at a different degree, these differences result in pressure differences that cause the wind.

Hydro (water)

This one also has been used for a long time. Early humans used currents of the river to generate rotational energy that could be further converter as needed. Nowadays, technology changes a bit, but the principle remained the same. Big dams create a lot of water pressure that spins the turbines that spin electricity generators.

As with the wind, this kind of energy is made possible by the sun. As the sun vaporizes water from the oceans and later it rains down to the rivers.

However, the construction of the dams is very expensive and requires a lot of area for the reservoir. Also, the best places for these dams are already occupied.

dam
Photo by John Gibbons on Unsplash

Hydrogen

We all know that hydrogen can burn and emissions are just plain water. There is also a technology called hydrogen fuel cells that can convert hydrogen to water and produce electricity in the process. However, getting hydrogen is quite a challenge. The most common source is just plain water. But a lot of energy is needed to break water molecules apart into hydrogen and oxygen. Of course we could use solar power for this purpose. But in general, the more energy conversions are made, the more energy you lose in the process. Therefore, hydrogen may not be the answer to our energy demands.  

Geothermal

This one is interesting. The core of our planet is much hotter than the crust on which we live. This heat is remains of the accretion of the Earth as well as of some radioactive decay processes that are still happening. As we know, you can use the thermal difference to generate some power. Whether it would be a steam engine or heating of a household, it is possible, if you drill deep enough to reach a significant thermal gradient. Or if you live near a geyser. However, this technology is unavailable in highly mountainous regions due to possible tectonic shifts

geyser
Photo by Peter Gonzalez on Unsplash

When Will 100% Renewable Energy Level Will Be Reached?

In short – probably not in our lifetime.

A lot of countries have highly optimistic plans about reaching 100%, but in reality there are a lot of caveats that are not that easy to solve.

Nonetheless, we know that fossil fuels are causing global warming, and even if we choose to continue to use them, they will come to an end quite soon.  Therefore, we should still put a lot of effort into creating a sustainable energy source.

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