Blog, Green generation & storage

What is green energy and what generation sources does it include?

Did you know that green energy is renewable but not all renewables are considered green energy? This explanation of 100% renewable energy will surprise you

You’ve probably heard, either on a TV programme with some brainy talking heads or on a pretentious Twitter thread, that green energy and its various generation sources is a subject of ongoing debate on which no one seems to agree. If you haven’t noticed this by now –and if so, deep down we envy you–, we recommend that you come out of your bunker and get some fresh air. But first take a look at this post, which will definitely help you in the outside world. Over the last few years, and especially since new sources of renewable electricity generation burst onto the scene, thousands of litres of ink have been spilled trying to clarify what exactly 100% green energy is, and which sources fall into this category.

This is why today, without wishing to err on the side of pretentiousness, we would like to take a brief look at the different renewable energy sources that can be considered green. Because there are some that, although we consider them as such, are not 100% green. Let’s have a look.

The origin of this debate is far removed from the image of those cold power plants we might conjure up in our mind’s eye. Try, for a moment, to erase from your mind those recurring images of cooling towers, solar panels or electric generators churning out watts that run through the grid and into our homes. Instead, take your mind on a more modest journey … to the nearest dictionary. Don’t leave us just yet, you may find this more interesting than it seems.

Let’s begin by defining what green energy is, which is, after all, what has brought us to this point. We can define this type of energy source as one that has no impact on the environment – no pollution and/or degradation of the environment through direct or indirect impact – and whose natural resources for energy production are renewable and inexhaustible for human use. However, it is very important to qualify this definition by pointing to the impact caused by the production and location of the infrastructure necessary for electricity generation. This is a key point, as every human action has an impact on the environment, however minimal it may be. Therefore, we can speak of 100% green energy when we refer to thermal and photovoltaic solar energy, wind energy in its onshore and offshore variants, geothermal energy, biomass and marine energies such as tidal energy –still undergoing research and development, except for the successful case of offshore wind energy mentioned in the previous point–.

Perhaps, at this point, you are wondering what has happened to some of the other well-known types of electricity generation, which you may be surprised not to have seen at first glance. This is very much the case of hydropower, which is classified as renewable but not as green due to its impact on the environment in plants with a capacity of over 10 MW (any smaller than this and they are considered mini-hydro), because of how they can affect river flow. This does not mean that hydropower is not a clean energy resource, but that it cannot be considered 100% green, as it does have a significant impact on the environment. This is the crux of the matter.

Are natural gas and nuclear energy green?

Two sources that frequently make the headlines merit a separate category: natural gas and nuclear power. These two sources for electricity production, which are at the centre of major political discussions –remember that the European Commission has classified investments in these energies as green in order to facilitate the ecological transition and achieve the European Union’s decarbonisation goals– are extremely important for the energy mix of many countries. But let’s take a closer look at the reasons why natural gas and nuclear energy cannot be considered green, despite being clean in the opinion of some experts.

The role of nuclear energy as clean energy is controversial due to the waste it generates as a result of using radioactive material for electricity production. Although those who advocate this source consider it to be clean energy (a view evidently not supported by its detractors), mainly due to the lack of emissions of polluting gases into the atmosphere during the energy production process (it is still a steam power plant, after all), it cannot be considered green due to its impact on the environment. Let us not forget that this is one of the rules for considering an energy as green.

The role of natural gas, while different, has certain similarities. Firstly, natural gas is a type of hydrocarbon and therefore has to be extracted from the earth’s crust, where it has been trapped in pockets under the earth’s pressure for millions of years, and so its extraction has an impact on the environment. In addition, as with other hydrocarbons, it is used to generate energy through combustion, a process that inevitably leads to the emission of greenhouse gases into the atmosphere. Therefore, despite being one of the most eco-friendly hydrocarbons, it cannot be considered a clean energy as such, although it is, like nuclear energy, a very important source of electricity generation with a lower environmental impact.

Well, so much for our modest journey, dictionary included, into the world of green energy. We hope you have found it useful.