The energy system paradigm

When people think about environmental sustainability and fighting climate change, usually the electric vehicle and renewable energy come to our minds. However, we are missing a huge part of the sources of greenhouse gas (GHG) emissions. Particularly, Bill Gates, who is investing billions of dollars in companies aiming to find cleaner sources of energy, breaks them down into five main categories:

1. Electricity generation: accounting for 25% of the total GHG emissions
2. Agriculture: mainly due to methane emissions of cattle, it accounts for 24% of the GHG emissions
3. Manufacturing: due to energy requirements and byproducts generated, it accounts for 21%
4. Transportation: combining all types of transportation methods (airplanes, ships, trains, trucks, cars, and motorcycles) it sums up to 14% of the total GHG emissions
5. Buildings: all the appliances we have at home creates around 6% of the GHG emissions

(There is around 10% of GHG emissions missing to fill the entire 100%, that are different activities which emit GHG but they account for a lower percentage of the total, and they don’t fit in the previous 5 main categorizations)

Therefore, although many people think transportation is the main reason for climate change, it looks like we are wrong, and electricity generation is the first source of GHG emissions. Accordingly, this article aims to explain how the energy sector works in the specific case of Spain, and then,  whether there is room to improve our performance and reduce our footprint and how challenging it is.

Current offer-demand matching system

Source: https://demanda.ree.es/visiona/peninsula/demanda/total/2020-03-04

This graph shows how a weekday electricity demand looks like in Spain, specifically the 4th of March 2020, with megawatts consumption in the Y-axis, and the moment of the day in the X-axis. You may realize in Spain we start the day between 6 and 9 am, we go to work, and come back home between 6 to 8 pm, and finally go to bed between 10 pm to 1 am. These moments are highlighted because they are when the biggest variations in electricity consumption take place every day, and these variations are the main problems that energy companies have to deal with to match offer and demand. Those variations are also an important reason for the GHG emissions coming from the electricity generation.

For energy companies to both cut costs and reduce GHG emissions, a steady electricity consumption rate would be the best scenario, and that is why they try to shift electricity demand from “peak hours” to “valley hours”. They try to incentivize consumers to make use of electricity at night, so the electricity consumption is higher than it is currently at this moment of the day, and the difference compared with the rest of the day is smaller.

Then, why those daily electricity consumption variations are the main problem and origin of higher costs and GHG emissions?

Sources of energy are divided into two big groups that we all are familiar with: renewable and non-renewable energies.

Renewable energies

Renewable energies come from sources such as sunlight, wind, rain, tides, and waves. They do not emit any GHG while producing electricity (they may do in the production of the machinery needed, and when that machinery used to produce electricity is recycled, reused or destroyed), so they are the cleanest way to produce energy.

Source: https://demanda.ree.es/visiona/peninsula/demanda/acumulada/2020-03-04

This figure depicts the contribution of renewable energies to the entire final electricity consumption. As we may see, renewable energies are a very important component of the total, specifically, it accounts for around 45% on average every day in Spain. Considering the figure shown above for the 4th March 2020, renewable energies account for 55% of the total figure, from which around 70% comes from wind power (green figure), with a pretty constant supply, and 20% from hydraulic power (blue figure). We may notice a significant orange figure as well between 8 am and 7 pm that is solar power yet accounting for less than 5% of the total electricity consumption.

Hydraulic power plays an essential role since we can control it to some degree, working as an energy producer when it is needed, and also as an energy consumer when required, although, of course, we need water to use this system, and shortages of water are becoming more and more common nowadays in many places. This hydraulic energy is used as a controller to adapt energy consumption to energy demand in peak hours, as we may see in the chart above in the blue color.

However, unfortunately, we cannot ask the sun for overtime to get more sunlight and keep producing energy, neither we can ask the wind to keep blowing to move the blades of a wind turbine. Summing up, we mainly cannot control the production of electricity from these sources. Even when we have sunlight, photovoltaic plants may not be able to produce energy if the conditions are not good enough, like it happens in summer when the temperatures are too high. Besides, when the wind blows pretty fast, wind turbines must be stopped to avoid being damaged. Moreover, we neither have suitable electricity storage systems to take advantage of those moments of electricity surpluses thanks to this kind of renewable energies. The graph below shows the data from 12th March 2020, when there was much less wind than in the day shown above, so the proportion of electricity coming from wind power (green figure) dropped to 25%.

Source: https://demanda.ree.es/visiona/peninsula/demanda/acumulada/2020-03-12

Then, with the present renewable energy model, we have zero GHG emissions, but we are not able to supply all the electricity demand we have in Spain. The problem comes when even if we would have an oversized renewable energy system to be able to supply 100% of electricity demand in peak hours, there would be many days in which we couldn’t supply electricity due to lack of sunlight, wind or water storage (mentioning only the main sources of renewable energy). At this point, non-renewable energies come into play.

Non-renewable energies

Due to the dependence on natural factors and weather conditions to get electricity from the renewable sources we now have, access to non-renewable energies is needed. On average, this kind of energy source accounts for around 55% of the final electricity consumption in Spain. As opposed to renewable energies, there is no dependence on weather conditions, there are no such high variations in the electricity production from these sources, and we can control the amount of electricity produced, to some degree.

I just write “to some degree” because we also have dependencies on these energy sources, such as natural resources reserves, where the raw material used to produce electricity comes from.

As a result of the mentioned in the paragraph above, the composition of the total non-renewable electricity output is quite constant, as we may see on the figures shown below from the 4th March 2020 and the 12th March 2020:

Source: https://demanda.ree.es/visiona/peninsula/demanda/acumulada/2020-03-04

Source: https://demanda.ree.es/visiona/peninsula/demanda/acumulada/2020-03-12

It must be said that, although there might be some small differences in the composition of non-renewable energy sources, it is a consequence of the variations of the renewable energies’ electricity generation.

Around 60% of the electricity coming from non-renewable energies has its origin in nuclear energy. This source of energy is clean since there are no GHG emissions on these processes. Nonetheless, with the methods used nowadays, a huge amount of nuclear waste is created and has to be treated later. There are other sources of nuclear energy like thorium, which does not create such nuclear waste, and, besides, it may use nuclear waste as fuel to produce electricity. New developments around this element (thorium) are being carried out nowadays.The main problem nuclear energy presents is that it must have steady electricity production since it is very expensive to shut down these nuclear plants.

The remaining 40% electricity generation from non-renewable energies comes from cogeneration, combined cycle and coal (in that order). These three methods have in common that they create a huge amount of GHG emissions, they are used only when it is needed to match offer and demand, and it is easy and not very expensive to shut them down.

Summing up, the current energy system is formed by around 45%, on average, of clean and weather-dependent energy, and around 55%, on average, of polluting and waste generating energy.

A solution to electricity generation is tough:

• If we maintain the actual energy system, we will keep our high GHG emissions
• If we increase the proportion of renewable energies, with the current technology, we sometimes will need to make use of non-renewable energies
• The increase of non-renewable energies such us nuclear energy using thorium as raw material seems to be a good help, but we still need developments in this field
• The increase of the rest of non-renewable energies is not an option at all

Then, like most time happens in these kinds of dilemmas, nowadays the best option seems to be a balance among them all, with, of course, the highest rate of renewable energies and the lowest need for non-renewable energies.

What it may be said, is that we need to increase (and probably oversize) our renewable energies global infrastructure, either to store electricity with future developments, or to be able to supply electricity (when weather conditions are not suitable for some of the renewable energy sources) with new ways of producing electricity from new renewable energy sources.