By Michel Gay.
Behind the power socket is a whole world permanently managed so that balance prevails. But it is still necessary to do it by consuming as little as possible fossil fuels that are dearly imported and above all … at all times. Otherwise, it's the cat!
However, it seems that our politicians are not aware.
It is so commonplace to switch on a device by operating the switch so that electricity seems to come out of the socket naturally.
But it is neither natural nor magical.
There are two categories of means of production:
- The "controllable" means that adjust to the demand, it is the case of the thermal productions (nuclear and with flames), and partially of the so-called hydraulic of lake,
- The means "suffered" (or fatal, even intermittent), this is the case of productions (wind and photovoltaic), and partly also a part of the hydraulic said over water.
An electrical system must permanently ensure a production equal to the consumption, whatever its variations. It is called the balance of the network and it has become increasingly difficult to insure since 2009.
The significant development of renewable energies to intermittent productions (wind and photovoltaic) and the slight decline in production controllable from fossil fuels (called flames) are at the root of these difficulties.
The obligation to purchase the fatal production of renewable energies (wind and photovoltaic), associated with their priority of access to the network and their sudden variations, complicate the control of the production system.
Where does electricity come from?
The installed capacity of the fleet increased from 120 gigawatts (GW) at the end of 2009 to 133 GW at the end of 2018.
The nuclear (63 GW) and hydraulic (25 GW) fleet remained stable.
The thermal park with flames is slightly decreasing (from 26 to 19 GW) but the power of gas plants has increased 8 to 12 GW.
Coal has been reduced from 8 to 3 GW (these plants should be shut down by 2022), and fuel oil has gone from 10 to 3 GW.
On the other hand, wind power has increased from 5 to 15 GW, photovoltaics from 0.2 to 8.5 GW, and renewable thermal energies (biogas, waste, biomass) from 1 to 2 GW.
These three sources accounted for 5% (as installed capacity) of the total fleet in 2009, accounting for 18% in 2018.
The growth of renewable energies (+19 GW) did not result in an equivalent decrease in the thermal fire fleet (-7.5 GW).
It is indeed necessary to have permanent power controllable (usually thermal) to overcome their intermittency with a short reaction time, which can especially make gas plants whose fleet has increased by … 50% ( from 8 to 12 GW) in France and 10% worldwide!
But their utilization rate has decreased which results in an overall overhead of the electrical system whose fixed costs must be assumed, even at standstill (personnel, depreciation, maintenance …).
Electricity production already carbon-free
Over the 2009-2018 period, total production (and therefore also consumption) has been stable, particularly since 2010, and the average amount of CO2 emitted has remained low.
It varied according to the years from 37 to 66 g CO2 / kWh thanks mainly to the nuclear industry whose carbon-free production represents 72% of the French mix. The highest emissions in 2016 and 2017 are due to the stops imposed by the Nuclear Safety Authority of some nuclear reactors to carry out verifications.
Hydraulics also has a significant share (12%).
The share of intermittent renewables rose from 1.5% in 2009 to 7% in 2018.
Variations of fatal productions
The sum of the wind and photovoltaic productions illustrated below shows the eminently variable nature of intermittent renewable production throughout a year (2018). Of course, this extreme weather-dependent variability does not match the needs of consumption.
So, " there is always wind somewhere and, thanks to the interconnections, it will always be possible to balance the network Is a misconception.
There are periods without wind (anticyclone) that cover the European continent and, conversely, windy periods everywhere that produce too much electricity that must be "riddled", including paying (negative price) a specialized consumer ! This extra cost for the consumer is still not attributed to renewable energies …
The following two figures illustrate the deceptive effect that the presentation of an intermittent production that varies widely, such as that of photovoltaics for example, can have over a period of 5 days.
The first gives the reality of photovoltaic production with the powers recorded every 15 minutes, while the other presents the daily accumulation that does not highlight the absence of production in the night period.
What lessons can be learned?
The increase in the total installed capacity in France (essentially fatal with wind turbines and solar energy) for constant production leads to an underutilization of the controllable means of production which must nevertheless remain available. This situation weakens the stability of the network, increases CO2 emissions and the overall cost of the system, and therefore the selling price of kWh to the consumer.
The costly terms of purchase obligation and the need to maintain a duplicable system available to mitigate intense production variations, or even their absence during periods without wind and / or without sun … cost more and more to the consumer / taxpayer.
As long as the storage of electrical energy will not be possible at an affordable cost (which may never happen), the use of large intermittent powers is undesirable.
The reduction of fossil fuel reserves in favor of intermittent renewable energies can not be achieved without increasing in parallel the controllable, non-emitting greenhouse gas emissions, which are nuclear and possibly hydro if there are valleys to submerge …
If the government's goal is really to decarbonise energy to meet the COP21 commitments, the priority is to tackle the areas that consume the most fossil fuels: housing and transportation.
It would be ubiquitous to reduce nuclear power to the advantage of renewable energies that use fossil fuels emitting CO2 to offset their intermittency.
Electricity is a virtuous energy vector that can be produced without the emission of greenhouse gases, thanks in particular to nuclear energy. Its use will develop in transport and heating where fossil fuels are still predominantly used.
When your child asks where the electricity comes from, you can now answer it: "Not just taking, darling, not just …"