In Belgium, electricity peak load can reach up to 14 GW , while base load  can be as low as 6 GW . Historically, large gas power plants have provided much of the flexibility needed to handle these variances.
The efforts to increase the share of electricity generated by renewables (RES) has however reduced the operating hours and profitability of flexible gas power plants. This is resulting in the closure of flexible power plants.
Today, in Belgium, the renewable intermittent  energy sources (wind and solar) are responsible for about 11% of the total electricity production. This is not sufficient to destabilise the electricity grid, but it is estimated that wind and solar power capacity will increase from 5.77 GW in 2015 to 8.84 GW in 2020 .
So, during periods of high demand, and when there is no wind or sun, the risk of supply shortage will increase.
From a medium-term perspective, there are 4 types of solutions for tackling the decrease in flexible gas power plant capacity and thus prevent supply shortage problems during peak demand:
- Adapt production:
- Increase the profitability of flexible efficient gas power plants by introducing capacity remuneration mechanisms.
- Increase the flexibility of must-run power plants, such as Combined Heating Power plants (CHPs). CHPs run first of all when there is a need for heat – the electricity they produce is a side product. When there are peak electricity loads, one can also activate the CHPs that do not need to supply heat and store the heat that is generated.
- Adapt consumption:
- Decrease consumption via rational energy use and energy efficiency, which will decrease peak demand as well.
- Make consumption follow production by increasing flexibility on the consumption side.
- Increase import
- Create energy storage capacity
Most probably a mix of the above solutions is needed. In the paragraphs below, we look at the evolutions in the energy storage domain, as a big project in this area might get underway in Belgium.
The number of projects related to energy storage has risen sharply during the last few years. Today, energy storage technologies exist at many levels of development – from the early stages of R&D to mature, deployed technologies . The storage systems currently installed in electricity grids worldwide have a capacity of at least 140 GW. The vast majority (99%) of them are comprised of pumped storage hydropower (PSH). In Belgium, the Coo-Trois-Ponts hydroelectric power station has a capacity of 1.164 MW. The other 1% of storage technologies includes a mix of battery, CAES, flywheels, and hydrogen storage.
In Belgium, the THV iLand consortium has submitted a request to build an energy island, 5 km off the coast of De Haan. The energy island applies the principle of pumped storage hydropower. If the Belgian government approves this project, it will be the first energy island of its kind worldwide.
The energy island will be able to supply 550 MW for almost 4 hours. When electricity prices are low, water will be pumped from the energy island into the sea; when electricity prices are high, water from the sea will be pumped into the energy island, generating electricity. It is estimated that the investment cost will be about €1.3 billion and the annual operational cost about €5.6 million . If approved by the Belgian government, the energy island could be operational in 2021.
This energy island will certainly not solve the entire Belgian energy supply problem – but it seems clear that it will contribute to the evolution towards a low carbon emission energy supply system and support the security of supply.
For more information regarding this article, please contact: Frank Sels at firstname.lastname@example.org
Authors: Alexander Cappelle & Alex Curtoud
 Maximum historical peak load occurred on 17 December 2007 (14.033 MW) – source Elia system & market overview 2012
 “Base load requirement is the minimum level of demand on an electrical supply system over 24 hours” – source Wikipedia
 Minimum historical base load occurred on 22 July 2012 (5.845 MW) – source Elia system & market overview 2012
 “An intermittent energy source is any source of energy that is not continuously available due to some factor outside direct control” source Wikipedia
 ENTSO Scenario Outlook & Adequacy forecasts 2014-2030 Dataset BE
 See Figure 2: Maturity of Storage Technologies
 Source: De Tijd