Data centers, know your power grid
As we all know the quality and availability of the data center stands or falls with the quality and availability of the power supply to the data center. So data centers are very much depending on the quality and capacity of the power grid, for their daily operations as well for their growth potential.
With a scenario of moderate energy efficiency efforts the energy consumption of EU data centers in 2015 is roughly estimated on 105 TWh coming from a 40 TWh in 2006.
At the same time the European Union is transforming its power grid. That is because the European Union defined some ambitious energy targets for 2020 that aims at:
- 20% reduction of energy usage
- 20% share of renewable energy and a
- 20% reduction on greenhouse gas emission
The EU 20-20-20 goals makes it necessary to update the current power grid and to use a larger percentage of renewable energy. On top of this, the EU has an aging power plant fleet. For the carbon based power plants around 60% are in their second half of their life cycle. And in the next ten years decommissioning of 24% of the EU nuclear power, can be expected. (see this blog entry )
Also several ‘incidents’ at nuclear power plants (Japan, France, Belgium) caused a shift in energy policies of several EU countries and has sent shock waves through the energy industry. Germany’s government announced in 2011 that it would phase out all nuclear power plants by 2022. Recently the government in France reaffirmed to cut reliance on nuclear energy from more than 75 percent to 50 percent by shutting 24 reactors by 2025 (see this article).
Until recently experts were expecting that the usage of variable renewable energy sources would require complex control, coordination and power-balancing mechanisms. Instead of a small number of large power plants in the old power grid, the new power grid will link a larger number of small, decentralized power plants with the consumers. In other words power lines will no longer form star-like networks and linking a few large power plants to nearby consumers, but will look more like a meshed network linking many generators with the consumers. There is a fear that such a dense power grid, with intermittent energy sources, would be vulnerable to power outages because it is much harder to synchronize the many generators and machines of consumers.
A good example of this discussion are the recent power grid developments in Germany.
Renewable energy may stabilise the power grid
In contrast of this, scientists at the Max Planck Institute for Dynamics and Self-Organization in Göttingen have now discovered in model simulations that whereas more decentralized grids become more robust to topological failures they simultaneously become more sensitive to dynamical perturbations.
The simulations indicate that decentralized grids are much more robust when single lines are cut (such as the 2006 power outage around Europe, caused by the shutting down of a single line in Northern Germany). A dense grid can compensate more easily, take the extra load, for a line outage.
The transformation of the current power grid raise the question of where to add new connection lines to the already existing grid. The computer model showed that adding new links may not only promote but also destroy synchrony. Adding new lines can hinder power transmission. This counter-intuitive phenomenon is known as Braess’s paradox. It shows that careful consideration should be given to which nodes can be linked without risk.
The expansion of renewable energy still holds challenges for the stability of the grid. The simulation model showed that a highly decentralized grid is more vulnerable to strong fluctuations in consumption. Large power plants can buffer these fluctuations in demand more easily than small ones, The grid can tap into these spinning reserves at short notice to cover supply gaps, an option which is not available in the case of renewable energy sources.
The Network Dynamics Group based in Göttingen currently starts collaborating with network operators to ensure that their findings can be put to practical use. In the meantime, the research group is improving the model. Their current focus is to integrate weather-related fluctuations in renewable energy sources into their simulations.