One of the biggest challenges facing modern society is energy security: how to guarantee a safe and secure supply of energy in an increasingly networked world where incidents on one side of the planet can have a significant impact on the energy supply on the other.
In the last few years, disputes between Russia and Ukraine over gas pipelines have cut off the supply to parts of Europe. Hurricane Katrina had a significant impact on the energy supply in the US and a terrorist attack on an Algerian gas facility earlier this year reduced the supply to Europe by 10 per cent. In March, the UK was left with just 6 hours’-worth of stored gas as a buffer for the entire country.
These kinds of crises are an inevitable part of the modern world. Preventing them simply isn’t possible. Instead, energy specialist have begun to think about mitigating their effects. The question is: how?
Today, we get an answer of sorts thanks to the work of Rui Carvalho from Queen Mary University of London in the UK and a few pals who have studied how problems in the gas supply cascade through the network of pipelines that carry the stuff across Europe.
They say it is possible to minimise the disruption in most scenarios by routing gas around Europe using the same decentralised protocols that route information across the internet. However, that will only possible with a much greater degree of co-operation across Europe so that pipeline control can be de-centralised in the same way as it is on internet.
The work these guys have put in is remarkably complex. Their first goal was to build a realistic model that simulates the way gas is produced, distributed and used across Europe. That required the fusion of several data sets including the geographical distribution of urban areas and population densities to get a sense of demand, superimposed on the network of pipelines that criss-cross Europe along with their capacities.
Having built the model, the team then simulated crises by removing gas exporting countries, such as Norway or Russia, one by one and seeing how the remaining supply has to be redistributed to meet demand.
The first and most significant effect is congestion. As countries rush to redistribute their supplies, certain pipelines simply cannot cope with the increased flow.
Carvahlo and co say there are three potential solutions. The first is to build more pipelines to add extra capacity to the network. However, this is time consuming, expensive and various plans already exist to improve the network. The team use these plans in their models but make no suggestions about future improvements.
The second solution is to increase the price of gas flowing through bottlenecks to reduce demand. This is how information is routed on the internet–it is essentially free to flow along most routes but the cost of using bottlenecks rises very rapidly.
The final solution is co-operation: dividing the population across Europe into groups with different patterns of demand and finding ways they can co-operate to improve the supply for all.
Carvahlo and co’s approach is to combine the second and third solution. “For congestion control, we are using the proportional fairness algorithm, which is inspired by the way capacity is managed on the Internet,” they say.
This works by allowing the free use of non-congested links up to a threshold but above this, the cost increases steeply. That encourages countries to route gas along the least congested routes
But this is only possible with a distributed method of control–each pipeline operates its own levy which can vary from minute to minute as the flow changes.
That’s fair because no country can hijack the pricing system. And it is more robust than a centralised control system since any local attack only influences that area. “A central controller makes the system vulnerable both to attacks on the control centre and to delays and failures of the lines of communication through the network,” say Carvahlo and co.
The results of these simulations make for sobering reading for some parts of Europe. The countries that cause the biggest disruptions when removed from the network are Russia, a major gas exporter, and the Ukraine, through which most of Russia’s gas has to pass.
Some countries are much more vulnerable to this kind of disruption than others: Macedonia, Estonia, Lithuania and so on.
Even using the new algorithm to distribute gas, replacing the supply when one country drops out can still be tricky. Should Russia drop out, for example, Norway and the Netherlands can take up much of the burden for most of Europe. So many countries that are heavily dependent on Russia can lower the impact of a crisis by adopting the new scheme.
But many countries will still suffer. Carvahlo and co say it is possible to replace up to 50 per cent of the supply for countries such as the Czech Republic and Slovakia but only 20 per cent of the supply to Austria and a measly 5 per cent to Ukraine.
The lesson from all this is that the effects of energy crises are complex and difficult to manage. But the key to reducing their impact is co-operation and this is something that must be organised in advance. “At its heart, energy security, like preparedness for future pandemics, is about cooperation among nations,” say Carvahlo and co. “To avoid European-wide crises, nations must cooperate to share access to their critical infrastructure networks.”
Clearly, this is a time to start co-operating.
Ref:arxiv.org/abs/1311.7348: Resilience of Natural Gas Networks During Conflicts, Crises and Disruptions