SIEMENS

Motorists who venture into the maze of a major city are part of a larger whole. Tens of thousands of vehicles stream along highways from all directions and find their way through a dense network of roads. But keeping that network flowing is no easy task. Already hopelessly clogged under the best of circumstances, such networks can easily face gridlock. All it takes is a few fender benders — to say nothing of circumstances such as a subway strike or a snow storm. As a result, sooner or later, every city government must decide whether to expand its transportation infrastructure or face collapse.

The situation with our power grid is similar. Electricity flows on copper "highways" from power plants to centers of demand. Along the way, it passes through various "road networks" that are separated by substations. These facilities function as traffic lights or railroad switches while also adjusting the electricity before forwarding it to the next grid. In the highest voltage alternating current lines, electricity flows at 220 to 380 kV across hundreds of kilometers from power plants to substations, where the voltage is reduced to 110 kV before the electricity is then fed into the what is called the distribution or high-voltage grid. This grid is used for the general distribution of power to population centers or large industrial sites, where, depending on the region, the voltage is stepped down again to between 6 and 30 kV for the medium-voltage grid. This is followed by local distribution. Here, substations reduce the voltage to 230 and 400 V and send the power into the low-voltage grid, which feeds consumers’ outlets.

Needed: Electricity Highways. Until now, electrons have flown relatively smoothly through Europe’s grids, despite the fact that many of the continent’s power lines are now over 40 years old. Gridlock is inevitable, however, as traffic continues to increase. According to the International Energy Agency, the European Union generated roughly 3,600 TWh of electricity in 2006. This is expected to reach 4,300 TWh by 2030.

In addition, the energy mix is getting more environmentally friendly. In 20 years, some 30 % of the world’s electricity is expected to come from renewable sources. Today the figure is only 17 %. But as the percentage of electricity generated by renewables grows, so does the instability of the network. Because eco-friendly electricity is primarily generated by wind farms (see article "High-Altitude Harvest") much more energy than can be used is pumped into high voltage network in stormy weather, while supply cannot be guaranteed on calm days.

In addition to being able to accommodate a fluctuating supply of wind-generated electricity, tomorrow’s grids will have to incorporate a growing number of small, regional power producers. "The generation of electricity will become increasingly decentralized, incorporating small solar installations on rooftops, biomass plants, mini cogeneration plants and much more," says Dr. Michael Weinhold, CTO of the Siemens Energy Sector. "As a result, the previous flow of power from the transmission to the distribution grid will be reversed in part or for periods of time in many regions." According to Weinhold, our grid infrastructure is not yet prepared for that.

Grid operators and governments agree on how the challenge should be met. In addition to a massive expansion of electricity highways, the grids must undergo a fundamental change. "Right now they are not very intelligent," says Weinhold. "The level of automation for the system as a whole is very low." The low-voltage distribution grid, in particular, is often a total mystery to utilities. Because it includes hardly any components capable of communication in its present configuration, a lot of important information remains concealed, such as the actual amount of energy being used by consumers and the condition and efficiency of the line system.

According to an Accenture study, up to 10 % of energy disappears from the grid either due to inefficiency or electricity theft without being noticed by power providers. In large cities in some developing nations, as much as 50 % of electricity disappears this way, and power providers are often unaware of outages — at least until the first complaint is received.