Tuesday, January 08, 2013 | Sjef van Gastel, Assembléon Netherlands B.V.
Editor's Note: This column originally appeared in the December 2012 issue of SMT Magazine.
I was recently driving through Germany and was surprised by the huge number of solar panels on house roofs--even in the smallest villages. Approximately 5.3% of all energy in Germany is solar, with a total installed capacity of 29.1 GW (20 conventional power plants). Other sources of sustainable energy in the country include wind, biomass, geothermal, hydropower, and biogenic fuels.
In 2012, more than 20% of all power in Germany is renewable. In May 2011, government officials announced a plan to shut down all nuclear reactors by 2022. Physicist Amory Lovins remarked, “Chancellor Merkel was so shocked by the Fukushima disaster that she turned Germany’s focus from nuclear to energy efficiency and renewables. That’s supported by three-quarters of Germans and opposed by no political party.”
Impact on Power Grid Design
This sustainable energy revolution will have great impact on how the power grid is designed and operated. In a classic power distribution grid, all power is generated in a limited number of large-scale power plants and consumed by industry, transportation, offices, public institutions (including street lights), and households. Power generation is large scale and separate from power consumption locations. Transportation, conversion, and consumption are designed for one-way energy flow. Energy meters also register one-way energy consumption.
Renewable energy instead combines multiple, decentralized power generation points with multiple, decentralized power consumption points. To make this even more complex, power generation and consumption points should switch instantaneously, depending on weather conditions and energy consumption needs.
I visited the Econexis house, a demo house for smart grids, in Zwolle, the Netherlands. Built on a beautiful green-lined plot behind the main office of grid administrator Enexis, the house demonstrates what is possible for energy conservation and generation in a private home. The house is covered by nearly 100 square meters of solar panels, and uses geothermal heating and cooling. Moreover, the “waste” heat from, for example water used for showers and washing machines, is not flushed away with the sewage, but passed through a heat exchanger for house heating.
Much of the time the house can be heated and cooled in an energy-neutral way and often generates considerably more electricity than it consumes. That surplus electricity can be stored in the batteries of the electric car, in a separate battery energy storage system (BESS), or fed back into the (smart) grid so no overcapacity is lost. An energy computer recommends the best time of the day for the owner to switch on large, energy-consuming appliances like the washing machine and dishwasher. When there is not enough wind or solar energy, the house switches automatically to conventional power as generated by a large-scale power plant.