Flexibility Needed

As Costs are no longer the Bottleneck for more Renewables, attention shifts to Flexibility

Electric grids do not store energy, so the amounts of energy produced and consumed must match at any time. In the past, it was easy for fossil production to adapt to variations in consumption. As production becomes more weather dependent, it is now more efficient for consumption to follow production and avoid substantial and costly energy storage installations. This is generally called the “Paradigm Change”.

Most energy markets are “Energy Only Markets” with an energy price independent of when it is produced and consumed. Forecasts of consumption and renewable energy production define the schedule of fossil power plants. Short term deviations of reality from prediction are balanced by separate instruments in the control power market, where contracts with large power producers and consumers allow access to and control of their assets to balance the grid.

Unfortunately, as the share of volatile renewable generation grows, such flexibility becomes at the same time more necessary and less available. Sometimes renewable generation even exceeds demand, and energy must be destroyed (shedding).

Demand Side Management improves PV integration

The solution is to use the flexibility that grid users can contribute. Many energy applications do not need to draw energy at night when the sun is not shining: This includes heating and cooling applications, water treatment and pumping, and batteries that power electric vehicles. Here energy can be drawn from the grid only at day time, while their output is available around the clock. This is how the paradigm change is implemented. 

Another possibility is decentral co-generation (CHP) of heat and electricity: operate the plant at night to produce electricity when photovoltaic (PV) energy is not available, and store the heat that is co-generated with the electricity for use during the next days.