Critical Role of Natural Gas in Meeting Electricity Demand with Intermittent Wind and Solar Resources

Natural gas is playing an increasingly critical role in keeping grids stabilized around the world with increasing penetration of intermittent wind and solar powered generation sources.  Even with the advantageous cycling available with natural gas power plants, however, many grid operators are implementing additional grid stabilization strategies including Power Curtailments, Negative Energy Pricing and Electricity Trading, in addition to available hydro pumped storage and run of river strategies.

In 2012, wind powered generation met thirty-five percent (35%) of the generation resources called upon in Denmark, and contributed a maximum forty-five percent (45%) in September.  From a capacity perspective, Denmark's wind turbines hit a capacity level greater than the country's peak requirement, 3.8 GW wind production versus 3.5 GW demand on March 11, 2013.  In order to meet the variable production dynamic associated with wind power, the Danish grid operators implemented a series of tactics, including wide swings in electricity trading, both imports and exports, as well as calling upon dynamic dispatching of natural gas generation resources.  The Denmark grid has six interconnection points with European grids, facilitating their trade in electricity, supporting both system stability objectives and economic objectives.

In Germany, several notable data points have been achieved with solar power and wind power.  On May 25, 2012, Germany hit a peak in solar generation capacity of 22.15 GW, producing 189.24 GWh on that day, contributing fourteen percent (14%) of the country's total electricity requirement.  Germany added 1,008 new turbines in 2012, connecting an additional 2,439 MW in new wind capacity to the grid.

From a recent report by the Fraunhofer Institute, solar power plants produced 27.9 TWh in 2012, reaching a 5% share of the gross electricity production of 560 TWh.  Wind turbines produced a total of 45.9 TWh in 2012, reaching an 8.2% share of the country's gross electricity production.  Accordingly, solar and wind production together 73.8 TWh, representing 13% of the country's total electricity production.

Also from the Fraunhofer report referenced above, the chart below provides details on Germany's electricity production for December, 2012.  One can observe in the chart the excessive variability in renewable energy resources, and the compensating for renewable intermittency by ramping both natural gas and hard coal generation resources, while essentially base-loading nuclear and soft coal resources.

It can be observed that natural gas is lower in the merit order loading for economic dispatch relative to coal and nuclear resources, and is called upon extensively to dynamically balance supply and demand.