Comparison of gas turbines and power-to-gas plants for improved wind park energy dispatchability

According to IEA projections for the year 2050, up to 50% of the energy demand in the next decades could be covered by non-programmable sources (e.g. wind and solar power), which can significantly affect power quality, grid stability and power generation planning. Moreover, in several countries a fast growth of installed power based on renewables could not be followed by a simultaneous growth of local grid capacities, leading to increase probability of load shedding events, reducing the productivity of renewable power plants. In this perspective, an important role will be played by technologies which allow improving the dispatchability of non-programmable renewable power plants like wind parks. While a classical approach to grid power modulation relies on gas turbines, an increasing attention is given nowadays to new technologies, not based on fossil fuels, specially focusing on the adoption of energy storage systems. Among these options, one of the most promising relies on the “power-to-gas” concept, which consists in producing hydrogen by water electrolysis and injecting it into the natural gas infrastructure, as currently considered by some research projects and demonstration-scale plants. With respect to hydrogen storage technologies, this option limits the need of a local hydrogen storage reservoir, reducing the investment costs, improving the renewable fraction of gaseous fuels and allowing to oversize the renewable installed power with respect to the grid capacity. In this work a preliminary investigation of the economic feasibility of this system is carried out, starting from the example of the forecasted scenario of wind power evolution in some EU countries. A statistical approach is applied in order to evaluate the error in energy production forecasts. As results, a preliminary sizing of the whole system is proposed, estimating the economic outlook, the possible annual energy and emission balances and the influence of the uncertainty in declared production from wind power plants. A comparison with power modulation based on gas turbines is set up in order to evaluate which are the parameters that influence the economic viability of both solutions, evidencing the different operational criteria of the two systems and their impact on the dispatchability of energy.