**8. Novel resources: hydrogen**

One of the most promising tendencies in clean energy sources is the utilization of hydrogen, which has been identified as the fuel for the energy transition of the

### *Demand Response Applications for the Operation of Smart Natural Gas Systems DOI: http://dx.doi.org/10.5772/intechopen.101810*

21st century by many institutions and scientists as remarked by Cheli et al. [44]. Indeed, mixing hydrogen with natural gas improves the utilization rate of this hydrocarbon while it also reduces greenhouse gas emissions and pollutants [45].

Natural gas and hydrogen may be mixed in the range from 10–20% in order to be compatible with existing natural gas infrastructures [46]. Indeed, in Italy, the gas system operator, Snam, has demonstrated the feasibility of introducing hydrogen into the natural gas pipelines at rates between 5% and 10% [47]. Some experiences have also taken place regarding the metering devices in the natural gas infrastructure, concluding that fractions of hydrogen up to 15% in the natural gas system do neither affect the reliability nor durability of diaphragm gas meters [48].

Hydrogen can be obtained by electrolysis, applying an electrical current. Therefore, this method can be used when renewable energy production is higher than demand during valley periods, which would increase the efficiency of the whole energy system [44]. Such efficiency increment could be maximized by allowing the participation of consumers by means of demand response services, as discussed in the previous sections.
