Balancing the grid loads by large scale integration of hydrogen technologies: The case of the Spanish power system

This paper deals with the potential of power generation resources for hydrogen production and electric grid load balancing in large scale management scenarios like the Spanish power system; much of which is currently underutilized and could deliver substantial amounts of energy, with great advantages for the reliability of the system at the same time. In this context, the production of hydrogen by electrolysis using the power grid mix is a promising option as an alternative to other operational procedures or exporting the electricity. Power generation can be controlled by the disposability of the installations and their utilization ratios; thus, we analyze the forms of generation to shape the power load curves, by using the regulation with hydrogen and getting a balance of efficiency, economy and ease of operations. To estimate hydrogen production we use the characteristic curves of electrolyzers, where the interest is that it applies to variable operations with time: i.e. the 'surplus energy' during over-generation periods is electrolyzed into hydrogen, which can be reconverted into electricity for 'peak shaving' or other uses. We establish a 'critical ratio', which determines the power generation for given demands, to fulfill the needs of the electric grid according to the curve profiles and the regulation with hydrogen; this ratio depends of many variables which are investigated for reaching an adequate balance: the energy gap of the generation and load curves, the capacity factor of the electrolyzers with regard to their maximum power inputs and the shape of daily generation curves. The resulting scenario is good enough for the transition of power system, as it admits 42% of energy from decarbonated sources, at the same time that shortens the payback period of fossil fuel utilities and generates hydrogen for other uses; economically, we obtain a positive cash-flow of the project after the third year, while the net incomes are 1863 M in the whole period; environmentally, it reduces the emissions from 236 to 210 kg(CO2) per MWh(e), while we can fuel three millions of hydrogen vehicles, with a net reduction of 4 Mton(CO2) and local air pollutants. After ordinary thermal installations are amortized, the management with hydrogen at large scales would permit the deployment of the power systems based in renewable sources, doing away with all CO2 emitting technologies which are substituted by wind, solar, hydro or nuclear. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.