Work Package 2 examines whether injected and stored hydrogen could undergo geochemical reactions with the rocks and fluids within the storage reservoir and the overlying seal rock. These reactions could prevent the hydrogen from being recovered and used. To understand these geochemical reactions, controlled laboratory experiments will replicate hydrogen injection into porous reservoir rocks at subsurface storage temperatures and pressures to investigate what happens when hydrogen is injected and withdrawn from subsurface reservoirs. We will identify and quantify any chemical reactions to evaluate whether these reactions would have positive (increasing injectivity) or negative (loss of hydrogen) effects on the hydrogen storage. Work package 2 will assess if hydrogen can be securely stored and recovered from porous reservoirs.