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An important factor in this context that influences technology adoption in MESSAGE are technology diffusion constraints. Technology diffusion in MESSAGE is constraint by dynamic constraints that relate the activity a (level of production) in a period t to the activity in the previous period t-1 (Messner and Strubegger, 1995). Two parameters, an annual increment or startup value s and an annual growth rate r are used to parameterize these dynamic growth constraints. For a period length of one year, the following equation describes the dynamic constraints: 

Without the startup value s, a technology with a zero activity level in year t-1 would not be able to ever reach a non-zero deployment levels, i.e. a non-zero startup value allows the technology to start growing from zero which would not be possible with a purely exponential growth relationship. Therefore, the value of s governs the technology growth during the early stages of entering the market while the growth rates r predominantly constrain the annual growth once the initial deployment is over.