**Future Technology Transformations in the Power Sector (**

**FTT:Power)**

**FTT:Power and its theoretical grounding**

It has been known for many years that technology diffusion follows *S-shaped* function, for instance the logistic function, when entering a market, where initial diffusion is slow, then progresses fast, before saturating at high levels of market penetration. This property is an *empirical*finding, but can also be explained with simple arguments, which concern consumer/investor behaviour when they make their choices.

*S*as a variable for the market share, for

**2**technologies, this is described by:

**arbitrary number**of technologies, exchanges between technology

*i*and

*j*can be written as:

*A*contains technology transition time constants (between every possible pair of technologies), while the matrix

_{ij}*F*expresses investor/consumer preferences (e.g. the choice may be 60% of the time for

_{ij}*i*, 40% for

*j,*in which case

*F*60% and

_{ij}=*F*

_{ji}

*= 40%) This is described in reference [1].*

**Use for policy**

**This model is designed for use in policy advising. The goal is to attempt to foresee the impacts of chosen policy. As opposed to many other models of energy systems, the FTT family of models is not a**

*normative*model (finding the optimal technology pathway), it is a

*descriptive*model (predicting its likely evolution). Therefore, in order to find an optimal technology pathway, one would be required to run the FTT family of models many times. While this might appear inconvenient, one must emphasise that the role of policy is to

*incentivise*actors and their choices towards particular directions, and rarely does policy intervene directly. Therefore, even when knowing which technology pathways would be optimal to follow, it is unlikely that policy-makers succeed to actually make the energy sector follow such pathways, particularly when some sectors are dominated by market diffusion (e.g. transport). We therefore expect that, through an important methodological and conceptual contrast to the numerous contemporary normative (optimisation) models of energy systems, the FTT family will generate a useful contribution to current debates.

**References**

[2] J.-F. Mercure, An age structured demographic theory of technological change. 4th International Conference on Sustainability Transitions, Zurich, 2013 (2013).

Preprint available on ArXiv: arxiv:1304.3602

[4] A. J. Lotka, Elements of Physical Biology, Wiliams and Wilkins Company, 1925.

[5] V. Volterra, The general equations of biological strife in the case of historical actions, Proceedings of the Edinburgh Mathematical Society, 6 (1) (1939) 4.