**2. Development of New Empirical Models for Gasification**

The empirical models are developed here relating to a number of inputs (*x*) to predict some output value (*y*ˆ) as shown in Figure 1. If there are multiple outputs to be predicted, then regression models can be developed separately for each. For the case of gasification, the exact input values used depends on the gasifier design and the available data but will generally include the moisture and the elemental composition as well as the air- or steam-to-biomass ratio (or equivalence ratio). Based on these inputs, various different linear or non-linear expressions can be proposed relating to inputs with outputs which might typically include the product gas composition, gas yield/production rate etc.

**Figure 1.** Simple schematic of a regression model used to take inputs (*x*) and calculate a predicted output value (*y*ˆ).
