When considering alternate energy sources, all stages of the process needs to be taken into account. To translate energy from one media to another, energy needs to be used to allow the conversion. Very often however, rather than direct input a catalyst can be used, to both streamline the conversion, or use a form of energy such as solar, or latent chemical energy. via a catalytic converter, or an organic process. Photosynthesis, and Yeast, metabolism, are examples that involve both. Some of the best catalysts are Enzymes, chemical 'messengers' which can co-ordinate the operation of proteins which are used like an organic 'toolkit'