What is ‘parasitic’ energy usage and why do tower systems use less?
Parasitic energy is how much electricity the plant itself uses. For example, the pumps and motors of a solar field or receiver are examples of parasitic energy. The biggest use of parasitic energy in a parabolic trough plant is to pump the synthetic oil throughout the heat-collecting pipes throughout the field. Tower systems avoid this costly expenditure of energy simply by not circulating fluid – water – in the solar field. The water/steam circulation pump in a central receiver requires far less electricity, and as a result total parasitic energy usage in a tower system is at least 50% less than in a comparable trough plant. Typical parasitic energy values (including all solar field and heat exchange systems, the power block and balance of plant) are 12% to 14% of electricity produced for parabolic trough systems and 5% to 6% for a solar power tower plant.
