Ennio Cardona

Energy saving with MSF-RO series desalination plants

Two major techniques are commercially used in different parts of the world: distillation and membrane processes. The dominant distillation process is multi-stage flash (MSF), and the main membrane process is reverse osmosis (RO). Although cost factors vary by site, the total cost of producing potable water from seawater with the RO process is today usually less than thermal desalting processes and the economic advantages of RO vs. evaporation process, such as MSF, are responsible for the rapid increase in use of seawater RO. In many countries both RO and MSF processes are operating. Reduction in product water cost could be achieved when a hybrid MSF-RO system is used, instead of a parallel system to produce drinking water from seawater. An integrated system for the desalination of the seawater is proposed. The plant is composed of reverse osmosis and multistage flash in series. Electrical and thermal energy are supplied by a cogeneration group for the production of electrical and thermal energy connected to the public net. From a first analysis, the proposed plant seems to allow some simplifications and cost reduction for the fresh water, compared to the equivalent systems in parallel.

ANALYTICAL PREDICTION OF SPREAD SCENARIOS FOR SMALL-SCALE CHP SYSTEMS

In this paper the potential for penetration of small scale cogeneration is assessed at EU level, starting from an overview of the present CHP market. The new EU Directive, representing a milestone in the EU policy for the growth of cogeneration, requires further provisions and large financial efforts to favour increases in the CHP installed capacity and to contribute in overcoming the main obstacles to the spread of polygeneration. Targeting the incentives to all size plants is verified not to be an effective approach, because of the different obstacles to the spread of CHP systems existing in small and large applications. After identifying the main factors influencing the CHP potential in a liberalized energy market, an original index expressing the opportunity for new profitable CHP installations is introduced. Future scenarios for CHP penetration at EU and national level are presented and the expected effects of different policy actions.