Trigeneration. Is the generation of electricity, cold and heat possible at the same time?

The answer is yes. Let’s start by defining what is the trigeneration: it is a system or process set in wich cold as well as electrical energy and heat (typical of cogeneration) is generated, all from the same fuel or the same primary energy source, and the electricity generator is located nearby the users.

The traditional way of obtaining these energy products is separately, that is, electricity ussually comes from the grid or electrical system, heat is produced through fossil fuel burners and cold from vapour compression cycles through electrical consumption. The trigeneration systems have economic and environmental advantages campared to the conventional generation form, among them, savings of primary energy and greenhouse gas emissions reduction both of them leading to higher global thermal performance. There is a variety of primary energy sources that can be used in trigeneration systems such as fossil fuel burning (i.e. Natural gas), renewable energy or even waste heat from industrial processes, the last two adding even more environmental benefits. On a renewable primary energy source,  the production of electricity, heat and cold can be independent of the electricity grid and the consumption of fossil fuels, reducing the external requirements of the system and providing reliable supply of energy to the users. There are trigeneration facilities that use biomass, solar thermal energy, geothermal energy, and even combinations of several of them are common. Diverse types of technologies are applicable to the electricity generation: steam cycle (rankine cycle and organic rankine cycle), gas turbine, internal combustion engine, among others. The selection of one or other technology depends mainly on the amount of electrical power to be provided and on the available primary energy source and its featurings.

The venezuelan company Servicios Integrales de Proyectos, C.A. (Servinproca) is pionnering in to providing solutions to hiden customer’s needs, taking the responsibility to carry out the following proposal to one of the many energy requirements in our region through the project: «development and implementation of orc solutions (organic rankine cycle), trigeneration units [electricity, cold and heat]». The organic rankine thermodynamic cycles (orc)  use low temperature level primary energy sources and specific organic working  fluids instead of water, used in plants of traditional steam generation. The orc systems are characterized by its simplicity in terms of their equipment configuration compared to other cycles that have similar purposes, aspect that makes it competitive in both economic and technical matters.

Some of the cro solution advantanges are the following:

• Electricity can be generated using low temperature heat sources being the working fluid (organic substance) temperature below 90 ° c.
• High performance. Due to the use of high volumetric mass fluids, electric power can be generated efficiently even for small power levels.
• Electric power level range between 5 kw to 3 mw.
• Efficient at partial load opertation between 30% and 100% full load.
• zero fuel consumption equipment (depending on the primary source of energy) and zero emissions.
• It does not require a velocity reducer to drive the electric generator; hence the mechanical losses are almost nil.
• Due to the organic fluid properties, and the fact that operates in a cycle, no corrosion occurs, and the system does not loose working fluid, except due to accidental leakage.
• Great performance, between 95-98%. (25-30% electric, rest thermal).
• Low environmental impact: non-toxic, non-corrosive, non-flammable.
• Low noise, compact and low maintenance.

In summary, this technology is based on the use of energy, which would otherwise be wasted or not used, reducing costs in case of production plants or increasing benefits in case of power generation systems.

The servinproca challenge is in the integration between the primary energy source and the orc system in a single module or equipment to generate these energy services (final result), adapting the existing orc technology with a view to reducing investment costs , through the manufacture of parts in the local market and working in the various uses of this technology with different heat sources, developing a solid and feasible solution in several applications.

On november 2nd of this year, the project kick off meeting was held at the servinproca offices (www.servinproca.com), led by its president ing. Angel araujoprimera and a group of high credentials professionals, they took on this commitment with a deep sense of conviction, aiming to develop solutions with a national workforce and conceptualization and making professional quality contributions to our local communities and abroad.

Autor: Ing. Mec. Ángel Araujo P.

Revisado por: Prof. Numa Marquez, PhD.