Intro to cogeneration
Among the most used low environmental impact technologies, cogeneration has undoubtedly taken a relevant place in the energy industry. Although they fall outside the field of renewables, cogeneration systems are raising great interest in the perspective of environmental safeguard.
Co-generating literally means producing two or more forms of energy, usually electric and thermal energy from a single energy source. Cogeneration systems are also called Combined Heat and Power, from which the acronym CHP derives.
Electricity and heat
Electricity and heat are usually produced separately. As a matter of fact, electric energy is generated by thermoelectric power plants, which disperse heat in the environment during the cycle of production. On the other hand, thermal energy is provided by furnaces which convert fuels into heat. More specifically, electricity is produced by thermic engine plants in which heat, through a thermodynamic cycle, is converted first into mechanical energy and then into electrical energy throughout electric generators. In this transformation process, heat is not entirely transformed into “work”, a part is discharged. It is precisely this portion of heat that is not exploited to be regained through cogeneration.
Advantages of cogeneration. Image courtesy of Inoplex.
A brief history of cogeneration
Historically, during the early decades of the 21st century, cogeneration was broadly used among small and large industries because of shortage of available resources. With the expansion of large electric power plants and the subsequent development of more reliable stations and distribution systems, industries began to consider buying electricity as more cost-effective, thus only focusing on producing heat.
In the recent years, some factors such as the increase in power costs, economic expansion, global competition and environmental concerns represent the major reasons for industries to turn to cogeneration again.
CHP systems can be powered using several kinds of primary energy: through fossil-delivered material such as natural gas, diesel, fuel oil, coal; through refuse-delivered sources such as solids or biogas from landfills or purifiers and through biomass such as wood chips, agricultural and forestry waste.
The pros of cogeneration systems
The advantages of CHP can be grouped as follows:
- First, it lowers the consumption of primary energy, since fuel can be used to produce both electricity and heat. The decrease in consumption is allegedly in the order of 35% – 40%.
- Second, it lowers the emission of pollutants. In the perspective of carbon emissions, optimization of fuels results into a lower consumption of non-renewable sources. Every ton of fossil fuel we avoid burning stops carbon dioxide from entering the atmosphere and reduces, partially, the problem of global warming.
- Third, cogeneration technology is widely available and implementable, with further opportunities for development and refinement.
- Last but not least, lower primary energy consumption means lower production expenses. In fact, in traditional heating systems, most of the energy produced by combustion (about 60%) is lost in the form of heat. Only the remaining part (30-35%) is actually used. In a cogeneration plant, however, this heat is recovered and converted again into thermo-electric energy ready for use.
Although the many valuable positive aspects, cogeneration systems reveal some tricky aspects. What are the challenges for software producers to adopt reliable solutions for control and monitoring? They will be accurately sifted in the next article.