Cogeneration: find out a little more

How does Cogeneration work?

Typically, in a thermal power plant, only about 35% of the fuel is converted into electricity. The remaining 65% is not used and ends up dispersed into the environment as thermal energy. So why not recover it? This is the fundamental principle of cogeneration: a single plant produces double the energy, based on re-using one of the two parts that would otherwise be wasted.

Cogeneration takes place at special thermal power stations. It involves the recovery of hot water or process steam produced by a prime mover powered either (unfortunately) by a fossil fuel (natural gas, fuel oil) or by non-fossil organic fuels (biomass, biogas, synthetic gas). In this case, significant energy savings are achieved compared to the separate production of electricity and heat.

Advantages

Several positive aspects are associated with the cogeneration of thermal energy and electricity using a single plant:

• Environmental: reduced air pollution and less dependence on fossil fuels;
• Energetic: energy savings, lower fuel consumption, higher energy efficiency;
• Economic: lower costs, government incentives.

Mini-cogeneration

The widespread production of electricity and heat by small-scale generators powered by renewable sources represents a significant change in the cultural and technological model that has determined the expansion of the energy system, historically based on centralized electricity generation.

Today, this model is undergoing a major transformation with the widespread use of small and medium-sized generation plants, especially the cogeneration type (combined production of electricity and heat) aimed at achieving a more rational use of energy while reducing CO2 emissions into the atmosphere. These technologies now provide a new opportunity in contexts where agricultural or forestry resources and large quantities of various types of waste are present.

Investment and incentives

Investment in mini-generation plants leads to important business benefits for small and micro enterprises: it allows them to diversify their business and make a profit by feeding electricity into the grid at a government-subsidized rate. Moreover, in producing thermal energy an enterprise and nearby business and residential users can achieve energy autonomy.

CASE HISTORY

Saving on energy and heating costs with a micro-cogeneration plant

The plant not only saves money but is also flexible in terms of fuels and easy to run.

These are the qualities of the mini-cogeneration plant installed by Uniconfort, thanks to a partnership as the general contractor of Termogen of Pisa, at the new Santa Croce sull’Arno (PI) plant owned by Dermochimica in Agrate Brianza (MB), a company that produces chemical products for treating leather.

This plant is tailor-made for companies that have limited needs in terms of heat and energy production, but also want to reduce their energy bill and make a green choice.

A Global boiler, which uses ORC technology for the cogeneration of thermal energy and electricity, has been installed. It simultaneously generates 700 kW of thermal energy, required to heat water to 55-80°C, and 165 kW of electricity. The thermal energy generated is used to heat the premises, whereas the electricity is sold to the grid.

The Global boiler, like all Uniconfort boilers, is the only one on the market that uses woodchips with high humidity (up to 55-60%), which are more readily available on the market and cost less. This avoids having to use only high-quality woodchips, thus increasing savings for the company.

With this new technology, Uniconfort enters the market for plants with a burnt power of less than one MW. They are particularly subsidized by the “Conto Energia” (FIT renewable energy) incentive, and are not burdened by complicated authorization procedures.

The plants in numbers

• Global boiler: burnt power ≤ 1 MW
• Total Electric Power: 165 kW
• Residual heat: 700 Kw
• Woodchips: 55-60 % umidità