million tons of greenhouse gases
of renewable energy produced,
equivalent to the consumption
of 190 thousand families
in the carbon footprint of energy
production compared to 2015,
aiming at -22% by 2021
Thermal energy produced
MWh 2015 2016 2017
Waste-to-energy plants (51% renewable) 61,054 62,463 79,783
Geothermal energy 73,253 71,733 63,535
Combustion of treatment plant biogas 5,593 4,294 5,985
Total renewable sources 139,900 138,490 149,304
Cogeneration 172,201 174,272 179,250
Cogeneration operated as a service 138,508 153,222 80,873
Total cogeneration 310,709 327,494 260,123
Thermoelectric power stations 252,584 231,607 216,055
Waste-to-energy plants (49% non-renewable) 58,660 60,013 76,655
Total traditional sources 311,244 291,620 292,710
Total 761,853 757,604 702,136

The thermal energy produced from renewable sources increased by 7.8% in 2017 as a result of: (i) the higher energy produced by waste to energy plants, especially in Ferrara (+58% from 2015) as a result of the improvement works carried out (with consequent improvement of the environmental profile, as described in the chapter Air and soil protection) ; (ii) the increase in the production of thermal energy from cogeneration of the biogas produced in the Group’s treatment plants.

The share of energy produced decreased: (i) from cogeneration in service (-73,246 MWh), due to the exit of 4 plants from the company scope by the end of the contract period; (ii) from thermoelectric power stations (-15,552 MWh).

Overall net thermal energy produced by the Group plants, therefore, fell by 7.3% with a change in the mix in favour of energy from renewable sources, due to the above.

Thermal energy produced

Thermal energy produced from renewable sources is equal to 21.3% of total thermal energy in 2017, rising compared with previous years. 37% derives from cogeneration, a high energy efficiency system. Together, the two categories represent 58.5% of electricity produced. 10.9% is energy recovered from waste-to-energy transformation for the share exceeding 51%.