RES Scenario in the European Union - The Sustainability of Renewable Energy in Europe - page 38

There are also mini hydroelectric plants which are hydroelectric plants with
a capacity less than 100 kW. The micro-stations fall into one broader category,
called micro-hydraulic by United Nations Industrial Development Organization 3
(UNIDO), a term that indicates hydropower plants with a capacity below 10 MW.
The micro-hydraulics plants are classified as:
• Pico-hydropower plants, P < 5 kW;
• Micro-hydropower plants, P < 100 kW;
• Mini-hydropower plants, P < 1000 kW;
• Small-hydropower plants, P < 10,000 kW.
Both in the case of large and micro plants, the generation of electricity by hydro-
electric presents environmental benefits of not polluting the environment with sub-
stances discharged into the air, as it happens in the case of traditional methods of
generation by thermoelectric.
The micro- hydropower plants mainly solve the problems associated with large
systems: from more parts, large dams are under indictment for the damage they
might cause to natural ecosystems as the variation in the quantity and the quality
of water resulting from the construction of dams can have potential impact on fish
fauna along with any changes in the riparian vegetation.
In many cases, moreover, the micro-hydropower stations have positive effects on
adjustment and retention of floodwaters of the streams, especially in mountainous
areas where they often cause instability and degradation of the soil.
Approximately 20 % of the electricity produced in the world today comes from
hydro. Hydropower in fact contributes to a significant share of the world demand
for primary energy: to a greater extent than 6 % worldwide, but with values much
higher for some regions (e.g. 27 % in the case of Central and South America) or for
individual countries. Global capacity in 2012 amounts to 990 GW, with China ac-
counting for 23 % with 231 installed capacity, Europe for 15 % (148 GW installed
capacity), Brazil 8.5 % (82 GW installed capacity), USA 7.9 % (76 GW installed
capacity), Canada 7.8 % (75 GW installed capacity ) and Russia 4.6 % (50 GW in-
stalled capacity). Globally, hydropower has generated at around 3700 TWh of elec-
tricity during 2012 (Table 2.3 ).
The biomass energy is applied to more than one material, virgin or residual agri-
cultural, or industrial processes, which may occur in different physical conditions.
Depending on the type of biomass and the most appropriate technology for im-
plementing the energy enhancement, there are many different plant solutions.
The plants that are most widely are:
• Conventional, with combustion of solid biomass
• Gas turbine fueled by synthesis gas, obtained from biomass gasification
• Combined cycle, with steam turbine and gas turbine
3 UNIDO is the specialized agency of the United Nations that promotes industrial development for
poverty reduction, inclusive globalization, and environmental sustainability.