The document discusses different renewable energy sources and combined heat and power (CHP) technologies for intelligent energy networks. It provides overviews and characteristics of solar energy (photovoltaics, heating, cooling, concentrating solar power), biomass energy, wind energy, geothermal energy, hydraulic energy, and CHP technologies. CHP is defined as an integrated system that produces electricity and thermal energy from a single fuel source. It can improve efficiency and reduce emissions compared to separate thermal and electric production.

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OVERVIEW
 Introduction
– Cogeneration and renewable energy sources for intelligent energy networks
– Renewable energy
– Combined Heat and Power (CHP)
 Theory
– Solar energy
– Biomass energy
– Wind energy
– Geothermal energy
– Hydraulic energy
– CHP technologies
 Exercises
 Business Case
 Summary
Introduction - Theory - Exercises - Business Case - Summary

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Cogeneration and renewable energy sources for
intelligent energy networks
DG is the core logic of smart cities
DISTRIBUITED GENERATION (DG)
Some renewable energy sources are characterized by large discontinuity:
Storage
Grid
Energy efficiency
Cogeneration
Renewable sources
Local production of energy
ICT
Load balance
Introduction - Theory - Exercises - Business Case - Summary

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Introduction - Theory - Exercises - Business Case - Summary
Renewable energy sources have a regeneration time of energy smaller than
(or equal to) time of use.
Therefore fossil fuels cannot be considered as renewable ones.
The renewable ones are:
• Solar
• Biomass
• Wind
• Geothermal
• Water
Energy efficiency (is not a source, but reduces the use of sources)
RENEWABLE ENERGY

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‘... Integrated system that converts the energy of any primary
energy source in the combined production of electricity and
thermal energy (heat) ...’ [1]
COMBINED HEAT & POWER

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Solar is a source => heat, cool, light and electricity
Great potential: In one hour, the sun provides the energy necessary for
the entire planet for a year[2].
Technologies:
• solar heating
• solar cooling
• photovoltaic
• concentrating solar power
SOLAR ENERGY
Introduction - Theory - Exercises - Business Case - Summary

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SOLAR ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Solar heating
100 °C
Temperature
150 °C
Production of sanitary hot water
Heating or preheating working fluids (industrial use)
District heating

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SOLAR ENERGY
• mature technology
• no local CO2 emissions
• silent
• randomness of production
• storage
• variable environmental impact
Introduction - Theory - Exercises - Business Case - Summary
Solar heating: characteristics

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SOLAR ENERGY
Closed-loop systems
• Absorption
• Adsorption
Open-loop systems
• DEC systems(Desiccant & Evaporative Cooling Systems)
Introduction - Theory - Exercises - Business Case - Summary
Solar
collector
Dehumidificationwheel
Heatrecoverywheel
HumidifierHumidifier
Intake
Exhaust
Return air
Supply air
Solar cooling

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• Quite new technology
• High costs for small sizes
• No local CO2 emissions
• Silent
• Randomness of production
• Storage
SOLAR ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Solar cooling: characteristics

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SOLAR ENERGY
Direct conversion of solar energy into electricity.
• High cost of electricity
• Concentration
• New organic materials instead silicon
• Energy storage
• Batteries
• Hot water by Joule effect
• Hydrogen production
Introduction - Theory - Exercises - Business Case - Summary
inverter
End users Grid
Direct
current
Alternative
current
Photovoltaic

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• No local CO2 emissions
• Silent
• Distributed
• Low efficiency
• Only electricity production
• Intermitted production
• Environmental impact
• Land use (agricultural use)
SOLAR ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Photovoltaic: characteristics

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Concentrate the sun's energy in the unit of intercepting surface
• Linear parabolic
• Tower Systems with central receiver
• Linear Fresnel collectors
• Parabolic dish collectors
SOLAR ENERGY
Source: ENEA Quaderno solare termico a bassa e media temperatura
Introduction - Theory - Exercises - Business Case - Summary
Source: ENEA Quaderno solare termico a bassa e media temperatura
Concentrating Solar Power (CSP)
Electrical use
• Thermodynamic
‐ Linear parabolic and Tower Systems
Recent use of molten salts as carrier of thermal energy (high temperature)
Thermal use

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SOLAR ENERGY
Introduction - Theory - Exercises - Business Case - Summary
• No local CO2 emissions
• Silent
• Distributed
• Intermitted production
• Environmental impact (especially for tower systems)
• Land use (agricultural use)
• High temperatures achieved (T up to 550° C )
• Improvement of the thermodynamic cycle
• Need to keep the salts at a high temperature even at night
Concentrating Solar Power (CSP): characteristics

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• Thermochemical processing
• Biochemical transformation
Biofuels: Converting biomass into liquid fuels for transportation:
• colza oil and sunflower oil (biodiesel),
• sugar cane, beetroot, corn (bioethanol).
Biopower: Burning biomass directly, or converting it into gaseous or liquid fuels
that burn more efficiently, to generate electricity.
Bioproducts: Converting biomass into chemicals for making plastics and other
products that typically are made from petroleum.
BIOMASS ENERGY
Introduction - Theory - Exercises - Business Case - Summary

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Biomass
Organic wastes
Forest
Vegetables
Technological
transformation of products
- Food
- No food
Agricultural
- Animals
- Vegetables
Energetic coltivations
Aquatic Land
BIOMASS ENERGY
Introduction - Theory - Exercises - Business Case - Summary
[3] Source: Corso di Impatto ambientale Modulo b) Aspetti energetici prof. ing. Francesco Asdrubali Energia dalle Biomasse

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MAIN TECHNOLOGIES AVAILABLE FOR USE OF BIOMASS
Biomass
Wood
Oil-bearing crops
Glucose crops
Organic waste
Treatment
(mechanics, thermochemical, biochemical)
Mechanics (Cips …)
Gasification
Carbonizzation
Pirolysis
Esterification
Alcoolic fermentation
Anaerobic digestion
Wood
Fuel
Gas
Coal
Oil
Ethanol
Internal Combustion
Engine (Otto cycle)
Internal Combustion
Engine (diesel cycle)
Gas Turbine
Gas Microturbine
Boiler + steam turbine
Technology
BIOMASS ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Pirolysis

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• on demand production
• storage
• CHP configuration
• technology in development phase,
• use of weed killer (for intensive crops)
• environmental impact (from very limited to non-negligible)
BIOMASS ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Biomass: characteristics

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Winds are caused by the uneven heating of the atmosphere by the sun, the
irregularities of the earth's surface, and rotation of the earth.
WIND ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Power
up to 8 MW [8]
Localization
on shore/off shore
Technology
Horizontal and vertical axis wind turbines
Rotor
Breaking system
Tower and base
Overgear
Generator
Control system
Nacelle, yaw system
Fonte: ENEA opuscolo l’energia eolica [4]

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• No local CO2 emissions
• Environmental impact
‐ Noise pollution (sound and sub-sound)
‐ Biodiversity
‐ Visual
• Intermittent production
WIND ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Wind: characteristics

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Geothermal energy uses the earth's heat (steam or hot water at various
temperatures.) [5]
• Vapor-dominated hydrothermal systems
• Water-dominated hydrothermal systems
• Hot dry rock systems
• Sands geo-pressurized
Geothermal energy can be classified according to the temperature of the
fluid
GEOTHERMAL ENERGY
Introduction - Theory - Exercises - Business Case - Summary
High enthalpy heat 630 kcal/kg
(dry steam)
Medium-enthalpy heat 100-630 kcal/kg
(a mixture of steam and water)
Low enthalpy heat 100 kcal/kg
(water at 100 ° C)

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High enthalpy
• Electric Energy
• Industrial steam use
Low and middle enthalpy
• Balneology and spa resorts
• Greenhouse crops
• Aquaculture
• Industrial use
• Drying products
• Other use
GEOTHERMAL ENERGY
Introduction - Theory - Exercises - Business Case - Summary

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Domestic use:
• mature technology
• large power range
• on demand
• reduced environmental impact or negligible
• fluid temperature: 12-15 ° C
• cooling
• heating (with integration by heat pump)
GEOTHERMAL ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Geothermal: characteristics

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Use the potential energy of the water
Different types of turbines as a function of the hydraulic jump
available.
• Pelton,
• Francis,
• Kaplan,
• Cross Flow (Banki)
• Archimedes cochlea
HYDRAULIC ENERGY
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• mature technology
• no local CO2 emissions
• on demand
• storage
• high environmental impact,
• ecosystem damage,
• only electricity production
HYDRAULIC ENERGY
Introduction - Theory - Exercises - Business Case - Summary
Hydraulic energy: characteristics

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The idea of cogeneration is implicit in the Second Principle of Thermodynamics:
• In really feasible and really used technologies, the portion of discarded heat is,
in general, greater than the portion that is converted in mechanical work.
• A generic thermodynamic cycle, addressed to convert heat in mechanical
work, has necessary to discharge a part of heat in input to the cycle.
• Thermal energy is a kind of energy largely used in industrial and civil
applications.
COMBINED HEAT & POWER
• Cogeneration process leads to a more rational use of primary energy with
respect to processes that produces separately the two kinds of energy.
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Plants producing separately electric energy and thermal one can be defined as
Separated Heat & Power (SHP).
A comparison between these two plant engineering solutions can help to
assess the advantages of Combined energy generation (CHP) with respect to
the separated one (SHP)
COMBINED HEAT & POWER VS.
SEPARATED HEAT & POWER
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Chemical
Energy
mcHi
Heat
Q
Work
L
Useful Work
Le
Chemical
pollution
Thermal
pollution
Mechanical
losses
Useful
Heat
Electric
energy
Thermal
energy
CHP Vs SHP
ηmηtηc
Chemical
Energy
mcHi
Heat
Q
ηt
ηc
SHPCHP
Chemical
Energy
mcHi
Heat
Q
Work
L
Useful work
Le
Chemical
pollution
Mechanical
losses
Electric
and
thermal
energy
Useful
Heat
ηmηtηc
COMBINED HEAT & POWER
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A) SPLIT PRODUCTION OF ELECTRICITY AND HEAT
(All figures are energy units)
 = 80/148 = 54%
50
( =80%)
30
( =35%)
Losses = 68
THERMAL
REQUEST
ELECTRIC
REQUEST
+ +
80
63
85
148
INPUT
COMBINED HEAT & POWER
Introduction - Theory - Exercises - Business Case - Summary
OUTPUT

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B) COMBINED PRODUCTION OF ELECTRICITY AND HEAT
(All figures are energy units)
50
30
IN
Losses = 20
THERMAL
REQUEST
ELECTRIC
REQUEST
+
COGENERATION
PLANT
80
100
 = 80/100 = 80%
100
COMBINED HEAT & POWER
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The use of cogeneration systems allows reducing
primary energy consumptions from 15% to 40%,
produced electricity and heat being equals.
COMBINED HEAT & POWER
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• Economically: thanks to plant better efficiency, the energy content of
the fuel can be used in more efficient way.
Further savings can be realised due to local production of energy.
• Environmentally: lower consumption of fuel implies lower
environmental injurious emissions.
• Financially: cogeneration is considered an energy source comparable
to alternative energy sources (sun, wind and geothermal) and
benefits from the legally prescribed incentives and facilities.
COMBINED HEAT & POWER
Introduction - Theory - Exercises - Business Case - Summary
CHP: characteristics 1/2

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• Need for reciprocity between production and demand both for
electric and thermal energy.
• In order that economic convenience could be reached for the
plant, thermal and electric uses have to be near to the
generation system.
• Higher plant costs with respect to traditional systems, due to
cogeneration plant complexity.
COMBINED HEAT & POWER
Introduction - Theory - Exercises - Business Case - Summary
CHP: characteristics 2/2

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Saving can be expressed in mathematical terms as follows[1]:
COMBINED HEAT & POWER
Introduction - Theory - Exercises - Business Case - Summary
 CTHUCELC
C
/Q+/W
F
1=
F
F-F
=ndexEfficencyI
,,

This Efficiency Index and gives an idea of how much energy can be saved by CHP. It
is defined as the ratio between:
• Fc-F: difference between primary energy absorbed by the SHP (Fc)and that absorbed by
CHP (F), being equal the output electrical and thermal energy
• Fc: primary energy absorbed by the SHP
It can be expressed with the second formula where:
• W: is the electric energy in output
• Qu: is the thermal energy in output
• The two η are, respectively, the efficiency of Electric Generation Plant and of Boiler

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Main components
• Engine
• Generator
• Heat exchanger
• Control system
• Distribution system
• Electric connections
• Electric closet (if the company foresee to sell electric energy)
Introduction - Theory - Exercises - Business Case - Summary
COMBINED HEAT & POWER

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 Combined cycle with heat recovery gas turbine engines
 Steam backpressure turbine
 Condensing turbine with steam bleed
 Gas turbine with heat recovery
 Internal combustion engine
 Microturbine
 Stirling Engine
 Fuel cell
 Steam engine
 Organic Rankine cycles
 Any other type of technology or combination thereof falling under the
definitions laid down in Article 3.
Plants that can be defined cogeneration ones [6]
COMBINED HEAT & POWER
Source: ENEA Desire – Net Project
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Comparison among efficiency of different generators
COMBINED HEAT & POWER
MCFC
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Legend
SOFC: Solid Oxide Fuel Cell
MCFC: Molten Carbonate
Fuel Cells
CCGT: Combined Cycle Gas
Turbine
GT: Gas Turbine
ICE: Internal Combustion
Engine
PAFC: Phosphoric Acid Fuel
Cells
PEM: Polymeric Electrolytic
Membrane Fuel Cells
GT: Gas Turbine
MT: Micro Turbine

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Supposing an energy requirement equal to 80 kWh of electric energy and 90
kWh of thermal one, please calculate the consumption variations using a CHP
instead of an SHP.
Data:
• Efficiency of thermoelectric power station equal to 45%.
• Efficiency of thermal power station equal to 95%.
• Cogeneration: electric efficiency equal to 40% and thermal efficiency equal
to 45%
Primary energy saving
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Primary energy saving
SHP
Introduction - Theory - Exercises - Business Case - Summary
Consumption reduction is about 27%
CHP
Electric energy
Thermal energy
Consumed energy (PCI)
80/0,45 = 178 kWh
90/0,95 = 95 kWh
273 kWh
80/0,40 = 200 kWh
90/0,45 = 200 kWh
200 kWh
This has not to be
summed, since it
refers to
simultaneous
production of
thermal and
electric energy

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HIGH EFFICIENCY ENGINES
Which of the following load profiles
is suited for cogeneration?
Chart b
Chart a

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HIGH EFFICIENCY ENGINES
Which of the following load profiles
is suited for cogeneration?
Chart b
Chart a
With use of storage systems

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Practical example
“Hypo Alpe Adria”[7]
Introduction - Theory - Exercises - Business Case - Summary
Trigeneration Plant District Heating and Cooling :
The “Hypo Alpe Adria” trigeneration plant is located in Tavagnacco (UD) in the north-
eastern part of Italy.
In the northern part of the district of Udine, a residential area with several public
and private buildings, including a swimming pool, a hotel, an Italian bank’s
headquarters and other facilities in the service of the community, has been
developed.
The “Hypo Alpe Adria” plant includes a CHP motor engine with 1 MW of electrical
and about 1.3 MW of heat capacity. In addition, two heat boilers with 1.2 and 2.0 MW of
heat capacity have been installed. The cooling plant includes two chillers with 1 MW of
cooling capacity and an absorption chiller with 0.5 MW of cooling capacity.

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Electrical capacity (total) 1,06 Mwe
Heat capacity (total) 1,27 MWth
Technology Motor engine
No. of units 1
Manufacturer Jenbacher
Type of fuel Natural gas
Electricity (yearly generation) 2,37 GWh
Heat (yearly generation) 2,57 GWh
Year of costruction 2006
Total investment cost € 2.800.000
Financing Own funds
State support Certificates, tax reduction
Location Tavagnacco,Italy

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 Some renewable sources present strong production discontinuities.
 It becomes necessary to adopt energy districts (that are local industrial
zones with local production, exchange and consumption of energy) for
optimizing and using produced energy.
 CHP systems represent a way to make efficient use of primary sources
when both electric and thermal energy are needed.
 CHP systems can be fed also with renewables sources (biomass).
Repetition
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Readings
 [1] AEEG (2002) n. 42/02 19 March, 2002
 [2] www.roma1.infn.it/rog/pallottino/bacheca/Sole%20e%20rinnovabili.pdf
 [3] Corso di Impatto ambientale Modulo b) Aspetti energetici prof. ing. Francesco Asdrubali Energia dalle
Biomasse
 [4] Opuscolo ENEA ENERGIA EOLICA
 [5] Francesco Zarlenga - ENEA [2011] EAI Energia Ambiente e Innovazione 3/2011
 [6] European Parliament [2004] Directive 2004/8/EC on the promotion of cogeneration based on a useful
heat demand in the internal energy market and amending Directive 92/42/EEC
 [7] CODE PROJECT IEE – Cogeneration Case Studies Handbook
 [8] http://www.vestas.com/en/products_and_services/turbines/v164-8_0-mw#!at-a-glance
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Pictures -1
 Slide 15 – ENEA Quaderno solare termico a bassa e media temperatura
www.enea.it/it/enea_informa/documenti/quaderni-energia/solare.pdf
 Slide 21 – ENEA Opuscolo l’energia eolica
old.enea.it/produzione_scientifica/pdf_op_svil_sost/Op19.pdf
 Slide 38 - ENEA Desire – Net Project
www.desire-net.enea.it
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