SESEC Training Module 5: Renewable Energy and co-generation

Co-funded by the Intelligent Energy Europe Programme of

the European Union 1

Renewable energy &

cogeneration

Introduction - Theory - Exercises - Business Case - Summary



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



the European Union 3 Introduction - Theory - Exercises - Business Case - Summary

Introduction



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

UrbanRuralCustomer loads

Industrial

Cogeneration

Renewable sources Local production of energy

ICT

Load balance




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



‘... 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



Theory


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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




SOLAR ENERGY


Solar heating

100 °C

Tem

pera

ture

150 °C

Production of sanitary hot water

Heating or preheating working fluids (industrial use)

District heating



SOLAR ENERGY

•mature technology

•no local CO2 emissions

•silent

•randomness of production

•storage

•variable environmental impact


Solar heating: characteristics



SOLAR ENERGY

Closed-loop systems

• Absorption

• Adsorption

Open-loop systems

• DEC systems(Desiccant & Evaporative Cooling Systems)


Solar energy

Solar collector

Deh

umid

ifica

tion

whe

el

Hea

t rec

over

y w

heel

Hum

idifi

erH

umid

ifier

Intake

ExhaustReturn air

Supply air

Solar cooling



•Quite new technology

•High costs for small sizes

•No local CO2 emissions

•Silent

•Randomness of production

•Storage

SOLAR ENERGY


Solar cooling: characteristics



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


Solar energy

Solar

cells

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


Photovoltaic: characteristics



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


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



SOLAR ENERGY



• 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



• 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




Biomass

Organic wastes

Forest

Vegetables

Technological

transformation of products- Food

- No food

Agricultural-

Animals-

Vegetables

Energetic coltivations

Aquatic Land

BIOMASS ENERGY


[3] Source: Corso di Impatto ambientale Modulo b) Aspetti energetici prof. ing. Francesco Asdrubali Energia dalle Biomasse



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


Pirolysis



• 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


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


Powerup to 8 MW [8]

Localization on shore/off shore

TechnologyHorizontal 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]




• Environmental impact

‐ Noise pollution (sound and sub-sound)

‐ Biodiversity

‐ Visual

• Intermittent production

WIND ENERGY


Wind: characteristics



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


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)



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




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


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

Introduction - Theory - Exercises - Business Case - Summary 26



• mature technology

• no local CO2 emissions

• on demand

• storage

• high environmental impact,

• ecosystem damage,

• only electricity production

HYDRAULIC ENERGY


Hydraulic energy: characteristics



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.


• Cogeneration process leads to a more rational use of primary energy with respect to processes that produces separately the two kinds of energy.




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




ChemicalEnergy

mcHi

HeatQ

WorkL

Useful WorkLe

Chemical pollution

Thermalpollution

Mechanical losses

UsefulHeat

Electric energy

Thermalenergy

CHP Vs SHP

ηmηtηc

ChemicalEnergy

mcHi

HeatQ

ηtηc

SH

PC

HP

ChemicalEnergy

mcHi

HeatQ

WorkL

Useful workLe

Chemical pollution

Mechanical losses

Electric and

thermal energy

UsefulHeat

ηmηtηc





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

+ +

8063

85

148

INPUT



OUTPUT



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





The use of cogeneration systems allows

reducing primary energy consumptions

from 15% to 40%, produced electricity

and heat being equals.





• 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.



CHP: characteristics 1/2



• 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.



CHP: characteristics 2/2



Saving can be expressed in mathematical terms as follows [1]:



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



Main components

• Engine

• Generator

• Heat exchanger

• Control system

• Distribution system

• Electric connections

• Electric closet (if the company foresee to sell electric energy)





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]


Source: ENEA Desire – Net Project




Comparison among efficiency of different generators


MCFC


LegendSOFC: 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



Exercises



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




Primary energy saving

SHP


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



HIGH EFFICIENCY ENGINES

Which of the following load profiles is suited for cogeneration?

Chart b

Chart a



HIGH EFFICIENCY ENGINES

Which of the following load profiles is suited for cogeneration?

Chart b

Chart a With use of storage systems



Business Case




Practical example“Hypo Alpe Adria”[7]


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.



Electrical capacity (total) 1,06 MweHeat capacity (total) 1,27 MWthTechnology Motor engineNo. of units 1Manufacturer JenbacherType of fuel Natural gasElectricity (yearly generation) 2,37 GWhHeat (yearly generation) 2,57 GWhYear of costruction 2006Total investment cost € 2.800.000 Financing Own fundsState support Certificates, tax reductionLocation Tavagnacco,Italy



Summary




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




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


http://www.vestas.com/en/products_and_services/turbines/v164-8_0-mw



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


SESEC Training Module 5: Renewable Energy and co-generation

Engineering

Transcript of SESEC Training Module 5: Renewable Energy and co-generation