Evaluating Costs and Benefits of a Smart

Polygeneration Microgrid Project in a University Campus

Stefano Bracco*, Federico Delfino**, Fabio Pampararo**, Michela Robba*** and Mansueto Rossi**

University of Genoa - ITALY

*Dept. of Mechanical, Energy, Management & Transportation Engineering

**Dept. of Electrical, Naval & ICT Engineering

***Dept. of Informatics, Bioengineering, Robotics & Systems Engineering

federico.delfino@unige.it

Outline of the presentation

• The Savona Campus: a research & teaching facility of the

University of Genoa

• The Smart Polygeneration Microgrid (SPM) project

• The Smart Energy Building (SEB) project

• Economic & Environmental Analysis

o Reduction of annual energy operating costs

o Reduction of CO2 emissions

• Conclusions

The Savona Campus: a R&T facility of the University of Genoa

• 50,000 square meters• courses from the Faculties

of Engineering, Medicine, and Media Sciences

• laboratories, research centers and private companies (several operating in the environment &energy field)

• library, residences, canteen, café, etc…

The Smart Polygeneration Microgrid (SPM) Project

• Special project in the energy sector funded by the Italian Ministry of Education,

University and Research (amount 2.4 M€)

• SPM is a 3-phase low voltage (400 V line-to-line) “intelligent” distribution system

running inside Savona Campus and connecting:

• 2 mCHP Gas Turbine (95kWe, 170 kWth) fed by natural gas;

• 1 PV field (80 kWp);

• 3 CSP equipped with Stirling engines (3 kWe; 9 kWth);

• 1 absorption chiller (H2O/LiBr) with a storage tank;

• 1 electrical storage: NaNiCl2 batteries (100 kWh)

• 2 PEV charging stations.

The Smart Polygeneration Microgrid (SPM) Project

SPM one-line diagram:- 400 V distribution system (ring network, 500m long)-five switchboards

The Smart Polygeneration Microgrid (SPM) Project

SPM planning, supervision & control system

RTUTM 1703 ACP

planning & management

supervision& control

field data acquisitions &local automation

IEC 61850

SICAM

DEMS

The Smart Polygeneration Microgrid (SPM) Project

SPM ICT infrastructure

The Smart Polygeneration Microgrid (SPM) Project

Main goals:• to build a R&D facility test-bed for both renewable and fossil

energy sources • to promote joint scientific programs among University, industrial

companies and distribution network operators Day-ahead production scheduling of dispatchable

sources and storage exploiting renewables forecast and optimization techniques

• to optimize thermal & electrical energy consumptions, minimizing the CO2 emissions, annual operating costs and primary energy use of the whole University Campus

The Smart Energy Building (SEB) Project

• Special project in the energy efficiency sector funded by the Italian Ministry for

Environment (amount 3.0 M€)

• SEB is an environmentally sustainable building connected to the SPM, equipped by

renewable power plants and characterized by energy efficiency measures:

• Geothermal heat pump

• PV plant on the roof (20 kWp)

• Micro wind turbine (horizontal axis, 3 kW)

• High performance thermal insulation

materials for building applications

• Ventilated facades

SPM & SEB inside the Savona Campus of the University of Genoa

• SEB is an “active load” of the SPM

SEB is an energy “PROSUMER”

Storage-related research activity

• SPM OPTIMAL SCHEDULING DEMS uses

o costs and revenues functions;o forecast of electric and thermal energy demand;o operative constraints (equipment ratings, maximum power ramp, etc.);o forecast of the renewable units production by resorting to weather services and

historical records

to compute a scheduling for dispatchable sources including storage, which minimizes the daily energy costs. The optimization process has a time-horizon of 1 day (typical of a day-ahead energy market session), subdivided in 15 minutes time-intervals. The optimization method is based on linear programming.

• This research line results at the storage level in an automatic production shifting application

Storage-related research activity

Storage state of charge variation on a typical winter day

Production from dispatchable sources PV Production & Demands

Economic & Environmental Analysis

• Two different scenarios are considered

AS-ISWithout SPM & SEB

TO-BEWith SPM & SEB

• Electrical Energy → National Grid + SPM + SEB• Thermal Energy → 2 boilers + SPM + SEB

• Electrical Energy → National Grid• Thermal Energy → 2 boilers (gas,1000 kWth)

AS-IS scenario: energy consumptions and operating costs

Including also maintenance

cost

TO BE scenario: share of electricity and heat generation

ELECTRICITY˜ 37% delivered by

SPM and SEB generation units

HEAT˜ 25% delivered by

SPM and SEB generation units

SPM / SEB energy consumption and production

Assumptions:

- winter operation for mGTs,2000 hours at rated power

- absorption chiller turned off

Calculation of the total operating costs for the 2 scenarios

_ _T AS IS AS IS pp AS IS pp m AS ISC EEC e TEC TES C

_ _ _ _

_ _ _ _65, 30

T TO BE el Grid pp th Boiler pp m TO BE

el SPM el SEB f f k f kk C C

C E e E TES C

E E e M p

where:

_ _ _ _ _el Grid AS IS el EHP el SPM el SEB el SEBE EEC E E E E

_ _ _th Boiler AS IS th SPM th SEBE TEC E E

and Cm and pf being respectively the maintenance cost and the natural gas price for the mGTs

; Mf_k = m3 natural gas used by

each mGT

Calculation of the total operating costs for the 2 scenarios

where:  ef-n = 0.465 tCO2/MWhel (the emission factor of the Italian electrical mix); ηel_Grid =0.9 (national electrical grid efficiency);

ef-NG = 1.961·10-3 tCO2/m3 (natural gas emission factor);

Of = 0.995 (natural gas oxidation factor);

LHV=9.7·10-3 MWhpe/m3 (natural gas lower heating value).

Calculation of the CO2 emissions for the 2 scenarios

2__

f n f NG fAS IS AS IS AS IS

el Grid Boiler

e e OCO EEC TEC

LHV

_2 _ _ _

65, 30_

+f n th BolilerTO BE el Grid f NG f f k

k C Cel Grid Boiler

e ECO E e O M

LHV

Calculation of the CO2 emissions for the 2 scenarios

Economic & Environmental Analysis

Economic and environmental benefits provided by the system SPM + SEB can be further increased by:

• using the mGTs in trigeneration asset (resorting to the absorption chiller) in order to cool the library of the Savona Campus (now cooled by means of an electrical heat pump) during summer months (+ 600 working hours for the mGTs with respect to the examined case)

Conclusions

• The “Sustainable Energy” R&D infrastructures under construction at the Savona Campus of the University of Genoa have been described and the main research lines that can be investigated by means of their use have been outlined

• An approach has been presented to assess the Campus operating costs, CO2 emissions and primary energy saving on a yearly time-scale

• It has been shown that the Smart Polygneration Microgrid (SPM) and the Smart Energy Building (SEB) contribute to increase the overall energy efficiency of the Campus, lowering its environmental impact

• It should be underlined that the revenues obtained by the improved energy performances of the whole Campus can be then employed to financially support research activities and to yearly upgrade the two pilot plants SPM + SEB

Thank you for the attention

Federico DelfinoUniversity of Genoa – ITALY

Dept. of Electrical, Naval & ICT Engineering

federico.delfino@unige.it

Vale!