Upload
rosa-de-maio
View
76
Download
0
Embed Size (px)
Citation preview
Polygeneration and advanced energy
systemsProject on SOFC system for a multi-family
household
Rosa De Maio
Alberto Gaeta
Matteo Pizzicotti
Calogero Andrea Savaia
Household Selection and loads
calculationMULTI-FAMILY HOUSEHOLD
Located in Turin, Italy
4 flats
Each flat has an area of 100 m2
LOADS CALCULATION→ according to the standard “VDI 4655” from Germany
CONSUMPTION LOADS [kWh/day] LOADS [kWh/year]
Electrical Energy 32,9 12000
Heating Energy 120,5 44000
DHW Energy 11,0 4000
Household Selection and loads calculation
Tipical day profiles:
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100
[kW
]
Time [15 min]
Electrical load profile [kW]
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80 90 100
[kW
]
Time [15 min]
Thermal heating load profile [kW]
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100
[kW
]
Time [15 min]
DHW thermal load profile [kW]
Sizing of the SOFC and system layout
designTo find the optimal size, an Aspen Model of the SOFC system has been realized,
and 3 different simulations have been performed.
THERMODYNAMIC VALUE SIM . 1 – 1 kW SIM . 2 – 1,5 kW SIM . 3 – 2 kW
Gross Electrical Power [W] 1000 1500 2000
NG Consumption [kg/s] 3,39E-05 5,09E-05 6,79E-05
Thermal Recovery [W] 469,8 705,5 940,5
Blower 1 (NG) power [W] 1,3 2,0 2,7
Blower 2 (AIR) power [W] 29,7 44,7 59,5
Net Electrical Power[W] 969,0 1453,4 1937,9
Electrical efficiency [%] 0,53 0,53 0,53
Thermal efficiency [%] 0,26 0,26 0,26
Difficulties of SOFC in following instantaneously the requested load
The aim of the system is to auto-produce the internal energy request
SOFC has an estimated life of 14 years
The SOFC sizes have been chosen following these hypothesis:
Thermal energy:
The thermal energy recovered is always too low to cover entirely the energy request, so
it is necessary to integrate the thermal production with a boiler of 12 kW
Economic Analysis
• SOFC COMPONENTS COST
FUEL CELL 10.000 €/kW
SYSTEM FC cost [€]Boiler cost
[€]Additional cost [€] Total investment cost [€]
Fuel Cell (1 kW) + Boiler 10000 1200 392 11592
Fuel Cell (1,5 kW) + Boiler 15000 1200 567 16767
Fuel Cell (2 kW) + Boiler 20000 1200 742 21942
STACK (changed every 5 years) 30% of the SOFC cost
BOILER (η=90%) 100 €/kW
ADDITIONAL COSTS 3,5% of total investment
Economic Analysis
• ELECTRICITY AND NATURAL GAS COST
Base cost
[€/kWh]“Imposta Erariale” [€/kWh]
IVA 10%
[€/kWh]Total electrical energy cost [€/kWh]
0,161336 0,00908 0,017042 0,1874576
ELECTRICITY
Price of electrical energy without taxes
for the reference year 2017
NATURAL GAS
Base cost
[€/Sm3]Duty [€/Sm3] “Addizionale regionale” [€/Sm3]
IVA
[€/Sm3]
Total NG cost
[€/Sm3]
Boiler 0,399913 0,186 0,0258 0,134576 0,746290
FC 0,399913 0,186 0,000134 0,058605 0,644653
The excess of electricity is sold to the grid with a price of 0,039 €/kWh.
Basic price of natural
gas without duties,
published by GSE
Economic Analysis• TOTAL ANNUAL ENERGY COST
Electrical energy
From Grid To Grid
Energy [kWh] Annual cost [€/y] Energy [kWh] Annual revenue [€/y] Total annual cost [€/y]
Fuel Cell [1 kW] + Boiler 3511,7 652,26 0,0 0,00 652,26
Fuel Cell [1,5 kW] + Boiler 1127,5 209,42 1858,9 66,58 142,84
Fuel Cell [2 kW] + Boiler 359,2 66,72 5334,8 191,08 -124,36
Natural gasFuel cell Boiler
Consumption [Sm3] Annual cost [€/y] Consumption [Sm3] Annual cost [€/y]Total annual cost
[€/y]
Fuel Cell [1 kW] + Boiler 1581,6 1019,59 4849,1 3618,82 4638,41
Fuel Cell [1,5 kW] + Boiler 2373,6 1530,12 4620,9 3448,56 4978,67
Fuel Cell [2 kW] + Boiler 3164,4 2039,91 4393,5 3278,85 5318,76
Economic Analysis
• CASH FLOW ANALYSIS
Cumulated cash flow alwaysnegative for SOFC
• initial investment is high;
• every 5 years there is the
necessity to replace the stack;
• overproduced electricity is sold
at a too low price.
It’s useful a comparative analysis between SOFC and boiler-only cases
The annual cost of energy for the boiler-only case is 6187 €
Economic Analysis
The cumulated cash flow of the Fuel Cell is always below that of the boiler
case.
• investment cost for the SOFC is extremely
high;
• operational cost for SOFC is slightly lower
than the boiler-only case;
• every 5 years the difference between the
two cumulated increases;
• selling price is much smaller than the
purchasing one.
• COMPARATIVE ANALYSIS OF SOFC AND BOILER
Economic Analysis
• COMPARATIVE ANALYSIS OF THREE SIZES OF SOFC AND BOILER
Without any subsidies
the gap, with respect to
the boiler-only case,
grows as size of SOFC
increases
The best solution seems to be the boiler-only case
Subsidies• MAKING SOFC COMPETITIVE TECHNOLOGIES
• Subsidies for reduction of operational costs
Earnings from the production of electricity
► In Italy there are not subsidies for fuel cells
As example of subsidy → “Conto Energia” for photovoltaic systems
Chosen “Quinto Conto Energia” (the most recent) :
electricity produced by SOFC for auto-consumption is rewarded with 0,10 €/kWh;
electricity in excess is sent to the grid and gives an equivalent credit of energy.
Subsidies• COMPARATIVE ANALYSIS OF THREE SIZES OF SOFC AND BOILER WITH
SUBSIDY
The cumulated cashflow of the SOFC,after 11-13 years isabove that of theboiler-only caseTime to reach break-even point increaseswith the size of theSOFC, so the moreconvenient solution isthat of 1 kW
Conclusions► Now, the SOFC is a technology in development and still it is not competitive with other
solutions:• The capital costs are still too high and are not compensated by much lower operational costs;
• Need of changing the stack every 5 years;
• Analysis is limited by the fact that:
the total load is considered uniformly split in the entire year with a typical daily profile;
the cost of electricity has been considered constant for all the years of operation of the system.
• can generate a reduction of the investment price and/or a higher income for production;
• can help the diffusion and as a consequence the development of this technology
►In the future, the introduction of subsidies for SOFC:
Thanks for yourattention!