CASE STUDY: DISTRICT ENERGY SYSTEM
STATE OF NORTH CAROLINA
From Energy & Operational Savings,
to Carbon Reductions, and Lessons Learned
RALEIGH, NC DISTRICT COOLING PROJECT
Customer Challenges:
– Rising energy costs
– Aging infrastructure
– Pressure to reduce energy
consumption and costs
– Limited capital budget for
improvements
– 20 Buildings & 3.5M SF of
cooling load
North Carolina State Government
Complex in Raleigh
DISTRICT COOLING SOLUTION
Project Highlights:
– Expand the chilled water loop
– Installed new high efficiency
centralized chiller plant
– Modernize the existing central plant
– Rehabilitate the existing below
ground TES tank
– Add new TES tank
– Lower supply temp (39 F) and
Improve delta T
NEW CHILLER PLANT TECHNOLOGIES
• Modular chilled water
central plant system
– 2,900 tons
• Thermal Energy
Storage tank
– 2.7 MG
– 3,700 tons
• System Redundancy
TAS MODULAR PLANT INTRODUCTION
• 2,900 ton central
plant system
• Pre-engineered,
modular design
• Factory manufactured
• Compact footprint
Modular design helps mitigate
project, performance and
financial risk
PERFORMANCE TEST REPORT
.704 kW/ton
0.800
0.780
0.760
Plant kW/Ton Field Data
0.740
Plant kW/Ton Prediction
0.720
0.700
0.680
2,000.00
2,200.00
2,400.00
2,600.00
2,800.00
kW/ton
performance
guarantees ensure
that “promised”
savings are
3,000.00
“achieved” savings
PLANT INSTALLATION
• Easy to install
modules
• Minimize site
disruption
• 30% to 40%
savings in schedule
• Ideal for retrofits &
expansion projects
On site 75% less time than
conventional field constructed
chilled water plant
BENEFITS SUMMARY
• Project savings
– Reduced project risk
• Time savings
– Reduced project
schedule
• Financial savings
– Reduced operating
(LLC) costs
TAS Value Proposition
reduced
Time – Risk – Money
NEW CHILLER PLANT TECHNOLOGIES
• Modular chilled water
central plant system
– 2,900 tons
• Thermal Energy
Storage tank
– 2.7 MG
– 3,700 tons
CHILLED WATER TES CONCEPT
CHILLED WATER TES CONCEPT
SHIFTING THE COOLING LOAD
Electric Demand Reduction
Load Profile without TES
Load Profile with TES
…reduces energy consumption &
air emissions at the source.
TES TANK CONSTRUCTION
Efficient Design
Watertight & Maintenance-free
BENEFITS OF THIS TES TANK
– Partially buried – reducing overall height of tank
– Electric demand shifted (3 MW) to off-peak so that
the State of NC can take advantage of rates
– Reduced energy consumption:
• Chillers can run at optimum condition during charging
• Typically charged during the cooler off-peak hours
– Reduced capital costs for additional chiller capacity
– Maintenance-free (no corrosion, no moving parts)
– Aesthetically pleasing
…reduces carbon emissions at the power plant
FINANCIAL AND SYSTEMS BENEFITS
PROJECTED
ACTUAL
Energy Cost Savings
$1.80M
$1.98M
Kwh Reduction, Total
19.8M kWh
21.8M kWh
Kwh Reduction, Lighting Only
2.99M kWh
3.17M kWh
Water Use Reduction
8391 Kgals
8605 Kgals
Fuel Use Reduction
4816 Therms
4752 Therms
Capital Avoidance
$7M
$7M
New Infrastructure
$21.4M
$21.4M
Co2 Reduction
28.1 Kilotons
28.4 Kilotons
- Project was completely developed and financed under State of NC
Energy Performance Contract (EPC)
SAVINGS SUMMARY
–
–
–
–
Reduced kWh consumption (new chilled water plant)
Shifted electric load to night time rates (TES)
Operational and maintenance savings
Expansion of distribution system (increased the savings
impact and improved overall system performance)
Savings are paying for the new
systems and installation with
money left over!
ECONOMIC STIMULUS PLAN
• Economic Stimulus Plan
– $50 billion for energy efficiency
– Institutional market
• Sustainable energy and
infrastructure projects
• Energy efficient innovative
technologies
• Renewable technologies
• CHP applications
– Minimum system efficiency of 60%
• Waste heat recovery applications
CARBON ECONOMIC VALUATION
What will the
market value be
of 19.8M kWh’s
and 3 MW of
electric load
shift?
Do you have
the potential to
reduce kWh
consumption?
FOR MORE INFORMATION
Patrick Sweeney, PE
Phone: (703) 253-1740
Email:
psweeney@pepcoenergy.com
Peter Armstrong
Phone: (832) 615-6247
Email:
parmstrong@tas.com
Guy Frankenfield
Phone: (214) 755-4610
Email:
gfrankenfield@natgun.com
ACKNOWLEDGEMENTS
Owner – North Carolina – State Energy Office
ESCO - Pepco Energy Services
TES Consultant – The Cool Solutions Company
Engineering – Affiliated Engineers, Inc.
Modular Chiller Plant – TAS
Thermal Energy Storage Tank – Natgun
Control Valves – Cool Systems / Flow Control
Controls – Siemens Building Technologies
Utility Company – Progress Energy