The Alaska SeaLife Center uses four 20-ton trans-critical CO2 heat pumps for heating and cooling its 120,000 square foot aquarium facility. Since installing the heat pumps in 2016, they have achieved energy savings of $135,000 and reduced CO2 emissions by 1.3 million pounds. The heat pumps recover heat from seawater and use it to warm various building systems. Additional heat recovery from server rooms and other spaces has improved the system's efficiency since installation. Future plans include more heat recovery to further reduce energy costs and increase the heat pumps' coefficient of performance.

2. Enhancing Performance of Trans-critical CO2
Heat Pumps with Heat Recovery in Alaska
Darryl Schaefermeyer
Special Projects Director,
Emeritus
Alaska SeaLife Center
Andy Baker, PE
Project Manager,
CO2 Heat Pump System Designer
YourCleanEnergy LLC

3. Alaska SeaLife Center - 120,000 Ft2 Aquarium
Sub – arctic climate
Opened in 1998, the Alaska SeaLife Center
occupies a unique niche in cold water marine
research: it combines research, rehabilitation and
education under one roof. It’s the only public
aquarium in Alaska. By generating and sharing
scientific knowledge promoting an understanding
and stewardship of Alaska’s marine ecosystems,
it serves as the main public source of information
on Alaska marine research.
Since opening, the Center has received over
3,000,000 visitors. To date, its research staff has
authored close to 300 journal publications and
delivered over 700 scientific presentations at
conferences.
Averaging a COP of two for the period 2016-2018,
the Center’s four Mayekawa 20-ton seawater
source heat pumps have achieved net energy
savings of $135,000 while avoiding 1.3 million
pounds of CO2.
The ASLC is an accredited member of the
Association of Zoos and Aquariums.www.alaskasealife.org

4. Four x 20 ton Trans-critical CO2 Mayekawa Heat Pumps Installed At
Alaska SeaLife Center In January 2016 – Emerging Energy Tech Grant
• CO2 heat pumps piped in parallel
to offset 500 KW electric boiler,
cascading heat loads required.
• Load side heat supplements main
hydronic bldg loop at 160F; then
domestic hot water tank @145F;
then heating coil @130F; then
outdoor slab heat @120F; return
to CO2 heat pumps @100-120F.
• Seawater (38F-54F) is primary
source heat; fan coils in electrical
and mechanical rooms warm
source glycol by 5F - reduces sea
water pumping, increases COP.

5. RTWD HP Heat
Energy
52%
CO2 HPs Heat
Energy*
34%
CO2 HPs Cooling
Energy
2%
Electric Boiler
Heat Energy
11%
DHW Immersion
Heater Energy
1%
Heating & Cooling Energy Production
ASLC Heat Pump System - CY2018
•In 2018 – 88% of heating and
cooling done by heat pump
systems; 36% by CO2 HP’s
•Largest opportunity to
improve performance of CO2
heat pump system is to
increase heat recovery into
cold source glycol entering
heat pumps
•More fan coils to be added!!!

6. Heat Recovery From Fan Coils In Electrical & Mechanical Rooms Has
Improved Trans-critical CO2 Heat Pump System Since January 2016

7. Source Side Heat Recovery To Be Enhanced In 2019 With New
Fan Coils In Over-heating IT Server Room & Tissue Freezer Room
• All heat recovery
loads will be moved
to the source leaving
side of heat pumps,
fan coils get colder
glycol and perform
better.
• Additional elements
of heat recovery will
reduce required
seawater pumping,
reduce operation
cost, and increase
system COP.

8. • Heat Recovery
from mechanical
room, electrical
room, refrigeration
room, IT server room
using fan coils =
improved COP !!!
• Using leftover load
side heat to pre-heat
source also =
improved COP !!!

9. Lesson In Heat Recovery Learned From Alaska SeaLife Center
- Will Be Applied To District Heat Project - Four City Buildings

10. Design Includes Heat Recovery From Library Mechanical Rooms
- Fan Coils Will Warm Source Side Glycol Temp & Increase COP