emerging technology: dc power in commercial buildings
TRANSCRIPT
Emerging Technology: DC Power in Commercial Buildings December 9, 2014
Presenter: Suzanne Foster Porter, Director, Research and Technical Services, with Ecova
Dave Denkenberger, PhD Ecova
2014 ACEEE Summer Study
Suzanne Foster Porter, Ecova
Catherine Mercier, Ecova
Peter Turnbull, PG&E
Peter May-Ostendorp, PhD Xergy Consulting
Literature Review: Hypothetical Savings Estimates
Authors Year Application Savings Range
LBNL 2011 Data centers 5 – 28%
EPRI 2006 Data centers 20 – 25%
Vossos (MS thesis) 2011 Residential 5 – 35%
LBNL 2011 Residential 30 – 33%
Opportunities in data centers and residential sector analyzed
Lack of analysis of commercial opportunities (namely office space) despite development of EMerge Alliance standards
DC Distribution as an Opportunity?
Migrating to DC Already dominantly DC
Data source: EIA Annual Energy Outlook 2008
50% Office Electricity Use is Lighting & Plug Loads
DC Alternatives Exist...
Appliance Function
Standard Technology
DC Replacement Technology
Lighting Incandescent or fluorescent lamps* Solid-state lighting
Heating Resistive heating element*
Heat pump driven by variable speed drive
Cooling, refrigeration
Induction motor, single-speed compressor
Variable-speed compressor w/brushless DC motor, VFD
Ventilation, pumps Induction motor Brushless DC motor with VFD
Source: Garbesi, Vossos and Shen, 2011. *Indicates standard tech, can run on DC power; replacement not imperative.
Barriers vs. Benefits
Benefits Barriers
Reduction in electronic waste
Easily reconfigurable overhead lighting
Improved power quality
Legacy AC distribution
Lack of DC-ready products
High cost associated with new technology in low volume
Safety
DC wiring losses
System level outages
Analyzing the DC Distribution Opportunity
Electrical Systems Modeling Approach
Capturing energy flows, conversions, distribution and end-uses
Energy Sources Conversion Local Distribution
Load-Level Conversion Loads
AC Grid Power
PV
Met
er
Inverter
Comm Bldg Transformer Wire loss
Wire loss
Wire loss
Wire loss
Power supply
Ballast/ Driver
VFD
Electronics
Lighting
Resistive
DC Motor Equipment
Building Distribution Losses are about 10% of Building Energy Use
DC Distribution Can Reduce ZNE Energy-Use by 8%
Optimize the wiring for cost (shorter runs/lower gauge)
Why DC in ZNE?
Conclusion
ZNE office buildings are a good candidate for DC distribution – Native DC sources (PV) and native DC loads
– Coincidence of PV and loads
– Optimize the wiring for cost (shorter run lengths, bigger gauge)
A single DC distribution system does not save energy in code compliant buildings
– Could consider a parallel dc system for a subset of loads (such as electronics and lighting together)
Significant barriers exist to moving toward DC distribution
Q & A
Thank you!