NREL Review of 6 "High Performance" Buildings Finds 2 Where Solar Inverters Consume Nightime Power..

...the U.S. Department of Energy’s (DOE) Building Technologies Program has established a goal to create the technology and knowledgebase for marketable zero-energy commercial buildings (ZEBs) by 2025. To help DOE reach its ZEB goal, the Buildings and Thermal Systems Center at the National Renewable Energy Laboratory (NREL) studied six buildings in detail over the past four years to understand the issues related to the design, construction, operation, and evaluation of the current generation of low energy commercial buildings. These buildings and the lessons learned from them help inform a set of best practices—beneficial design elements, technologies, and techniques that should be encouraged in future buildings, as well as pitfalls to be avoided. The lessons learned from these six buildings are also used to guide future research on commercial buildings to meet DOE’s goal for facilitating marketable ZEBs by 2025. The six buildings are...

Measurements in all six buildings showed that they used more energy and produced less energy than predicted in the design/simulation stage. Several reasons were documented:

�� There was often a lack of control software or appropriate control logic to allow the
technologies to work well together.

�� Design teams were too optimistic about the behavior of the occupants and their acceptance of
systems.

�� Energy savings from daylighting were substantial, but were generally less than expected.

�� Plug loads were often greater than design predictions.

�� Effective insulation values are often inflated when comparing the actual building to the as designed building.

�� PV systems experienced a range of operational performance degradations. Common
degradation sources included snow, inverter faults, shading, and parasitic standby losses.

During nighttime hours when the Oberlin or Cambria PV system was in standby mode, the inverters and transformers consumed electricity. The inefficiency of the isolation transformers in these systems results in a power draw of approximately 300 W per 15 kVA transformer. At Oberlin, this standby parasitic load of the three inverters and isolation transformers was a constant 900 to 1000 W during times of no PV production. The primary purpose of the isolation transformers was to transform the three-phase AC 208- delta output of the inverters to utility-compatible, three-phase AC 208-wye/120. The Oberlin no-load transformer inefficiency of 2% of rated capacity resulted in a standby loss of 4,363.5 kWh/yr, or 7.3% of the total PV production. This does not include transformer losses when the PV system is generating power. Cambria’s inverter faults caused considerably greater standby losses. The causes of the inverter faults were a high AC voltage and high temperature. The high temperature fault was the most severe because the system would have to be manually reset. The inverter was removed and sent to the manufacturer in December 2003 and replaced with a new unit in February 2004. From May 31, 2002 to December 31, 2003, the main PV system produced no energy on 50% of the days because of inverter problems. On many other days the system was operational for only part of the day because of inverter problems. From May 31, 2002 to December 31, 2003, the parasitic load on the PV system equaled 40% of the energy delivered to the building by the main PV system. Most of the parasitic load (37%) occurred when the PV system was down at night or because of an inverter fault; the other 3% were transformer losses during PV system operation. From the time the inverter was replaced on February 20, 2004 to December 31, 2004, the main PV system was down only three days because the whole system was shut down. During this same period, the parasitic load of the isolation transformer was 18% of the total energy delivered to the building. The monthly parasitic load varies from 11% in summer to more than 50% in winter

http://www.rsc.org/publishing/journals/EE/article.asp?doi=b809990c

Energy Environ. Sci., 2009, 2, 148 - 173, DOI: 10.1039/b809990c
Review of solutions to global warming, air pollution, and energy security

Mark Z. Jacobson

This paper reviews and ranks major proposed energy-related solutions to global warming, air pollution mortality, and energy security while considering other impacts of the proposed solutions, such as on water supply, land use, wildlife, resource availability, thermal pollution, water chemical pollution, nuclear proliferation, and undernutrition.

Nine electric power sources and two liquid fuel options are considered. The electricity sources include solar-photovoltaics (PV), concentrated solar power (CSP), wind, geothermal, hydroelectric, wave, tidal, nuclear, and coal with carbon capture and storage (CCS) technology. The liquid fuel options include corn-ethanol (E85) and cellulosic-E85. To place the electric and liquid fuel sources on an equal footing, we examine their comparative abilities to address the problems mentioned by powering new-technology vehicles, including battery-electric vehicles (BEVs), hydrogen fuel cell vehicles (HFCVs), and flex-fuel vehicles run on E85.

Twelve combinations of energy source-vehicle type are considered. Upon ranking and weighting each combination with respect to each of 11 impact categories, four clear divisions of ranking, or tiers, emerge.

Tier 1 (highest-ranked) includes wind-BEVs and wind-HFCVs.
Tier 2 includes CSP-BEVs, geothermal-BEVs, PV-BEVs, tidal-BEVs, and wave-BEVs.
Tier 3 includes hydro-BEVs, nuclear-BEVs, and CCS-BEVs.
Tier 4 includes corn- and cellulosic-E85.

Wind-BEVs ranked first in seven out of 11 categories, including the two most important, mortality and climate damage reduction. Although HFCVs are much less efficient than BEVs, wind-HFCVs are still very clean and were ranked second among all combinations.

Tier 2 options provide significant benefits and are recommended.

Tier 3 options are less desirable. However, hydroelectricity, which was ranked ahead of coal-CCS and nuclear with respect to climate and health, is an excellent load balancer, thus recommended.

The Tier 4 combinations (cellulosic- and corn-E85) were ranked lowest overall and with respect to climate, air pollution, land use, wildlife damage, and chemical waste. Cellulosic-E85 ranked lower than corn-E85 overall, primarily due to its potentially larger land footprint based on new data and its higher upstream air pollution emissions than corn-E85.

Whereas cellulosic-E85 may cause the greatest average human mortality, nuclear-BEVs cause the greatest upper-limit mortality risk due to the expansion of plutonium separation and uranium enrichment in nuclear energy facilities worldwide. Wind-BEVs and CSP-BEVs cause the least mortality.

The footprint area of wind-BEVs is 2–6 orders of magnitude less than that of any other option. Because of their low footprint and pollution, wind-BEVs cause the least wildlife loss.

The largest consumer of water is corn-E85. The smallest are wind-, tidal-, and wave-BEVs.

The US could theoretically replace all 2007 onroad vehicles with BEVs powered by 73000–144000 5 MW wind turbines, less than the 300000 airplanes the US produced during World War II, reducing US CO2 by 32.5–32.7% and nearly eliminating 15000/yr vehicle-related air pollution deaths in 2020.

In sum, use of wind, CSP, geothermal, tidal, PV, wave, and hydro to provide electricity for BEVs and HFCVs and, by extension, electricity for the residential, industrial, and commercial sectors, will result in the most benefit among the options considered. The combination of these technologies should be advanced as a solution to global warming, air pollution, and energy security. Coal-CCS and nuclear offer less benefit thus represent an opportunity cost loss, and the biofuel options provide no certain benefit and the greatest negative impacts.

http://www.rsc.org/publishing/journals/EE/article.asp?doi=b809990c

Energy Environ. Sci., 2009, 2, 148 - 173, DOI: 10.1039/b809990c
Review of solutions to global warming, air pollution, and energy security

Mark Z. Jacobson

This paper reviews and ranks major proposed energy-related solutions to global warming, air pollution mortality, and energy security while considering other impacts of the proposed solutions, such as on water supply, land use, wildlife, resource availability, thermal pollution, water chemical pollution, nuclear proliferation, and undernutrition.

Nine electric power sources and two liquid fuel options are considered. The electricity sources include solar-photovoltaics (PV), concentrated solar power (CSP), wind, geothermal, hydroelectric, wave, tidal, nuclear, and coal with carbon capture and storage (CCS) technology. The liquid fuel options include corn-ethanol (E85) and cellulosic-E85. To place the electric and liquid fuel sources on an equal footing, we examine their comparative abilities to address the problems mentioned by powering new-technology vehicles, including battery-electric vehicles (BEVs), hydrogen fuel cell vehicles (HFCVs), and flex-fuel vehicles run on E85.

Twelve combinations of energy source-vehicle type are considered. Upon ranking and weighting each combination with respect to each of 11 impact categories, four clear divisions of ranking, or tiers, emerge.

Tier 1 (highest-ranked) includes wind-BEVs and wind-HFCVs.
Tier 2 includes CSP-BEVs, geothermal-BEVs, PV-BEVs, tidal-BEVs, and wave-BEVs.
Tier 3 includes hydro-BEVs, nuclear-BEVs, and CCS-BEVs.
Tier 4 includes corn- and cellulosic-E85.

Wind-BEVs ranked first in seven out of 11 categories, including the two most important, mortality and climate damage reduction. Although HFCVs are much less efficient than BEVs, wind-HFCVs are still very clean and were ranked second among all combinations.

Tier 2 options provide significant benefits and are recommended.

Tier 3 options are less desirable. However, hydroelectricity, which was ranked ahead of coal-CCS and nuclear with respect to climate and health, is an excellent load balancer, thus recommended.

The Tier 4 combinations (cellulosic- and corn-E85) were ranked lowest overall and with respect to climate, air pollution, land use, wildlife damage, and chemical waste. Cellulosic-E85 ranked lower than corn-E85 overall, primarily due to its potentially larger land footprint based on new data and its higher upstream air pollution emissions than corn-E85.

Whereas cellulosic-E85 may cause the greatest average human mortality, nuclear-BEVs cause the greatest upper-limit mortality risk due to the expansion of plutonium separation and uranium enrichment in nuclear energy facilities worldwide. Wind-BEVs and CSP-BEVs cause the least mortality.

The footprint area of wind-BEVs is 2–6 orders of magnitude less than that of any other option. Because of their low footprint and pollution, wind-BEVs cause the least wildlife loss.

The largest consumer of water is corn-E85. The smallest are wind-, tidal-, and wave-BEVs.

The US could theoretically replace all 2007 onroad vehicles with BEVs powered by 73000–144000 5 MW wind turbines, less than the 300000 airplanes the US produced during World War II, reducing US CO2 by 32.5–32.7% and nearly eliminating 15000/yr vehicle-related air pollution deaths in 2020.

In sum, use of wind, CSP, geothermal, tidal, PV, wave, and hydro to provide electricity for BEVs and HFCVs and, by extension, electricity for the residential, industrial, and commercial sectors, will result in the most benefit among the options considered. The combination of these technologies should be advanced as a solution to global warming, air pollution, and energy security. Coal-CCS and nuclear offer less benefit thus represent an opportunity cost loss, and the biofuel options provide no certain benefit and the greatest negative impacts.