Monday, November 5, 2012

Clean Air, Saved Energy

The US Energy Information Administration (EIA) has released its Annual Energy Review 2011. According to the 300+ page Review’s Preface,

"[t]his thirtieth edition of the Annual Energy Review (AER) presents the U.S. Energy Information Administration’s (EIA) most comprehensive look at integrated energy statistics. The summary statistics on the Nation’s energy production, consumption, trade, stocks, and prices cover all major energy commodities and all energy-consuming sectors of the U.S. economy from 1949 through 2011. The AER is EIA’s historical record of energy statistics and, because the coverage spans six decades, the statistics in this report are well-suited to long-term trend analysis."
The 2011 AER summarizes electricity use in commercial buildings. For the latest full reporting year for that data (2003), heating, ventilation and cooling (HVAC) consumed 1.08 quadrillion Btu, out of a total 3.56 quadrillion Btu for all commercial buildings, or 30%  (AER Table 2.11). By comparison, and interpolating AER’s 2001 and 2005 data, household electrical energy consumption in 2003 for space heating and air conditioning was 1.07 quadrillion Btu, out of a total estimated household electrical energy consumption that year of 4.07 quadrillion Btu (26%) (AER Table 2.5). Thus, for both commercial and residential buildings about 28 percent of the electricity consumed goes toward HVAC. Residential electricity use in 2003 totaled about 14 percent more than all commercial use.
Energy use for HVAC is significant, and technology that can provide more efficient HVAC could lead to fuel savings and emissions reductions.

Enter patent US 8,157,892, granted under the USPTO Green Tech Pilot Program and issued in April 2012 (an 11 month pendency – May 17, 2011 filing to April 17, 2012 issue. USPTO’s goal of accelerated examination certainly was achieved with this patent). Awarded to inventor Udi Meirav (Newton, MA) and assigned to Enverid Systems, Inc. (also in Newton), “Method and system for improved-efficiency air-conditioning” is found in Way Better Patents Air Index. An air patent that reduces energy use – how can that be?
We wrote recently about “teaching” in patents. This one provides good teaching about HVAC. Mr. Meirav writes,
"Central HVAC systems in buildings typically include one or more central air handling unit(s) and an air distribution system, where supply air is directed to various parts of a building through a network of ducts, and return air flows from these spaces, through other ducts or a plenum, back to the air handling unit(s). In the air handling unit, the air is cooled and/or heated, as well as filtered and often dehumidified and/or humidified, as needed. Thus, HVAC systems constantly circulate air through the building while continually adjusting its temperature and humidity to maintain comfortable environment. 
"However, in order to maintain good air quality, not all the air is recirculated. Some of the air leaks out through doors, windows, etc. and some fraction of the circulating air is intentionally exhausted outside the building. This is referred to as exhaust air. The exhaust air is replaced by an intake of outside air, also known as makeup air, to make up for the exhaust air being taken out. This is also referred to as “fresh air” or ventilation. This replacement of air is done because occupants of the building and the equipment consume oxygen and emit carbon dioxide (CO2) as well as a variety of other contaminants that gradually compromise quality and safety of the air. Such replacement of the air maintains fresh air quality. 
"Oxygen represents approximately 21% of atmospheric air and that is normally the desired level of indoor air as well. On the other hand CO2 is present only in very low levels in the outside air, typically at a level of approximately 400 parts per million (“ppm”). Once elevated levels of CO2 or reduced levels of oxygen are created, a fairly significant amount of outside air is needed to bring their respective concentrations close to the desired level. Indeed, to fully restore oxygen and CO2 concentration virtually all the air may need to be replaced. 
"The outside air represents an additional, and depending on the outside climate conditions often a significant, thermal load on the air handling unit. In the case of a hot and humid climate, for example, the outside air injected into the HVAC system can require additional energy for cooling and dehumidifying the outside air and can represent a significant fraction of the entire thermal load and energy usage of the HVAC system."
Claim 1 states the central concept of the invention:
A system for circulating air in an enclosed environment, comprising:
an inlet configured to receive air from outside of the enclosed environment; 
an air handling unit coupled to the inlet to receive the outside air through the inlet and configured to receive a circulated air from the enclosed environment; 
the air handling unit is configured to affect a temperature of at least one of the received outside air and the received circulated air; 
based on the received outside air and the received circulated air, the air handling unit is further configured to generate air for supplying to the enclosed environment; 
an air circulation system configured to circulate the generated air from the air handling unit to the enclosed environment and back to the air handling unit; 
a scrubbing system coupled to at least one of the air handling unit and the air circulation system and configured to reduce presence of at least one substance in the air supplied to the enclosed environment, wherein the scrubbing system includes at least one adsorbent, and wherein a concentration of the at least one substance is reduced by adsorption of the at least one substance onto the adsorbent.
The patent’s representative drawing,
"illustrat[es] a circulating central HVAC system 100. The system 100 can be configured to provide air circulation to an occupied space 102 to which it is connected. The system 100 further includes an air handling unit (“AHU”) 106, which has both heating and cooling elements that modify temperature of the circulating air as it flows and comes in contact with these elements. The system 100 can further include air intake duct(s) 108 connected to the AHU 106 via circulation lines 104 that allow intake of outside air (“OA”) into the system 100 and specifically AHU 106. The system 100 can also include exhaust duct(s) 112 that receive return air (“RA”) via lines 110 and expunge it as an exhaust air (“EA”) into the outside atmosphere (or any other environment). 
In operation, the fans or blowers that can be disposed in the AHU 106 force the flow of the conditioned supply air (“SA”) through ducts that distribute the conditioned air throughout the various parts of the occupied space 102 (which can be an enclosed environment). For ease of illustration, the following description refers to a building as an example of an enclosed environment 102. The building 102 can have different zones for which rates of air flow can be different. Return air can flow back to the air handling unit 106 via lines 114 and can be filtered to remove particles, bacteria, substances, various fumes, and/or a combination thereof. Some of the return air can be exhausted outside the building 102 as exhaust air. The air can be exhausted through valves that control the amount of exhaust air being released. At the same time, fresh outside air can be pulled in to replace the exhaust air and maintain a correct overall volume and pressure of air in the building 102. Typically 10–15% of airflow can be released as exhaust and replaced, but this number can vary widely. In some environments, such as bathrooms and kitchens, the HVAC system can be configured to exhaust and replace 100% of the air flow. The constant replacement of exhaust air with outside air can be intended to maintain good air quality, and in particular, replenish oxygen consumed by the building occupants and remove substances, particles, gases (e.g., carbon dioxide), fumes other compounds, and/or a combination thereof generated by occupants, equipment and/or materials located inside the enclosed environment 102. 
In some embodiments, the enclosed environment 102 can be an office building, a commercial building, a bank, a residential building, a house, a school, a factory, a hospital, a store, a mall, an indoor entertainment venue, a storage facility, a laboratory, a vehicle, an aircraft, a ship, a bus, a theatre, a partially and/or fully enclosed arena, an education facility, a library and/or other partially and/or fully enclosed structure and/or facility which can be at times occupied by equipment, materials, live occupants (e.g., humans, animals, synthetic organisms, etc.), etc., and/or any combination thereof.
Did you catch that last paragraph? The inventor envisions that his CO2 scrubbing system can be applied to any partially or fully enclosed structure occupied by anything.