14-1101 v2.X Request for Exception: Combustion in a Winery
Based on your team’s suggestion to investigate CO2 heat pumps as an alternative to combustion boilers, we’ve spent the past few weeks working with a representative of the heat pump manufacturer (Mayekawa) and exploring that option. After three weeks of review and research, we believe that we can redesign the planned production hot-water heating system using two CO2 heat pumps and thereby avoid approximately 90% of the combustion load from the original plans. While this system will cost approximately $200,000 more (plus the added cost of additional solar PV panels), we are convinced that it is the superior alternative from an ecological and technological point of view, and that in implementing it we will become even more closely aligned with the Living Building Challenge goals and vision.We had hoped to avoid the use of combustion energy altogether with the CO2 heat pumps, but unfortunately we don’t see that as a viable option. A CO2-only process-water heating system has never been tried in a winery, let alone a winery as large as Silver Oak’s planned facility. During the past weeks’ inquiries it has become clear to us why this technology is not more widely used in the winemaking industry.CO2 heat pumps are quite costly, but in the right circumstances they quickly make up for that cost with their efficient performance. In applications like dairies or breweries, where they function to supply heat for a steady, consistent demand throughout the year, the pumps can be sized appropriately and quickly return the cost of the initial investment. In contrast, the demand at a winery spikes in the fall with harvest for around six weeks. To size the equipment to meet that demand requires an almost comically robust and extraordinarily expensive system that sits mostly dormant for just over ten months of the year.We feel the better approach is to design the system to track load more closely to peak non-harvest demand, as this is the most sensible approach from an engineering, economic and production standpoint.We hope to achieve a compromise with your staff so that we may connect a small, efficient condensing boiler to the non-recycled well water system in the production facility. Doing so provides a much needed measure of security to the owner and winemaking team, and a bit of a safety net for this promising, but somewhat unproven technology.The well water system feeds a few select hose stations in our production area. The propane boiler would only be available during the peak harvest cycle, and even then it would only be used as a failsafe back-up. The boiler will be turned off for approximately 46 weeks out of the year so that during normal operations, only the CO2 heat pumps will be used for hot water.This is necessary so that hot water can quickly be accessed in the event the CO2 system and enlarged tank have been exhausted, which is a serious concern with a CO2-only alternative.The equipment footprint for the planned CO2 heat pump system requires an architectural & engineering redesign to accommodate the larger CO2 heaters, the additional 1,500 gallon of hot water storage, and additional heat exchangers, all of which we are ready and willing to undertake. But we are very hesitant to expand the building footprint to accommodate additional CO2 heat pumps and storage tanks. Our site constraints, from both a vineyard growing perspective and Williamson Act requirements (a CA law dictating a floor under which productive farming acreage cannot fall), give us a finite amount of space for placing buildings and PV panels.Our biggest Energy Petal issue at the moment (aside from this constant pursuit to minimize or eliminate combustion) is that our PV system is maxed out – while we have space for approximately 600kW of rooftop PV, we are scrambling to place close to 200kW of additional PV panels to accomplish the 105% of necessary load required for the energy petal. Additional electrical load will push us beyond our constraints and make achieving the energy requirements in Imperative 06 very difficult, if not impossible.We are oversizing the hot water storage tanks to provide a buffer for anticipated and actual hot water use during the harvest peak use period. In this way we can get the maximum use out of the CO2 heat pumps by drawing from hot water stores in super insulated tanks. The goals for this project include training our teams to be extremely sensitive to resource consumption. Normally, the production crew will be working within the constraints of the CO2 system and so will need to adapt their behavior with water and heat use to work efficiently.If the system-as-designed functions as promised, it should be a rare occurrence that the boiler will need to be fired during the harvest period. Still, the owner team feels that it is a necessary fallback to ensure their high standards for wine production quality. This is consistent with I06-E4 5/2014 which allows for combustion-based solutions for isolated applications.
The Institute agrees that a new exception is warranted. I06-E9 12/2014 Industrial Peak LoadIndustrial applications are allowed to use propane gas water heaters as a short-term peak load backup to the regular domestic and process hot water system. The team must attempt to use bio-methane if it is locally available, and provide a narrative describing
the hot water requirements and alternatives explored in an effort to avoid this Exception, as well as demonstrate
through sub-metering that the gas is only used for the short term processing peak load (i.e. winery "crush" which is approximately 6 weeks long) and not throughout the year.
Post ID 2528