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Combined Heat and Power for Colleges and UniversitiesOriginally broadcast Tuesday, May 22, 2007 | 9:00AM—11:00AM (CT)
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Q & A:Do you have a question? Please use our handy E-Line. Download the Q&A document (PDF). Q&A is also posted below. Answers to the questions posted below are not direct transcriptions from the webinar. Additional information and resources are included. What are the expected annual maintenance costs of each of the prime mover technologies relative to each other? Ken: Generally, our O&M costs for our CHP plant are slightly over $0.005 per kWh. We have a full coverage maintenance contract with Solar Turbines for the three turbines at the west campus. This contract currently costs the university approximately $60,000 per month. It may seem like a large expense, but it is well worth it. We've replaced all turbines at least once under that contract at no cost to the university. John: Ken brings up a very important point that we highly profess at the Midwest CHP Application Center. If you are going to invest in these types of systems, we highly recommend maintenance contracts be purchased along with the prime mover equipment. These costs should always be added into the upfront financial analysis when evaluating your facility. Bill: A little add-in… here at the UIC CHP plant, Ken has relatively low speed reciprocating engines which are why the costs for reciprocating engines are where there are. In general, as the units operate at higher speeds, the O&M costs tend to increase as well. That's why in the above table, maintenance costs can rise above $0.01 per kWh. Also, although not shown in the above table, steam turbines are probably around $0.001 per kWh. What are the expected lifetimes of each of the prime mover technologies relative to each other? Can you address any issues with noise as an obstacle to installing a CHP system? The east campus plant was built adjacent to St. Ignatius High School, a prestigious high school in the city of Chicago. We have not received any noise complaints from the high school. Noise is an issue, particular with the reciprocating engines and not so much with the turbines. Bill: If you are next to a high rise building, there can be noise that exits the stack. If there are very tall buildings that are neighbors, there can be noise issues with those installations. Are the fuel cells relatively quiet compared to the other prime movers? What about the capability of the prime mover to handle large motors starting and stopping? Are turbines more susceptible to upset than reciprocating engines due to their higher speeds? Ken: You have to realize that the grid is behind you, the CHP plant is not taking the total hit of the in-rush current. With a CHP plant, you are in parallel with the grid and there's never been an issue here at the UIC CHP plants in regards to handling large motors. John: We have seen in the smaller CHP systems, in terms of microturbines, at some point have had difficulty in keeping up with large load fluctuations. So I am not saying that as a big negative, but that is where I have seen some concerns. Ken: As in our old plant, we had cross line starters on our chillers that seemed to be much more of problem. But most modern chillers are soft start. Was the load profile studied for the campus and how do you factor that in when designing a CHP system? Several universities have shut down their CHP systems due to the high price of natural gas making it cheaper to purchase grid power than to operate their CHP system. Please comment. John: Another part of the question is the price of natural gas is going up. The price of natural gas is increasing, definitely in Midwest as well in other places; it is getting tougher and tougher to pencil in or do the economic analysis associated with CHP systems because of the volatility of natural gas. You can not get away from that. However, what that tells me is that it really brings home the point of needing to do a good economic analysis, with someone who knows what they are doing, using hour-by-hour simulation, load profiles, and not using average costs. What is the break point between natural gas fuel cost and the grid (electric) cost? What is the spark spread required to make CHP work? Ken: As a side note, looking at today's price of electricity that we are paying here at UIC, it ranges from a low $0.02 per kWh to about $0.09 per kWh during the day. The price of natural gas today is $7.5 per MMBtu. And as an order of magnitude, each turbine is saving the university on the order of $4,400 per day. So today, we are running two turbines so are savings today is a little over $8,000. With the $0.02 to $0.09 per kWh price range, are the turbines at UIC run 24 hours per day or only during peak periods? Bill: The other issue there is if you do cycle the units every day, the maintenance costs tend to go up due to the cycling. I believe they have also determined that if they are losing some money at night at the low cost of electricity, that's not a lot compared to the extra maintenance costs that would occur if they cycled the turbines on and off everyday. What different types of fuels are used in CHP systems? John: If I can add to that, Bill is absolutely correct. Again, I don't have the numbers either, but the preferred fuel or the majority of installed CHP systems are run off of natural gas. What we are seeing here in the Midwest mainly due to price fluctuation and the volatility of natural gas, we are seeing a lot of interest in CHP systems, granted, a little smaller in size, maybe up to a couple Megawatts and down to a half a Megawatt on systems like digester gas, whether it be from waste water treatment plants, animal waste, or food processing waste through anaerobic digesters, and of course we showed an example of landfill gas. The majority of installed CHP systems are run off of natural gas, but we are seeing an interest, in what we call, alternative fuels and the reason is due to the volatility of natural gas. Can a list of Midwest hospitals with CHP technology installed be provided? Also, the Midwest CHP Application Center has developed a series of reports for the hospital market sector in four Midwest states (Illinois, Indiana, Ohio, and Wisconsin) to 1) provide the state energy offices with the necessary market information on the Hospital Sector within their state to plan and organize an appropriate workshop/conference to educate this sector on CHP and its benefits to the Hospital Sector and 2) to provide the state energy offices with many of the technical, financial, communication, and application material that can be utilized in a CHP Hospital education program.
What type of staffing is required to implement a CHP system? Ken: We do a great deal of maintenance ourselves on the reciprocating engines. We do call in the manufacturer for assistance, particularly for supervisory assistance as part of our training program. I can say this, we have the two plants in Chicago, now not only do we operate the CHP plant, we operate the two chiller plants. The east campus chiller plant is about 10,000 tons, and right now the west campus chiller plant is 14,000 tons. We operate the two CHP plants, the two chiller plants, the electrical system, including all of the distribution, the steam distribution, the chilled water distribution, and the high temperature hot water distribution. We have 37 plant operating engineers combined between the two plants along with four supervisors, two at each plant covering two of the three shifts. On the east campus, we have all reciprocating engines. We do nearly all of the plant maintenance ourselves without outside assistance. Bill: When the economics for the west campus were done, we included all of the maintenance for the new CHP equipment as an annual operating cost as part of the financial analysis. Ken: Bill was right, we added no new employees when we built either one of the CHP plants. We used the existing staff that was operating the boilers. John: In our role at the Midwest CHP Application Center, we have talked to many hospitals that have installed CHP and we receive the identical answer from the facility managers at the hospitals that for the most part, they did not have to add anyone to their maintenance staff. Many of the facilities start out using the maintenance contracts, especially on prime movers, such as reciprocating engines, and then find out over a short period of time that their maintenance people are enthralled with the whole system and become very knowledgeable about the system. And so everything that Ken has said that has happened here at UIC with this 50 MW plant, we have heard the same type of feedback at plants that might be in the range of 4-8 MW. Typically, what type of control systems are installed in CHP plants? Are they more industrial or commercial? Are they able to be integrated or are they open technology? Bill: We have installed a number of systems including these. The answer Ken gave is very typical for all of our installations. The gas turbines, reciprocating engines, and steam turbines all come with their own stand alone package which runs the unit. It is very common for them to be uploaded into an industrial grade DCS system that would run the entire facility and all the ancillary equipment that is external to the prime movers. If you do need load management, then you have a third system on top of that as Ken has here with the Brush system. It's all industrial equipment, not commercial. Do you have any tips for negotiating a CHP deal with local utilities? Is it possible to have local utilities capitalize or finance a CHP plant? Ken: John is exactly right. We had to do this twice, when we first built the east campus plant and then when we built the west campus plant. The second CHP plant was much easier, it was a much easier negotiation with the utilty than the first plant. The other aspect here at the university is that we did not go out and try to sell bonds until we were certain that all these issued were addressed, in particular, one we didn't talk about here was getting out EPA permit. We did not decide to build this until we had the approval from the Illinois EPA, which is also very important and a whole sepearte discussion. Bill: If you want to negotiate with the utility, you need to have your Level II feasibility study complete and completed correctly so that you want to know what your economics are. For every one of these systems going in, I have done 2-3 others that did not go in because after negotiations the utility had a new rate structure. You need to do your feasibility study and know what that is. How long did it take to complete the project at UIC? What were the various project stages?
Ken: The CHP project took approximately three years. Another way of showing the project stages are as follows. The Board of Trustees approval was required at various stages of the project. Some of the stages below were completed coincidently.
What maintenance costs were incorporated into the Performa for annual costs? Ken: This cost of $0.005 per kWh was based on the east campus CHP plant that was completed in 1993. Our experience since has proven that the estimated maintenance cost to be a pretty good number. Was the cost of absorption chilling versus electric chilling included in the savings calculation for the west campus CHP plant? Ken: At the west campus, the absorption chillers were previously installed in one of our buildings. At the east side we added a 1,000 ton chiller as part of the expansion of the east campus from 12 MW to 20 MW as a summer thermal load for the plant. What price do you get for wheeling power to the grid? What additional operations and maintenance requirements (scope and magnitude) are typically added to the O&M organization (labor, management, training, certifications, etc.)? Ken: We included training by factory personnel with each of our engine purchases. This training was done on site during a two week period which worked out very well. Our staff performs all maintenance excluding engine overhauls. We have a maintenance contract for our gas turbines, but do routine maintenance with our own people. We added two additional operating engineers for the west campus plant, but no additional engineers at the east campus. We have 18 engineers at the east campus and 19 at the west campus plus a shift supervisor for the day shift and one for the afternoon shift at each plant. There is no supervision on the night shift. These engineers are also responsible for the central chiller plants, steam distribution, chilled water distribution, and electrical distribution system. What is the electric efficiency of larger reciprocating engines (>1 MW) today? Have reciprocating engines exceeded 40%? Ken: The 5.5 MW Wartsila engines are rated right at 40% (8450 btu/kwh). When using an absorption chiller (COP=1) for CHP waste heat is the carbon foot print much different than the electric grid (higher elec efff) with electric chilling (COP=6)? We have seen a trend in small private colleges and institutions taking facilities off the central heating plant as the building is renovated. Can CHP be applied per building or is it better to overhaul the central plant and keep the buildings running off the central system? What specific services do you see the consulting community providing (or needing to provide) to facilitate the increased application of CHP (financial technical regulatory)? Many of our clients are not comfortable with operating or financing a CHP plant. Can you discuss options for third party financing, construction, and operating of a CHP plant? The third party option simply changes who the client buys the electricity from, and they also purchase steam and/or hot water as a utility. This relationship can work, but the third party should have the same business philosophy as the client to satisfy both parties. Remember that every time you get a third party involved, whoever is putting up the money is going to end up with most of the savings. Is IEEE 1547 adopted by IL utilities? How much more efficient is a Desiccant Dehumidification system compared to other forms of humidity removal? The lower the required dew point for space control, the less efficient these conventional processes become as COPs get lower with depressed coil temperatures and cooling capacities get smaller with reheat "false loading". A very general rule of thumb is that as dew point requirements fall into the 45ºF range and lower, desiccant dehumidification should be considered and that application’s competitive operating and first cost economics should be compared between the conventional and desiccant equipment. In the extreme, as dew point requirements fall near or below 32ºF, conventional systems will also have to install and operate defrost mechanisms for the cooling coils. A desiccant dehumidifier avoids this issue since it uses a sorption process to remove water vapor. Also, another very general rule of thumb is that as relative humidity control levels fall to 45% or lower, a conventional mechanical system will end up meeting the cooling load before satisfying the dehumidification load. Again, cooling then reheating approaches will need to be applied by a conventional system to hold that relative humidity control level. Finally, note that the operating economics must take into account the respective cost of electricity for compressor based systems, versus the cost of thermal energy (which could be a waste heat stream from a CHP system) for desiccant based systems. These lower absolute and relative humidity control levels, below typical comfort conditioning levels (55 oF dew points or 55% relative humidity), are very common in many industrial process that require moisture levels to dry products, prevent moisture regain, stop corrosion, etc. An excellent reference on these types of applications is The Dehumidification Handbook available from Munters. Several commercial and institutional buildings can also be candidates for application of desiccant dehumidification. Generally, such buildings fall into one of two general categories. First are the "cold footprint" buildings, such as supermarkets, ice arenas, or cold warehouses, which can achieve more cost effective, combined refrigeration and air conditioning costs with desiccant dehumidification in hybrid arrangements with conventional cooling systems. Second are the "high ventilation air fraction" buildings, such as schools, theaters, and restaurants, which can have such large moisture laden outside air loads in more humid climates that dehumidification can dominate the air conditioning system loads, especially at off-design or part load operation. If not addressed by more effective dehumidification systems, relative humidity levels can climb in these buildings creating occupant discomfort and raising mold concerns. The Humidity Control Design Guide (for Commercial and Institutional Buildings) available from ASHRAE discusses these applications. Finally, a number of emerging "enhanced dehumidification" air conditioning systems are integrating cooling coils and desiccant dehumidifiers into "closely coupled" products which are discussed in a paper available from UIC-ERC. |
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John Cuttica
