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FuelCell Energy Inc. Message Board

  • sunfundasst sunfundasst Oct 5, 2001 1:20 PM Flag

    Webrand, Avooch or other well informed

    I need information to write a report.

    One section of the report is entitled, "Efficiency in Production of Electricity".

    I would appreciate your assistance in this area.

    I have data about the fuel efficiency of coal fired steam turbines before substractions for transmission, same for single cycle gas turbines, same for double cycle gas turbines. Of course I have data about FCEL with microturbine attached.

    I do not have data for oil fired turbines or
    diesel. I know that transmission is not a sigificant concern for Diesel.

    Please also provide efficiency information about effiency of any other source of combustion utility produced electricity such as the oil produced electricity at Lilco, now Lilco- Keyspan, or Potomac Electric.

    Percent need not be perfect; just need reasonable valid estimates.

    Thanks,

    sunfundasst + sunfund.

    SortNewest  |  Oldest  |  Most Replied Expand all replies
    • Careful with that report. Efficiency numbers seem like a pretty straightforward comparison, but it would take a lot of detective work to make sure you are comparing apples to apples. In fact, if you are looking at the full range of options, from coal and combined cycle down to microturbines and residential FCs, you simply can't compare apples to apples.

      Some of the problems:
      --efficiency ratings often are given for the rated load, but some units are meant for applications where they will rarely run at the rated load
      --some efficiency numbers (especially for smaller systems) may not include a thorough accounting for direct and indirect parasitic losses
      --you can always trade money for efficiency and vice versa, both at the high end (supercritical coal plants with 42% efficiency) and the low end (super-cheap Chinese diesels I've seen advertised for the homesteader types). And everywhere in between, of course
      --local conditions (ranging from climate to water temperature available for cooling) and local emissions regulations can have a substantial impact on practical efficiencies

      I know you aren't trying to put out a peer-reviewed academic paper, but it might be wise to use efficiency ranges rather than single numbers.

      Here's a data point for you:
      Top-quality reciprocating diesel, NG, or dual-fuel diesel/NG engines will give you efficiencies in the 40-42% range (and will do so in the 1-3 MW size range). If the unit is located where NOx control isn't required, you can get even higher efficiency.

      And two more cautions:
      --If you are commenting on transmission and distribution losses don't use webby's 16% number for T&D losses in the U.S. The average is probably 7-8%. No doubt you can find cases (hot day, long distance, heavily loaded route) with 16% losses, but you'll also find 2% cases.
      --Be fair when using projected efficiencies for FCs (such for the FC/turbine hybrids) and note projected gains for other technologies. For example, steam-cooled CCGTs are beginning to enter service with efficiencies in excess of 60%. GRI is working to boost the efficiency of NG engine generators to 45-50%. There also are a number of turbine-based variants (such as Cascaded Humidified Advanced Turbine or chemical recuperation) that can top CC efficiencies or give CC-like efficiencies without requiring a steam turbine.

      One last comment. Efficiency is important, but the popular media and (even more so) the FC investment boards overemphasize its importance. Those sources tend to give one the impression that $/kW and %efficiency are all you need to judge the relative competitiveness of a power-generation technology. That isn't the case, of course.

      Have fun.

      FCa

      • 1 Reply to FC_analyst
      • FC_analyst,

        "<<<Efficiency is important, but the popular media and (even more so) the FC investment boards overemphasize its importance. Those sources tend to give one the impression that $/kW and %efficiency are all you need to judge the relative competitiveness of a power-generation technology. That isn't the case, of course>>>"

        What then, IS the case?

        curious

 
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