I Have The Power!

at 6/5/2007 1:36:58 PM, ipdrive said:
Nobody will disagree with you that microturbine effiency is at best 28% and a grid supplied power is about 31%. What you failed to mention is that grid supplied electricity has on average a 7% loss due to distribution losses. That puts average grid efficiency at 24%. Even with that said, 24% vs 28% ( or 28% vs 31% if you don't account for the 7% l oss ) still isn't enough reason to sell the microturbine case. You failed to mention that the majority of microturbine DE installations are a) CHP/CCHP related that yield around 80% effiency b) Used to capture energy from gas that would either be vented or flaired into the atmosphere. Thus yielding 28% or greater effiency with what is essentially free fuel. In these instances - which is a niche market, but IS THE market for microturbines - your statement of "hat its better for the environment and the pocket book to pull electrons from the grid then generate them on-site with a microturbine." is 100% wrong.

at 6/8/2007 1:03:56 PM, Confused said:
Everone are talking about "Neo aerodyncamic" Can someone give me some feedbacks?

at 7/2/2007 10:59:44 PM, Felipe said:
Your comments regarding MicroTurbine effiency are warranted. The Capstone 30kW and 60 kW MicroTurbines are about 28% efficient under the best of circumstances. This efficiency is based on sea-level standard day conditions, which is 59 degF. On hot day conditions where the grid is taxed, the efficiency falls off considerably. This is a function of the maximum turbine exit temperature, which must be held as a constant regardless of ambient temperature. At altitude, where the air is less dense, the turbine efficiency is also degraded. Next, take into account the natural gas supply. Most facility gas supply pressures are about 5 psia and the gas pressure must exceed the combustion inlet pressure, which is similar to the compressor exit temperature. The electrical loses for running a gas compressor are significant. Also, load following may require running the gas turbine at less then maximum power. Part power operation is significantly less efficient then maximum power operation. Thus, a 28% microturbine may only be 18% efficient under these circumstances (ambient temperature, pressure, gas pressure, and load). Next, let's consider co-generation. The 90% efficiency is only achieved under perfect circumstances where 100% of the heat load and 100% of the power load is used, which is rare. This is referred to as "heat balance." In most cases, a portion of the heat or power is used, dropping the efficiency significantly. This 90% efficiency is also quoted at sea-level standard day conditions. Considering a standard natural gas water heater is 80% efficient, it is comparable with the expected efficiency of a co-generation microturbine application where the heat and power load are not perfect. Thus, a low cost natural gas hot water heater is as or more efficient then a microturbine co-generation system at a fraction of the cost. Agreed, free fuel is the best application for a microturbine, but this a tiny niche market and the free "dirty" fuel must be cleaned by scrubbers, which is costly and difficult to maintain. Thus, it may be cheaper to simply flare the gas. It is true that if MicroTurbines were more efficient then the grid or recips, they would be everywhere.

at 7/9/2007 9:11:26 AM, dave said:
The 31.5% grid efficiency is after the 7% distribution losses according to the DOE site.

at 2/22/2008 5:43:17 PM, Bill said:
There is some literature on the use of microturbines in hybrid bus applications. The suggestion is that they burn approx. 50% less fuel than the diesel alternative. Would you care to comment on this niche market? R/ Bill

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