Comparative efficiencies

In this diary, I seem to go on rather a lot about efficiency.  For some the subject may hold little interest, but for me knowing the efficiency at which my Powerspout is operating and trying to improve it, are matters which engage me.

To recap as to what efficiency is in relation to a water turbine, - it's a measure of how good the installation is in translating, into useful electricity, the energy which is available from the fall and flow at a site.  But a consideration of efficiency need not apply only to generators which use hydro power.  It can be applied to generators using any of the energy sources commonly used: coal, gas, nuclear, solar etc.

Recently, in searching for information about how efficient other people's hydro sites are, I have come across the web site of the US Energy Information Administration. It's quite informative. The site can be found at this web link and there is much of interest answering the question: "What is the efficiency of different types of power plant?"

Summarised below is the data the link provides, - the efficiencies are given for the different types of power station in the US, in the year 2016, averaged across the efficiency of all power stations using each form of energy. The point to be noted is that these figures are real figures, derived from actually measuring the efficiency of each and every power plant in the US. It's an exercise done every year and the data presented includes how the figures change year-on-year for the last 10 years. That too is interesting because it shows how efficiencies in each category are tweaked to be better as technology improves over time.

Whilst noting that the efficiency for 'conventional hydroelectric'is 90% (conventional meaning that pumped storage hydro is excluded), it should be made clear that the power plants included in the survey are all large scale installations generating MW's of power, - like the Hoover dam which can put out 1,345,000 kW.  It is the size of such power stations which makes possible efficiency benefits at every stage of the energy transformation process, so that an overall efficiency of 90% becomes possible. The same would never be possible for a Powerspout turbine generating barely 1 kW. Small size is inherently less efficient.

So my 'best' efficiency of 55% comes a long way below the Hoover dam efficiency ! But what I would really like to know is the efficiency seen by other operators of really small sized turbines. How does my 55% compare with them. The web seems to be silent on the matter. Anyone with any reliable info in this area please comment.