Learn English – What does “less than unity” mean in the following context…

meaning-in-context

It's about wind power. Here is the context :
"Few topics generate more controversy than capacity credits for wind plant. The capacity credit of any power plant may be defined as a measure of the ability of the plant to contribute to the peak demands of a power system. Capacity credit is often defined as the ratio (firm power capability)/(rated output). As thermal plant is not 100 per cent reliable, values for all plant are less than unity. To a first order, 1,000 MW of nuclear plant corresponds to about 850 MW of firm power and hence has a capacity credit of 0.85; coal plant has a capacity credit of about 0.75. These figures are, roughly, the statistical probability of the plant being available at times of peak demand."

What is meant by this sentence : "values for all plant are less than unity"?
What are these "values"?
I guess the "values" are the results of this "ratio (firm power capability)/(rated output)", aren't they?

Many thanks for your help.

INCIDENTALLY, what is meant by "To a first order"?

Best Answer

"unity" here means the number 1 and the values are the values of the ratio in the preceding sentence. Any sort of efficiency ratio typically has a value of between 0 and 1.

Incidentally, I would expect:

values for all plant are less than unity

to read

values for all plants are less than unity

Related Topic