OK, they posed the question and, given the monopoly thing, it's a very important question. Intuitively the answer of course is - well, your being a monopoly and all, we confidently expect you are inefficient - it's just a question of scale. As it happens, a lot of the old CEGB inefficiency (which was grotesque, BTW) was kicked out of the system in the decade or so following privatisation. But it's been creeping back, courtesy of the renewables upsurge. The aforesaid authorities rely totally upon the Grid to facilitate their manic policies, and don't feel inclined to question them particularly closely on how they go about it.** ++
Anyhow: having posed the fateful question, the Grid declines to answer it, relying on the usual PR sleight of hand. Are we efficient? Well, it's all very difficult as we hope you understand.
And - boy, oh boy - are we effective!! 99.9999% reliable!! Six nines!! Go Grid !!
This raises some interesting issues.
- Effectiveness has minimal bearing on efficiency, even if the first 3 letters are the same. I assume, however, that loads of suckers are focus-group proven not to notice the difference.
- The whole matter is one of Gold Plating - the old CEGB disease. We know you can be staggeringly effective if you throw money at it. Our money.
- WTF does six nines mean in this context anyway? One hour's unreliability in 120 years? The Grid hasn't been around that long. One second in 12 days? (Incidentally, 'grid reliability' isn't what most people would associate with continuity in supply of their electricity. Blackouts happen all the time, of course: but almost all of them occur at the distribution level - storm damage, pneumatic drill through cable etc - for which National Grid is not responsible. 'Grid reliability' is more to do with 'quality of electricity'.)
- Most weightily: what is the optimum degree of reliability? Thoughtful people realise that the cost of going from, say, five nines to six nines is many times greater than going from four to five. Who needs six? There may be an answer to that question: it will probably be the manufacturers of ultra-high-tech electrical components. But they typically modulate their power supplies themselves, so as to be even more sure.
Not something we can solve on a Sunday morning. One more observation on the Grid, though. Just a very few years ago they told us we needed a capacity margin (i.e. excess of power generating capacity over peak demand) of 20%. Funnily enough, now that it's negative, they tell us that we only need 6% (and they procure the top-up in various costly ways).
Yeah, funny that. Efficient? Effective? Eff .... Lay off the bullshit PR, eh, boys?
** although one-time Energy Secretary Amber Rudd - remember her? - announced this was going to change ... We can but hope.
++ UPDATE: now here's a thing, from today's DTel.
National Grid’s ‘unnecessary’ power reserve cost £180m - and wasn’t used. In the winter of 2014/15 National Grid paid £23.5m to form a reserve bench of 10 power plants which could be used if cold, dark weather caused demand for power to surge higher than the UK’s power market could meet. The payment later spiralled because the rate per unit of generation capacity doubled, the report found. In the first winter of the scheme the rate averaged £15.57 per kW but by the third winter of the scheme National Grid was paying £34.21 per kW.(Of course, the Grid makes the obvious point about insurance payments ...)