'Under the plan, up to 50 massive wind turbines - described as being 'as tall as Jardine House with blades as long as a Boeing jet' - will be built on the Ninepin islands, or Kwo Chau Kwan To.' SCMP news item February 20 NOT TOO FAST here, not too fast. Let us change the 'will be built' to 'would be built'. This is only a tentative proposal as yet. It has still to be costed, our existing power utilities must have their say and government is still playing coy. But at least we have something more here than the 800kW public relations windmill that Hongkong Electric has so strategically placed on Lamma Island. The proposal by Wind Prospect, a British-based renewable energy company would give us a 200MW wind farm, 250 times as much. Big number, that. But let's put it into perspective. It amounts to only 1.7 per cent of the existing generating capacity Hong Kong has in fossil fuel plants. And this will probably be all that we can get from wind turbine farms. As I understand it, studies by Wind Prospect found that there were really no suitable sites other than the Ninepin one. I also wonder about those 'blades as long as a Boeing jet'. We shall, perhaps, have to make that a small Boeing jet. Typhoon considerations apparently impose strict limitations on the size and engineering of these turbines. As to other renewable energy sources, solar power still costs five times as much as fossil fuel power, geothermal is out as Hong Kong is (thankfully) not in an earthquake zone, hydro power is only available to us through a small pumped storage facility (not really hydro power anyway) and, as to tidal power, Hong Kong is no Bay of Fundy. Let's face it. If we want to go green on energy, our only real option at the moment is to find ways to use less of it. Renewable energy can give us very little extra for the time being. The only thing it can really give us is higher power tariffs. Here is the difficulty. Our utilities price their power on the basis of a formula that allows them a maximum annual return (currently 13.5 per cent) of their net investment in fixed assets. We pay in essence for how much they can generate rather than how much they do generate. The figure will change under the new regulatory formula now under discussion, but the formula will not. And what they can generate is much more than we consume. Aside from the fact that they must have ample spare generating capacity on hand in case of equipment breakdown, Hong Kong just happens to lie in a geographical location where there is an enormous variation in seasonal demand. The bar chart puts this in perspective. On average over the past 10 years we used 71 per cent more power in August than we did in February. During summer our air-conditioners are on, during winter they are off. In Singapore, they are always on, in South Korea they are not much needed. Now let us say that we include wind turbines in the minimum installed generating capacity that we must always have on hand to ensure the power supply is never interrupted. What might happen if there is no wind on a sultry August mid-afternoon? Exactly. And that is why we cannot include wind turbines in our reserve generating capacity. They must always be an extra. But, of course, they are still costly pieces of equipment - more costly per megawatt of capacity than fossil fuel-fired plants, I would guess (and here I tempt a stream of email from greens saying that they are not). What is more, under the proposed new regulatory regime, Hong Kong's utilities would be allowed to earn a higher return on their investment in wind turbines than they would be on fossil fuel plants. What it comes down to is that a wind farm will do a little - emphasis on 'a little' - to limit air pollution from fossil fuel plants. We would always take power from the wind turbines, if available, and this would mean not having to fire up quite as much coal-burning capacity when the wind is blowing. It may mean that we could get 3 per cent of our power from a wind farm although it might constitute only 1.7 per cent of installed capacity. But we could never rely on it and we would have to maintain just as much fossil fuel and nuclear capacity as we would if we had no wind farm at all, which means that the investment in wind farm fixed assets would be surplus investment over and above what we require and thus electricity tariffs would be higher. What we would get is slightly cleaner air. You may think it a worthwhile price to pay, as I do, but let us not fool ourselves. Clean air has a price.