Finally some rain again in Sydney, it has been pretty dry. It is not much better in some parts of country NSW, as this article in the SMH attests to. In contrast, Victoria seems to be getting plenty for a change. The climate keeps us guessing where the falls will occur this time.
While I was mulling over this variability this morning, I listened to Macca on the ABC. I always get a bit upset with him, but maybe that is ok. I think he tends to be very simplistic in some of his environment comments, or maybe it is just that he lets people I don’t agree with air on the show. So that is not a bad thing, I can write my blog, he can have these people on the show. Anyway, this morning someone was having a go at wind energy and arguing that we would still need coal fired plants to pick up the peak demand. The main concern of the caller was the visual damage of wind energy to the landscape.
It is totally correct that wind, solar, wave etc energy has difficulties to deal with peak demand. In fact the only non fossil fuel driven energy generation that currently can deal with peak demands is hydro. Let me also be clear that there is no doubt that all types of energy generation, be it fossil fuel or non-fossil fuel have major impacts on the local landscape. All require large installations, some dig up the earth, some make lots of noise, etc. There is no escape, as always, we humans will impact our environment whatever we do. The advantages of non-fossil fuels are that it is renewable and that it has no CO2 output.
There is another regular caller to Macca’s program (however not during today’s program) who I think put the finger on the spot: Dick Smith has argued that the problem with solar was all a problem with storage! Nobody has yet figured out to make efficient and convenient batteries. I think he is right. I think we do have a storage problem, not only in energy, but also in water.
All water our storage is highly inefficient. Evaporation rates from open water are extremely high in Australia. I just plucked these statistics for Lake Burragorang (behind Warragamba Dam and the main water supply for Sydney) of the Sydney Catchment Authority website:
• Capacity: 2,031,000 megalitres
• Area: 75 square kilometres
Average Daily summer evaporation from open water in the summer at Sydney airport (closest station) are between 6.5 – 7.5 mm/day. If Lake Burragorang is totally full (75 km2) than it loses 75*1000*1000*0.007 = 525,000 m3 per day this is (wait for it...) 525 ML/day. I know this is only 0.02% of the storage capacity, but it is still 525 olympic swimming pools per day to use the popular translation. In a week, this means it loses 0.14% just from evaporation. At the moment, the lake is about 54% full and lost 8,020 ML this week of which approximately (54%*525*7 =) 1984 ML or about 20 - 25% is due to evaporation. That is of course very roughly calculated, but it indicates the magnitude of such losses.
This gets me back to the storage problem. Clearly we have a problem with storing water. If we can work out a more efficient way of storing water we would be able to save 20 – 25% of our water. But what are the options. For urban water, we can recover the 20 – 25% simply by recycling, but other options are possible. For agriculture, the issue is more interesting. One of the often raised options is using groundwater aquifers to store water. This involves pumping water into the ground in times of plenty and pumping it out in times of scarcity and for example rainwater harvesting also falls under this heading. This plan has its merits but does need some careful consideration. One of the major issues is one of water quality: In Australia much of the groundwater is often lower in quality (saline) so picking your spot could be difficult. In addition it is a bit like catching fish, labelling it as yours and throwing it back: There is no guarantee you might get the same amount of water back as you put in, so planning becomes a bit of challenge.
For agriculture, just storing more soil water is still another option to maybe be able to use irrigation less. How this would be done, I currently don’t know, but I think it worth working on. Somebody contacted me earlier on this blog that he had a solution in this area, so I think it might be a case of “watch this space”. As this person had commercial interests, I referred him to the South Australian Water Industry Alliance who provide an excellent forum for such interests.
Storage of water in both natural systems has also many more interesting aspects. In particular, I think we need to understand more about the behaviour of soil water storage in varying climate. Something I plan to work on pretty soon (As soon as I can get these other papers finished!).