Wading recklessly into the water ownership debate

By Marcus Wilson 16/08/2012 5

If you’re in New Zealand, you cannot have failed to be aware of the legal wranglings over the ownership of water. Who owns or has rights to the water in our rivers? The raising of this question is a not-so-subtle attempt from one half of the political spectrum to delay (or stop) the sale of state-owned-enterprises (notably hydroelectricity companies) by the other half of the political spectrum. Basically, if the water isn’t the government’s, then it can’t sell it, so it isn’t able to privatise the hydro companies – at least that’s the argument in hopelessly over-simplified terms.

There’s one issue regarding this that I haven’t heard at all in all the debate that is happening. What is it that the government is actually trying to sell?  It isn’t the water.  Hydro power does not involve the removal of water from the rivers. What flows into the station flows out again. So it isn’t water that is the asset that is being sold here. Rather, it’s electrical energy that the hydro-company sells. The energy is gravitational potential energy, as a result of gravity – a litre of water at a height is able to give up energy as it falls – e.g. into kinetic or movement energy. This kinetic energy is then transferred by the turbines in the power station into electrical energy. The water doesn’t vanish in the process; it simply loses height, and with it energy.

It’s similar to the way that electrical current isn’t ‘used up’ by a heater, light bulb or other device. You have two wires (discounting any earth wire) connected to the device. Current flows in one, and the same current flows out of the other. (Indeed, in a domestic supply, it reverses its direction 50 times a second.) How come then you get an electricity bill if what flows in flows out again? It’s because you are being billed for the energy that is transferred through this process. Putting that current through the device leads to transfer of energy from the power grid to the device, just like turning on the water flow through a turbine leads to energy being taken from the water.

So the question shouldn’t be over who owns the water. It should be over who has the right to do something useful with that water. 





5 Responses to “Wading recklessly into the water ownership debate”

  • Which is why most discussions about this issue talk about “water rights” and not about “water ownership”.

  • Yes, this issue is more one of water rights – access to and use of water rather than something a kin to property ownership of the water. More specifically, one could think of it as an issue of kaitiakitanga or guardianship. This is awfully tricky though, and science is not going to solve this type of issue.

    The analogy of water flow to electrical current is a good one. But I’ll up the ante a bit. While the current and water quantity aren’t used up, the timing of the current and water flow are changed. Dams, while not used by all hydropower stations, are much like capacitors, used to store energy and increase hydraulic head. In fact, reservoir capacitors are specifically used to smooth electrical output. This has all sorts of implications for other aspects of the aquatic system, such as the mobilisation and transport of sediment and rocks downstream, which are more responsive to flow variability than to the mean flow. Another issue is that dams inhibit the migration of fish. But these are complications that electrical circuits do not need to consider, even with electric eels. [Daniel]

  • What I keep asking myself is what is the difference between water and air in this context?
    Both are dynamic and are used for what they do, and are not used up. Both are necessary for life, both can be contaminated.
    With all the debate over water rights, how far away are we from debating air rights?

  • Where science does have an important role to play is in advising on how water can be best utilised and how clean water can be provided to the whole populations.
    I think one of the most important future technologies will be in the area of water purification. This is an area which will be quite lucrative in the future

  • Yes, the air issue. Who has air rights? Will we be billed in the future for our use of air? Will we all have to go around with airflow meters attached to our faces to measure what we are consuming? (And presumably we’ll have to purchase carbon credits to account for the carbon dioxide we add to the atmosphere when exhaling).

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