ROCKMAN wrote:Timo - Are you referring to risk management? Unfortunately folks can develop a false sense of low/no risk by focusing on technology and complex regs. In my 38 years rarely has tech failure caused a major problem. It invariably resulted from someone making a bad decision.
Timo wrote:RMA is the Resource Management Act. I spent a few months studying this in a self-taught fashion, so i certainly can't claim to be any authority on the Act, but basically it requires all development in NZ to have a minimal or neutral econological impact on the greater ecosystem. That's my understanding of it, but that may not actually be correct. Graeme or Kiwichick should have a better explanation.
A new report into climate change paints a picture of New Zealand with more extreme rainfalls, increased heat stress in animals and a growth in forestry production.
The Ministry for Primary Industries (MPI) report Four Degrees of Global Warming posits a "what-if" scenario of what conditions will be like for the primary sector in 2100 based on two current global climate models.
One of the models, from the Canadian Climate Centre, predicts a 4.4degC increase in the national average temperature, while a German model theorises a smaller 3.1degC change.
The MPI report is based on a 4degC temperature increase.
Temperature rises are believed to be most pronounced in inland and eastern areas, with the largest seasonal temperature rises in winter and the smallest in summer.
"Summers with 20 or more days of conditions that induce heat stress are projected to become more widespread," the report says.
f renewables are going to grow their share of generation, we’ll obviously need to build new plants. So the first question is, can we build enough capacity to match current demand, and allow for future growth?
According to Mason et al:
Recent resource estimates published by… EECA indicate near-term potential for 6600 MW of new wind generation, 4680 MW of new hydro generation, 635 MW of new geothermal generation and 3090 GWh/ year of electricity from woody biomass
That compares to current capacities of 622 MW of wind, 5,254 MW of hydro, and 731 MW of geothermal. Theoretically, we could develop twice as much hydro and geothermal as we have now, or ten times as much wind. In practise, we’d run into issues with the wind, since it can’t be relied on to blow when you need it – but Mason et al refer to several studies which suggest that “penetration levels well above 20%” are possible. That’s still three or four times what we have now.
Even the woody biomass contribution could be fairly substantial. New Zealand currently uses around 43,000 GWh/ year, so biomass could account for up to 7% of that.
Overall, growth in capacity isn’t an issue – there’s plenty of room for growth, although some of those plants will cost more to build than others. The other question is:
Can an all-renewable system meet demand in peak periods, or in “dry years”?
This is the tricky part. Electricity demand fluctuates quite a lot during the day, and during the year. We use more electricity in the evening, as people get home from work, shower, flick on the TV, and start cooking dinner. We also use more power in winter, mainly for extra heating. An all-renewable system would need to cope with both these patterns, as well as any unexpected demand surges.
The other issue is that hydro generation forms the backbone of our power system. For those plants to operate at full blast, we need good rainfall, running into the rivers which fill up the hydro lakes. Every now and again, we get a “dry year” with rainfall that is well below average. This means that we can’t generate as much hydro electricity.
“Dry years” aren’t that dry – the difference between our best year for hydro generation (2004) and our worst recent year (2001) was around 20%, or 5,000 GWh – but that’s still quite a bit of slack which other plants need to take up. And the crunch comes during winter, when demand is high and supply is struggling to match it.
So, how do you design an all-renewable system? You let the wind turbines turn whenever they can, as that’s essentially free electricity. Most of the geothermal plants will also run constantly. These are your “base load” plants. Hydro is also part of the base load, but the aim is to use as little of it as possible, since that’s the easiest form of energy to store for when you might need it later.
You also need “peaker” plants, which only run during higher demand periods. Hydro plants can actually gear up and down their production pretty quickly, so they’re a good option. To do this, they need to have “stored energy” ready to go – water reservoirs or lakes.
From Mason et al: “A significant characteristic of New Zealand’s hydro generation system is the relatively low energy storage capacity. When all lakes are full this amounts to approximately 34 days reserve at peak winter demand (approximately 130 GWh/d in 2007), assuming zero inflow”.
For an all-renewable system, you’d need to build a bit more storage. You might consider a “pumped-hydro energy storage” (PHES) system for some plants. That means that when there’s plenty of electricity available – the wind is blowing, and it’s a beautiful summer day – you use some of the excess hydro energy to pump water uphill, into another reservoir. During high-demand periods, you let it flow down again, delivering more energy to the power plant.
With the American oil giant Anadarko looking like heading home after a second unsuccessful exploratory well, there is renewed hope that the threat to New Zealand’s coasts and climate will now be over.
Both Anadarko and the Government argued that the discovery of oil would bring economic benefit to New Zealand, but their claims have backfired as it now appears that there is no oil to drill for. Leaked information shows that the company found hardrock granite and schist, but little, if any, oil.
"Now is the time to celebrate the good news of this situation," says 350.org organiser John Adams. He says that there is the benefit of avoiding the risk of an oil spill, which would have destroyed an important marine ecosystem.
Greenpeace commissioned a study from the Institute of Technical Thermodynamics of the German Aerospace Centre, which found that “New Zealand can have 100% renewable electricity by 2025”.
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