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Generation Technologies - Already in NZ, New Zealand Energy System, New Zealand Oil and Gas

#10 Stop Wasting Our Natural Gas!

We at FreeNRG4NZ believe that with a just a smidgen of political willpower it would be easy to have a 100% renewable electricity generation system in New Zealand. This would bring multiple benefits to our nation and these benefits are discussed elsewhere on this blog.  The main point that we want to make today, is that…

It just does not make sense to burn natural gas to make electricity in New Zealand.

According to the Ministry of Economic Development, in 2010 our gas fired electricity generation plant operated at an overall efficiency of about 50% (note1).  If you compare this figure with the fact that direct water heating by gas can be up to 95% efficient with a continuous flow gas fired hot water system, it serves to illustrate our point – we should be using our natural gas resource for direct use applications – not wasting it to make electricity.

Gas Usage in NZ - The green line has to Go! t's not efficient to use gas to make electricity.

We have an abundant wind resource in New Zealand that could be easily tapped to replace gas fired electricity generation. With more wind, it would be a simple matter to build a pump storage hydro scheme to provide electricity storage (note 2) with such a pumped storage plant also meeting the peaking demand that gas generated electricity should theoretically, but is not always, solely be used for.

When our gas resource is all gone, the current plan in the back drawer by Contact and Genesis is to build a LNG gas import terminal in New Plymouth.  This simply makes no sense at all.  Why should New Zealanders pay for gas to be imported to make electricity when we could be making electricity for free, today, for ourselves?  And no doubt by the time this LNG import scenario occurs, the market will be extremely volatile due to global Crude Oil production constraints.  Come on New Zealand, lets get serious about installing more renewables now (note 3), the price is right – let us stop wasting gas to make electricity.

This is a really stupid Plan B


Note 1: Ministry of economic development – energy balance spreadsheets 2010: Net Energy: Gas Used for Electricity Generation = 55.76PJ, Electricity Output to Grid from Gas = 33.14 [59% efficiency], Gross Energy: Gas Used for Electricity Generation = 62.58PJ, Electricity Output to Grid from Gas = 33.14 [52% efficiency].  In addition, the electricity generation numbers quotes here are “at the plant” figures, we must allow for about 7% of electricity transmission losses to get the power to your house or the site for direct use, not to mention the inefficiencies in electrical use in the appliance.  While combined cycle gas fired plant is somewhat more efficient than normal gas plant, the figure of 55% we have calculated here represents the fact that New Zealand operates both types of generation equipment, Otahuhu A is a traditional gas fired plant, while Otahuhu B is a combined cycle plant for example.

Additional wind and a pumped storage scheme is the obvious solution for NZ to replace gas generated electricity

Note 2 : The technology already exists to store electricity from renewables in the form of pumped storage, while pumped storage systems typically operate at 75% to 80% efficiency, this figure is still a lot better than the 50% efficiency achieved by burning gas to make electricity / peaking electricity.  And since wind, unlike gas can not be used for other purposes, like making liquid or compressed gas fuels, for heating water directly or even sold to others, the small amount of energy that is lost in the storage of wind power via a pumped storage solution is not really lost at all. That, 25% extra wind that is used to overcome friction losses in the pumping and generation aspects of a pumped storage scheme, would simply have blown over our hills unable to be used by future generations in any case.  Also, since New Zealand already has a wonderful hydro resource, by installing more wind generation, the overall drawdown of our hydro storage would be much less meaning that the “dry year” problem (that advocates of our wastefull gas fired electricity always trott out), would not be as severe.

Using Natural Gas for Direct Applications is 95% efficient, using it make Electricity is 50% efficient.

Note 3 – FreeNRG4NZ is predicated on the fact that the technology already exists, NOW, to go 100% renewable electricity in New Zealand. While we are supportive of other renewable generation technologies such as solar PV and tidal we believe that the only proven renewable resource currently available is wind. We believe geothermal opportunities in New Zealand will be more or less exhausted in the next 5 years, and large direct hydro river scheme opportunities are also limited.

Reference File – Ministry of Economic Development – Energy Data File

Typical thermal / theoretical efficiencies for making electricity


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Contributions sought for this blog > If you have ideas on how New Zealand can move towards 100% renewable electricity as the first step and then onward towards full energy independence - contact us. Lets all work together to get the conversation moving more.


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