About MyGridNZ

Welcome to MyGridNZ

The way that electricity is generated in Aotearoa New Zealand changes every minute of every day. Our power must respond to rainfall in hydro catchments, wind across Cook Strait, and every flick of a switch from Kaitaia to Invercargill. The grid is also evolving, with gas-fired generation gradually giving way to expanded wind, solar and battery storage.

MyGridNZ charts all of this change. It is an independent platform giving information and analysis of energy and carbon emissions in Aotearoa New Zealand. I established MyGridNZ to provide a source of unbiased information about these issues and let you, the public, form your own opinions on our energy future based on the data.

It provides analysis of the volumes of electricity being produced and consumed, and where that electricity comes from — using historical data published by the Electricity Authority's Electricity Market Information (EMI) portal. Blogs by myself and guest authors also provide the latest insights.

The analysis is not limited to the volumes of electricity. MyGridNZ also charts carbon emissions from electricity – of critical importance for a country with climate targets.

My Clean Power 2030 Blueprint shows an alternative electricity mix. This alternative is a simulation of a different mix of generation that would meet Aotearoa New Zealand's clean power objectives. It is simulated on the website and includes a role for solar and batteries on our homes – as I strongly believe that homes are the power stations of the future.

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Carbon Targets

Aotearoa New Zealand has set an aspirational goal of 100% renewable electricity by 2030. MyGridNZ tracks progress against this goal using a carbon intensity threshold consistent with a near-fully-renewable grid. Carbon intensity data is based on IPCC life-cycle emissions factors applied to the generation mix.

Grid Data

Aotearoa New Zealand electricity comes from a number of sources — hydro, geothermal, wind, gas, solar and others. The amount each produces is adjusted in real time in response to demand, reservoir levels, wind conditions and equipment availability. MyGridNZ summarises generation from each source in real time on this website.

Data is sourced from the Electricity Market Information (EMI) portal of the Electricity Authority. This data is licensed for re-use under the Creative Commons Attribution 4.0 International licence (CC BY 4.0).

Solar Data

Solar generation from embedded (distributed) rooftop systems is not fully captured in wholesale metering data. MyGridNZ incorporates estimates of embedded solar generation derived from capacity and irradiance data.

The solar generation figure is an estimate and will be refined as more data becomes available.

Carbon Dioxide Equivalent Estimation

Carbon Dioxide equivalent is the combined effect of all greenhouse gases (not just CO₂) from different electricity generation sources over their lifetime. Where CO₂ figures are reported, values are taken from the Intergovernmental Panel on Climate Change (IPCC): Life-cycle greenhouse-gas emissions of energy sources.

Note that some official sources use lower values for the carbon intensity of biomass — I apply IPCC/independent analysis in my figures.

Throughout I use the "median" figures from the following table:

Technology	Median Carbon Factor (gCO₂eq./kWh)
Coal	820
Gas	490
Biomass	230
Solar PV — Utility Scale	48
Solar PV — Rooftop	41
Hydropower	24
Wind — Onshore	12
Wind — Offshore	12
Imports (average)	300
Storage	24

Solar on New Homes

MyGridNZ advocates for solar panels on all new homes built in Aotearoa New Zealand. Rooftop solar combined with battery storage can make every household a small power station, reducing strain on the grid and cutting household energy bills.

System Cost (LCOE) Methodology

The 2030 Blueprint page shows the average cost of generating one megawatt-hour of electricity delivered to consumers — a System Levelised Cost of Electricity (LCOE). This answers: if you had to pay for every asset in today's (or tomorrow's) grid, what would each delivered MWh cost on average?

LCOE figures are drawn from MBIE's Interactive Levelised Cost of Electricity Comparison Tool (2021) and UK DESNZ Electricity Generation Costs 2025 benchmarks converted to NZD at the prevailing exchange rate, with adjustments for current NZ cost conditions. All figures are in 2024 NZD, central estimates for a 2030 commissioning year. MBIE electricity statistics are licensed under a Creative Commons Attribution 3.0 New Zealand Licence (CC BY 3.0 NZ).

Technology	LCOE (NZD/MWh)	Source / Notes
Wind (onshore)	170	UK DESNZ £80/MWh converted to NZD; consistent with MBIE upper range
Solar PV (utility)	125	UK DESNZ £60/MWh converted to NZD; MBIE range 70–128 at conservative CF
Geothermal	85	MBIE median 84 NZD/MWh; NZ-specific resource
Large hydro	45	MBIE pondage median 45 NZD/MWh; existing fleet largely amortised
Battery storage (BESS)	190	UK DESNZ £90/MWh converted to NZD; per MWh dispatched
Wood / biomass	120	NZ-specific estimate; waste wood at existing mills (Kinleith, Norske Skog)
Coal	130	MBIE median inflated ~15% for current costs
Diesel (reciprocating)	475	MBIE median 474 NZD/MWh
Gas CCGT	load-factor dependent	See formula below; capped at $400/MWh

Gas LCOE is load-factor dependent. A gas plant's fixed capital costs are spread over however many hours it runs — a plant running at 10% of capacity costs far more per MWh than one running at 80%. The formula is calibrated from MBIE's CCGT and gas peaker data points, inflated ~25% for current NZ gas market conditions (declining Pohokura field, tighter supply):

LCOE_gas = 31 / LF + 62   (NZD/MWh, LF = load factor 0–1, capped at $400)

At 80% load factor this gives ~$100/MWh; at 20% (peaking) ~$217/MWh. The variable component covers NZ gas fuel costs, NZ ETS carbon costs, and variable O&M. The cap reflects capacity market and storage effects limiting extreme scarcity pricing.

Curtailment cost. Under the Blueprint, some wind and solar generation is curtailed when output exceeds both demand and available storage capacity. Those turbines and panels still have to be built and financed, so the full generation cost is included even for curtailed MWh — spread across electricity actually delivered to consumers:

System LCOE = Σ(LCOE_i × GWh_generated,i) ÷ Σ(GWh_delivered,i)

The Blueprint simulation gives direct delivery figures for wind and solar. These are scaled up to total generated using the curtailment model (dividing by the direct-delivery fraction), so the cost numerator captures all generation including the curtailed portion.

Useful curtailment. The third LCOE figure assumes that 50% of curtailed renewable energy is usefully consumed — for example, charging electric vehicles, running heat pumps, or producing green hydrogen — rather than being wasted entirely. Since those MWh are already paid for (the turbines exist regardless), every curtailed electron that finds a use reduces the average cost per useful MWh. This scenario is important in the context of decarbonisation: using low-carbon curtailed electricity to power vehicles displaces petrol and diesel, compounding the carbon benefit beyond the electricity sector.

Funding

MyGridNZ is mostly funded through my own pocket and via kind donations.

MyGridNZ is kindly supported by the Durham Energy Institute (DEI). The DEI have no influence on the material which I publish.

Durham Energy Institute draws on the expertise of world-leading researchers across Durham University with a membership spanning departments in Science, Social Science and Humanities. We emphasise a 'Science and Society' approach to energy which tackles the societal aspects of energy technology generating insights into how technology is shaped by, adopted by, and influences society. We also undertake research developing new energy technologies and solutions for the benefit of society including renewables generation (wind, solar, geothermal, bio-fuels) and integration, transmission and distribution, smart energy systems, carbon capture and storage, and nuclear fusion.