Extending the V2G Value Proposition: The Missing Transmission, Distribution and National Economic Benefits

Rewiring Aotearoa has made a compelling case that electrification of transport can significantly reduce household energy costs, improve energy security, and support New Zealand’s transition to a renewable electricity system. https://www.rewiring.nz/this-car-can-info

However, the current narrative understates the full economic value of an EV. The adoption of Vehicle-to-Grid (V2G) technology adds more value to owners and to New Zealand.

The greatest opportunity may not be household savings alone, but the ability of V2G to function as distributed network infrastructure, reducing future transmission and distribution investment requirements while simultaneously lowering wholesale electricity costs, improving dry-year resilience, reducing fossil fuel imports and increasing national productivity.

The opportunity cost of delaying V2G deployment is becoming significant. Every year New Zealand delays: Additional network investment is committed based on traditional infrastructure assumptions.

Consumers continue paying scarcity pricing and fossil fuel premiums.
Imported transport fuels drain billions from the economy.
New EVs enter the fleet without bidirectional capability.
The value of existing renewable generation is not fully captured.

The question should no longer be “Can V2G support the grid?” but rather: “Can New Zealand afford not to accelerate V2G deployment?”

The Missing Layer: V2G as Network Infrastructure

Most V2G discussions focus on:

Household savings
Peak demand management
Renewable integration
Energy resilience

These are all valid. However, V2G also represents a fundamentally different way of building network capacity. Historically, networks have expanded through:

Larger transformers
Additional feeders
Substation upgrades
Transmission upgrades

These assets may operate near capacity for only a few dozen hours per year. V2G offers an alternative. Instead of building infrastructure to meet occasional peaks, existing vehicle batteries can provide support during those periods.

A 60 kWh EV battery is approximately equivalent to 4.5 residential batteries and is half the price. Unlike a stationary battery the EV battery has already been purchased for transport. The network effectively gains access to storage capacity without funding the battery itself.

Distribution Benefits Are Likely Underestimated

Consider a constrained residential transformer. Traditionally:

Peak demand increases.
Upgrade required.
Consumers fund asset through future line charges.

With V2G:

Vehicles discharge locally during constrained periods.
Transformer loading is reduced.
Upgrade may be deferred for years.

The economic benefit is not merely the deferred capital expenditure. The benefit includes:

Lower depreciation costs.
Lower financing costs.
Lower regulated asset growth.
Reduced future line charges.

Consumers benefit twice:

As EV owners receiving flexibility payments.
As electricity consumers avoiding network expenditure.

This “double dividend” is largely absent from current public discussions.

The National Battery Already Exists

New Zealand often discusses large-scale storage projects such as:

Lake Onslow
LNG import facilities
Utility-scale batteries

These solutions all require substantial new investment. The emerging EV fleet is different. The batteries are already being purchased. Assume 1 million EVs with an average battery size 60 kWh. This represents approximately 60 GWh of distributed storage. Only a fraction of that capacity needs to participate to materially affect system operation. The key insight is that V2G transforms an existing transport investment into a national energy asset.

Dry-Year Risk Is Not Just an Energy Problem

Dry-year risk affects:

Wholesale electricity prices.
Industrial competitiveness.
Household disposable income.
Business confidence.

Hydro is effectively New Zealand’s seasonal battery. V2G cannot replace hydro storage. It can improve how hydro is used by reducing daily peak demand:

Hydro releases can be deferred.
Thermal generation requirements fall.
Scarcity pricing becomes less frequent.
Water is preserved for genuinely critical periods.

In this sense V2G complements hydro rather than competing with it. The value of preserved hydro storage has not yet been adequately quantified in public discussions.

The Overnight Renewable Opportunity

A uniquely New Zealand advantage is our generation mix. Geothermal generation operates continuously. Wind generation frequently peaks overnight when demand is low. This creates an opportunity to:

Charge EVs overnight at low cost.
Discharge during morning peaks for a higher rate.
Recharge from solar during the day.
Support evening peaks.

The result is higher utilisation of existing renewable assets. No curtailment or negative pricing. Every additional unit of renewable energy utilised is a unit that does not require fossil fuel backup.

The Fossil Fuel Import Opportunity

New Zealand spends billions of dollars annually importing transport fuels. When an EV replaces a petrol vehicle:

Fuel expenditure remains largely within New Zealand.
Renewable generation utilisation increases.
Exposure to geopolitical fuel shocks decreases.

Recent global events (Straits of Hormuz blocked) have again highlighted the vulnerability of international fuel supply chains. Electrified transport combined with V2G is not merely a decarbonisation strategy. It is an economic resilience strategy.

Why the Economics Differ From Stationary Batteries

A stationary battery exists solely to store energy. An EV battery provides:

Transport.
Backup power.
Renewable integration.
Grid support.
Energy arbitrage.

The same battery therefore generates value from multiple revenue streams. This significantly improves the economic case compared with dedicated grid storage. The electricity system gains access to battery capacity that has been justified primarily through transport economics.

Opportunity Cost of Delay

Perhaps the most important issue is timing. Every year New Zealand delays:

Thousands of EVs enter the fleet without V2G capability.
Bidirectional charging standards remain immature.
Networks continue planning traditional upgrades.
Consumers continue funding infrastructure that may later become avoidable.

The cumulative cost of delayed adoption could exceed the cost of enabling V2G. This opportunity cost should be explicitly recognised in policy analysis.

Recommendations

Rewiring Aotearoa should broaden its V2G analysis to include:

1. Transmission and Distribution Deferral Value

Quantify:

Deferred feeder upgrades.
Deferred transformer upgrades.
Deferred substation investment.
Deferred transmission investment.

2. Dry-Year Value

Model:

Hydro preservation.
Reduced thermal dispatch.
Reduced scarcity pricing.

3. National Fuel Import Reduction

Quantify:

Reduced petrol and diesel imports.
Improved balance of payments.
Increased domestic economic activity.

4. Opportunity Cost of Delay

Estimate:

Lost network savings.
Lost wholesale market benefits.
Lost consumer benefits.
Lost resilience benefits.

5. Policy Acceleration Pathway

Evaluate:

Mandatory V2G readiness for new EVs.
Incentives for bidirectional chargers.
Flexibility procurement obligations for EDBs – pay EV owners to inject electricity at peak times.
Dynamic export pricing and local flexibility markets.

Conclusion

V2G should no longer be viewed simply as an EV feature. It is emerging as a form of distributed national infrastructure. The value proposition extends well beyond:

Household energy savings.
Renewable integration.
Emissions reduction.

The larger prize is a lower-cost electricity system, reduced fossil fuel dependence, deferred network expenditure, improved dry-year resilience, and a more productive New Zealand economy. The opportunity cost of delay is increasing every year.

Accordingly, V2G should be evaluated not merely as a transport technology or household energy technology, but as a strategic economic asset capable of delivering benefits across the entire New Zealand energy system.

V2G Benefits