By George Jones
Whenever electricity is taken from one place to another, some of it is lost, ultimately as heat.
In New Zealand, this waste electricity constitutes about 6 or 7 percent of the electricity generated; enough to power the entire Greater Wellington area. In other countries it is usually larger, up to three or four times NZ’s percentage. The industry keeps track of the losses, as there are meters at most points of sale. Ultimately the consumer pays for these losses, but not at the retail price. It is to everybody’s advantage to keep the losses as low as possible. The industry could charge retail if they could deliver more to the consumer, and the consumer would not have to pay for something they do not receive.
What causes this electricity loss?
This loss depend on several factors, such as the size and material of the conductors, the frequency, the values of the current and voltage and their relative phase. There are complicated relationships between these factors.
For example, the resistive loss is proportional to the square of the current in the conductor. Doubling the current thus causes a four-fold loss of electricity. The actual loss is greater than this figure, as the resistance of the wires increases with temperature. If the current is reduced by, say, 10%, then the loss reduces by 19% from the square law. Of course, the reduction will be greater as the wires will be cooler.
New Zealand’s electricity has relatively low losses, due to the excellent plans of the designers, who allowed room for growth. The DC Cook Strait cable has a relatively low loss in electricity. The original decision to use 50 Hz as opposed to 60 Hz was undoubtedly the right one.
However, certain parts of the transmission and distribution network need to be upgraded sometimes. For example, the cables feeding the Nelson and Tauranga regions needed to be upgraded as the population increased. To this end, new transmission lines into Auckland were built.
How can we reduce these losses?
One way to reduce the losses is to not move electricity long distances, by generating it close to where it is used. Solar panels are one solution, wind another. As we have generally run out of rivers close to large cities, hydro-generation is less viable, and geothermal power is still a good distance from Auckland. Carbon-based generation is now way too expensive, and anyway we signed the Paris Agreement to limit this. And let’s not talk about nuclear.
Wind is now the least expensive and reducing in price, but only if the turbines are very large to capture the higher winds. This generates opposition from local citizenry because of visual pollution.
Solar in next lowest in price, with a downward pricing trajectory steeper than wind. Soon solar will be the least expensive option of all. The world has caught on about solar, with a lot of countries now installing very large amounts, such as China and India, catering for a substantial fraction of the world’s population.
When solar panels are added to a household, there is less electricity entering the premises, so less loss. Furthermore, if electricity excess to the household’s needs is exported, it does not go very far at all; mostly to immediate neighbours. So all the solar-generated electricity is consumed locally, reducing the losses on the distribution and transmission networks.
More solar also means that the transmission and distribution system will not require upgrading nearly as often, even with increasing population and electricity use.
The move pushed by the Electricity Authority for pricing structures to fully reflect where the costs are is to be welcomed. If done correctly, these new pricing structures will greatly increase the value of solar, as the exported solar from a household only uses a few metres of the distribution network to get to its final destination. Moreover, it does not use any of the transmission system. Because of the square law, its existence has a disproportionate effect on the reduction of the losses in the whole system, an advantage to everybody. The result will be an encouragement to householders to add solar.
North Island homes
Solar will be particularly helpful in the middle of the North Island, as in the winter, skiers return to their residences and turn on all the heating at the same time as cooking their evening meal. This means that the losses quickly increase for that evening peak. If solar had been running heat pumps all day, then the peak would be much less as the place would be comfortably warm in the evening; especially if the cooking was done in the daytime using a slow cooker.
The future of solar?
Electric vehicles will add to electricity sales, but with over-night charging, they will contribute little to the loss if handled intelligently, starting charging after the evening peak. Later, daytime charging will be the norm, derived from solar.
Distributed battery storage with solar will reduce the loss further, but the industry will not be happy, because it will be too easy for the householder to go off-grid, especially if the industry starts charging more to get their guaranteed financial return. It will quickly be a death-spiral for the industry.
However if battery storage is integrated with the grid, then with good software control, there would be much less need for distant rolling reserve, so expensive backup could be retired and battery owners paid accordingly. Again, this is a win-win for all involved.
The electrical industry has promoted a lie — that people are being selfish when they install solar panels, and especially those who then disconnect from the grid, penalising the remaining customers, essentially the poor, who cannot afford the panels.
The poor end of town will be incentivised to install solar, with financial wizardry assisting, so that somebody else owns the panels and the electricity is paid for as it is used — just like our current industry business model, but with lower costs. Electricity usage will be time-shifted, and more accessible for the unemployed. This is a classic disruptive technology scenario, seen many times before, with computers, cameras, smartphones and soon, electric vehicles.
Solar has a long way to go, as further research improves the technology and pricing. Predictions are that the price will eventually drop enough that it will be too cheap to meter and will be treated like our use of the roads, with some general payment to cover the infrastructure.
George Jones is a Companion of the Royal Society of New Zealand, retired scientist and adventurer. He lives in a small village in the southern island of Mindanao, in the Philippines, where he is building a solar array to supply renewable energy.