Zenaji is a Melbourne-based solar battery technology company that manufactures lithium titanate batteries. It’s chief technology officer, Charles van Dongen, offers a personal perspective on how Australia can achieve its goal of net-zero emissions by 2050.
The world is undergoing one of the biggest societal and technological revolutions since the introduction of electric power distribution at the turn of last century. Back then, society moved from a predominantly rural decentralised industrial environment to a large city-based society with centralised power generation. It was a society based on the infinite abundance of both coal and oil with not much thought for future consequences.
Today, we are moving towards a more diversified mix of technologies, both centralised and decentralised, with additional changes of how and when we use energy. Even in the past two years, COVID-19 has educated us to the possibility of working from home where possible, thus significantly reducing transportation energy.
Big steps towards net-zero emissions
While the much-talked-about carbon credits and taxes are useful tools that can encourage industry to reduce emissions, they are prone to “garbage in/garbage out” whereby a good accountant could make the numbers dance to whatever tune they desire.
Right now, I hear Australia is reducing emissions yet I see more 4WD cars on the road, bigger houses in the suburbs, and more people increasing their consumption. What is needed is a more direct method of reducing emissions, including reducing your existing demand.
Architectural designs
More than 40 per cent of wasted domestic energy is architecturally related. New houses should be designed with solar direction in mind, with fully insulated walls and roof; double-glaze windows; reverse-cycle air-conditioning; heat pump hot water (that eliminates gas); induction stoves; LED lighting; and high-efficiency modern appliances.
Similarly, people need to be encouraged to update existing houses to this standard, including planting trees to create a microclimate and absorb carbon.
Home insulation is critical, despite the pink batts debacle of several years ago in Australia. It is still the quickest and most cost-efficient way to reduce energy loss and keep out heat.
Efficient transport
When selecting a vehicle, go for hybrid or pure electric, although if electric is your choice, ensure you buy power from a green source or have enough panels on your roof to generate the car’s power. For an average 45km travelled per day, you need 8kWh of generation, or six 375W solar panels feeding into the grid or directly charging your car.
Other green options include carpooling; working from home; using public transport; and walking, running and riding – all work places need to be fitted with showers!
One controversial opinion is that we need more freeways to reduce the stop-start nature of city traffic, and more pay car charge points at work locations that bill directly to your home solar array with an account fees collection system.
Conventional petrol-powered vehicles are intrinsically a low-efficiency use of energy with less than 30 per cent of energy actually used for moving the vehicle. Electric vehicles offer an overall energy transfer efficiency of around 85 per cent.
There is much talk about fast-charging stations, but little realisation that positions within each state that can support the huge power-transfer requirements are very limited. To be economical, you need to be able to support 10 vehicles at any one time, all getting a 15-minute recharge.
Given the battery capacity of such vehicles is around 80kWh, this represents a load of more than 3MW. Such loads can only be supported on our 220KV terminal stations (and higher). This limits large fast-charging stations to a few locations unless expensive battery storage on the stations’ sites are used. It is more likely that the bulk of electric vehicle charging will be performed at home during the night at off-peak rates.
In addition, all parking meters and workplace car parks should become EV charge points. The key to the network being able to cope with the loading will be slow charging at around 1kW for an eight-hour period. This will enable an average EV to travel 45km.
Electric vehicles are only green if their energy comes from renewable sources. An EV powered from our existing coal-fired or gas network actually contributes the same amount of CO2 than a conventionally powered car. Although it does clean up other emissions such as nitrogen oxides, sulfur dioxide and airborne particulate matter.
To meet the 8kWh energy requirement to cover a 45km journey, every EV user will need to offset their vehicle energy requirement with rooftop solar panels. If the energy is stored for the night-charge cycle, the user would need around six to eight 375W solar panels. If the user relies on the grid to store the energy, they would need at least twice this number of panels to allow for the net import/export tariff differences. This would need to be repeated per vehicle.
To enable transfer of electricity, an energy charge accounting system needs to be developed to pay for the source of the energy and allow for transfer from the home array to a vehicle charge point.
Create a national/international grid
We sometimes hear distorted reports in the media about solar panels causing local overvoltages. If the grid-tie inverters are overvoltage restricted, it is hard to understand how this could occur. In addition, overvoltages are very common at night in low-energy usage times. I believe the use of transformer taps at substations are deliberately pre-set high to ensure higher voltages, and thus higher billed revenue. On resistive loading, a five per cent increase in voltage results in a 10 per cent increase in revenue.
We urgently need to connect all the state energy grids, but initially a high-voltage direct current (HVDC) line from Perth to Port Augusta, in South Australia, is needed. Australia also needs a separate HVDC line from Gippsland, in Victoria, to Benmore, on New Zealand’s South Island.
Doing this, we can match the peak power generation times to the peak usage times by a maximum of around five hours’ discrepancy. In addition, the establishment of these links will greatly reduce power fluctuations and strengthen the grid against outages.
I note there is an existing proposal – the Australia-Asia Power Link – to connect Australia to Singapore via 4500km of HVDC transmission lines, which is a fantastic initiative.
Expansion of rooftop solar
Contrary to the erroneous claims of government and electricity suppliers since the AS 4777.2 inverter standard became effective in October 2016, inverters have been limited to a 255 VAC output and consequently are incapable of producing overvoltages. The high distribution voltages that are sometimes reported are the result of distribution companies deliberately increasing transformer taps and disproportionately increasing their revenue.
There is much talk by various state energy ministers who have been misled that they will need to reduce tariffs paid back to customers to reduce this overvoltage issue. In reality, they need to crack down on distribution companies to encourage them to reduce transformer taps at substations.
In addition, the linking of the state and international grids, as described, will enable the significant increase of domestic roof generated solar.
The Clean Energy Council states 23.5 per cent of Australian rooftops have solar PV arrays, yet only around 6.6 per cent of Australia’s electricity generation comes from solar PV on rooftops. Part of the reason is most rooftop arrays are undersized and need to increase to fully cover an all-electric household, including hot water with the use of heat-pump technology; air-conditioning; and the charging of electric vehicles.
In many instances, this may also require the installation of 3-phase connections so the total export can be increased to above 10KW. An advantage of this approach is more of the roof should be covered with solar panels, thus creating an additional thermal barrier in summer to reduce cooling requirements.
Hydrogen
Hydrogen is a great storage medium with high portability, and it offers very fast recharge capability. What is often forgotten is that hydrogen is not a fuel – it is an energy storage medium with a round-trip efficiency between 30 per cent and 50 per cent. It is highly suitable for applications that demand fast charging, as well as the military and where hydrogen is obtained from waste sources, or where there is excess solar generation capacity.
However, if hydrogen is obtained from non-renewable sources, it will in fact produce more CO2 due to its low round-trip efficiency.
Batteries
There are many different chemical compositions of battery types and they all have their uses. For example, even lead acid is still probably the most cost-efficient medium for intermittent usage power storage. In electric vehicles, lithium iron phosphate batteries represent the best compromise, but for domestic and industrial long-term high-usage cycling, the most suitable technology is lithium titanate in terms of safety, temperature tolerance, longest lifespan and high-cyclic capacity.
The issue that holds back lithium titanate is its upfront cost and, to a lesser extent, its size and weight – although that is not an issue for stationary usage. Lithium titanate cells are the only battery technology that can pay off its cost within its useful lifetime. In fact, it can pay off as much as four times the cost during its lifetime.
With Australia’s state governments currently actively discouraging customers from putting energy back into the grid by reducing tariffs, many people will soon opt to store excess energy and use it at night. Many people may choose to completely disconnect from the grid again by purchasing more batteries.
Pay in tariffs
Australian state governments reducing the pay in tariffs back to consumers is conducted under the false pretence that solar power is overloading the system. This trend will continue to make it less economical to pay off solar panels quickly. In addition, it will encourage consumers to go off-grid and put excess solar energy into batteries.
Properly used and interconnected, the best and cheapest battery is still the national grid.
Rooftop solar panels
Solar panel prices have dropped considerably during the past few years and are stabilising as they are getting close to raw material costs. Solar panels and the use of a basic grid-tie inverter is the single most cost-effective purchase to reduce your carbon footprint and reduce your energy bills to zero. Currently the payback period on a well-designed system is three to four years.
Food choices
As a society, we should be focusing on sustainable food and the need to reduce meat from our diets, choosing locally sourced food to reduce transport. We should also encourage diets that reduce methane emissions – again, less meat – and grow our vegetables at home.