Can Australia achieve 100% renewable energy by 2020?

The Zero Carbon Australia 2020 Project is a detailed and costed blueprint for a transition to a zero-emissions economy in 10 years using proven, commercialised technology. Its purpose is to show the Australian public and decision-makers that reaching a zero-emissions economy is ready to be implemented and only awaits government sign-off. It aims to initiate urgent efforts to mitigate the risks posed by global warming and to describe the infrastructure and resources required to reduce Australia’s carbon emissions to zero in the medium term.

Peer-reviewed climate science calls for reductions in atmospheric CO₂ concentrations from today’s level of almost 390 ppm to less than 350 ppm. Incremental reductions in emissions, such as the 5-25% reductions currently being debated in political circles, will not achieve this target if adopted globally.

The Zero Carbon Australia 2020 Project (ZCA2020) presents a realistic path forward for Australia to achieve a zero-emissions economy, covering stationary energy, transport, industrial processes, buildings, land use and replacement of coal exports.

Stationary energy

This includes all infrastructure that generates and distributes energy to end users and includes electricity generation plants, refining and distribution. In ZCA2020, fossil-fuel-fired electricity generation is replaced by renewable energy, principally concentrated solar thermal with storage and wind generation.

Natural gas and fossil-based liquid fuelled transport is likewise phased out and replaced by transport powered primarily by renewable-generated electricity, with a small use of biofuels in rural areas and emergency services. Eliminating these increases the total national electricity demand from 211 Terawatt hours (TWh) (2007) to 325 TWh (2020), excluding off-grid generators. However, by employing greater efficiency in the use of energy and by minimising the use of inefficient internal-combustion engines, the total amount of energy delivered in Australia falls from 3834 Petajoules (1065 TWh-equivalent) in 2007 to 1643 Petajoules (456 TWh-eq) in 2020. In the building sector, for example, energy-saving measures employed in ZCA2020 include a switch to heat-pump heating and insulation of all commercial and residential buildings.

Overall, 60% of electricity supplied by a 100% renewable stationary energy sector will be provided by concentrating solar thermal with molten-salt heat storage and 40% by wind power. Photovoltaic solar panels will also produce electricity during sunny periods, and hydroelectricity and crop residual biomass will provide back-up energy when needed.

24-hour solar electricity

The backbone technology for Australia’s 2020 electricity generation system is concentrating solar thermal (CST) power towers with molten-salt heat storage. This technology is already being installed in Spain and the USA. Residential and commercial photovoltaic systems will still be used to reduce demand on the electricity grid during sunny periods.

With a dozen geographically diverse sites, CST provides readily available (dispatchable) electricity 24 hours a day. These 24-hour baseload solar plants concentrate sunlight onto a receiver and store the generated heat in molten salt at 565-650°C. The stored heat is used to boil water, creating steam to drive conventional turbines, and is available day or night. When turbines are idle, heat is taken off the ‘cold’ 290°C salt storage tank to keep the turbine seals warm, allowing fast starting. This capacity for both base-load and fast-start dispatchable power generation allows CST plants to address and profit from demand peaks.

CST power towers with molten-salt heat storage are able to operate at 60-100% of maximum turbine output for up to 90% of the hours each year, with very few maintenance shutdowns. Air cooling of the power cycle reduces water requirements to less than 12% of a conventional thermal (eg, coal) power plant. Australia can also supply the concrete, steel, glass and expertise to construct these plants, creating many jobs in the process.

Twelve sites around Australia have been chosen for CST installations, each with 3500 MW electrical (MWe) capacity, giving a total of 42 GWe. Each installation consists of around 20 power tower modules, allowing for these to be scaled up from 50 MWe in early installations to 217 MWe later. Each module consists of a molten-salt power-tower system with steam turbine and enough mirror field to provide thermal heat for both daytime power generation and stored energy for night-time generation. The storage is sufficient for up to 17 hours generation at full power.

Twenty percent of Australia’s CST systems will be installed in four years (2011-2014), equating to 8700 MWe capacity, with storage to provide 55 TWh/year. This is 17% of the projected total 2020 national stationary energy demand. As production capacity increases, the remaining CST plants will be constructed from 2015-2020.

Once 8.7 GW of molten-salt power-tower capacity has been installed globally, solar thermal power will provide electricity at a cost competitive with conventional coal power (~5 cents/kWh).

Wind generation

On-shore wind resources are Australia’s second strategic advantage in renewable energy. Wind power is the cheapest of all clean energy sources and is technologically mature. ZCA2020 couples wind with CST/molten-salt storage to provide dispatchable, lowest-cost and emissions-free electricity. Wind power is dispatched to the grid whenever it is available and power generated from CST/molten-salt storage makes up the difference to meet demand at all times. Approximately 48 GWe of installed wind turbine capacity (~8000 x 6 MWe turbines) is proposed in addition to Australia’s current 1.5 GWe. ZCA2020 demonstrates that 40% of Australia’s annual electricity demand, 130 TWh/year, will be generated by wind turbines.

Transmission upgrades

Upgrades are necessary to deliver the CST and wind power to demand centres and achieve stability in the electric grid by allowing greater and more flexible transport of electricity around Australia. ZCA2020 costings include construction of electrical transmission lines. A 500 kVAC transmission system will connect new power stations located near populated regions. High-voltage direct current is to be used for low-loss long-distance transmission from remote areas to demand centres, increasing supply security and decreasing transmission losses.

Natural gas

ZCA2020 acknowledges that the elimination of natural gas as an energy source is a challenge, however, it can be reduced by improving building energy efficiency (by 20%), switching to electrical sources of energy (eg, High-efficiency heat pumps and induction cooktops), electrical heat and direct solar co-generation in industrial settings.

Levelling demand peaks

The present Australian electricity supply system experiences large differences between demand peaks and troughs. For much of the year, energy supply systems operate far below their maximum capacity while, at peak-demand times, the system is stressed, sometimes to the point of failure.

Under ZCA2020, demand will peak in winter, due to the requirements of electrical heat pumps which will offset existing inefficient gas-fired heating. For optimal efficiency, a demand profile much flatter than the present will be achieved via a ‘smart-grid’ to schedule off-peak vehicle battery charging, off-peak heat-pump solar hot-water boosting and off-peak heating, cooling and refrigeration. Smart-grid technology will help shift energy use from peak to off-peak times, thereby stabilising demand.

Investing in the transition

ZCA2020 proposes that $35-40 billion per year be invested over a 10-year period to transition to a 100% renewable stationary energy sector. In addition to savings generated by ending oil imports, the costs ordinarily incurred under a business-as-usual (BAU) scenario, such as coal, gas and water costs, as well as fossil-fuel plant replacement and upgrade costs and other operating and maintenance costs, would be eliminated.

ZCA2020 involves a net additional investment of AU$200 billion from now until 2050 (when the renewable-energy infrastructure will need replacing or upgrading) compared with BAU. However, this is without including any future carbon price or escalating oil prices which, if included, show ZCA2020 as economically favourable. Given the urgent necessity of a 100%-renewable economy within the given time frame, this is a sensible expenditure.

Resources required

ZCA2020 also examines the resources and the scale-up of manufacturing capacity required to achieve the transformation. Given the amount of economic activity already deployed towards using concrete and steel resources elsewhere, it will be within our capability to direct a proportion of effort towards ZCA2020. This will create over 15,000 jobs at the peak of construction, plus an ongoing 50,000 jobs in operations and maintenance.

Conclusion

ZCA2020 concludes that there are no technological impediments to transforming Australia’s stationary energy sector to zero emissions over the next ten years. The costs of transformation are adequately offset by savings made from shifting away from the BAU scenario. No resource constraints were identified. With adequate societal and political commitment and regulatory support, the goal of an efficient and competitive zero-emissions stationary energy sector is well within Australia’s reach.