Working Papers
Driving down personal aviation demand (presentation)
This paper investigates the potential long-run effects of autonomous and electric vehicles, and a carbon tax, on personal domestic aviation demand in Australia. We estimate a discrete choice disutility model with two travel modes — car and air — using Australian National Visitor Survey data and Bayesian priors. We use multiplicative Fréchet errors, consistent with a constant elasticity of substitution utility function for a representative consumer of both modes. An elasticity of substitution of almost 4 replicates the observed transition to air travel as distances increase. Combining in turn electrification, autonomy, the use of overnight robotaxis, a 10 kph increase in average car speeds, and an AUS$200/tCO2e carbon tax leads to air passenger reductions of 4%, 17%, 21%, 26% and 42%, respectively. Reductions are highest for shorter flights, so aggregate emissions do not decline as much as passenger numbers, while the number of aircraft trips declines more.
Wiskich, A. Perfect so far? Substitutability between wind & solar and dirty electricity generation.
Wind and solar are driving the clean transition in electricity: this paper uses panel data to investigate how these technologies substitute with dirty (fossil fuel) electricity generation. Production functions with a constant and a variable elasticity of substitution are estimated. Results suggest a higher elasticity of substitution than previous estimates, aligning with long-run analysis from electricity dispatch models and assumptions often made in economic models. Little evidence is found of the elasticity decreasing so far. However, the uptake of wind and solar decreases the utilisation rates of dirty capacity.
The elasticity of substitution parameterises how easily wind and solar can replace fossil fuels in a clean transition of electricity supply. I infer this parameter from some electricity dispatch model literature and present a simple dispatch model replicating the key result: a high elasticity for a low share of wind and solar, which decreases as this share rises because integrating intermittent technologies becomes increasingly difficult. Such decreasing substitutability may imply greater costs from regions adopting different carbon prices.
Peer-Reviewed Publications
Wiskich, A. (2025) How can long-distance battery-powered container ships stack up? A speculative Asia-Europe illustration. Research in Transportation Economics. (linked-in article)
Are batteries too costly and not sufficiently energy-dense for long-distance shipping? We consider a battery-powered container ship on a round trip between Asia and Europe under two speculative assumptions. First, in addition to a battery-on-container-ship (“on-ship”) approach, we study an “off-ship” concept where a dedicated battery vessel can power the ship en route. Second, we allow (dis)connection of battery vessels and charging at sea. We describe an economic model that optimises ship speed, number of charging stops at sea and battery capacities for a hybrid (fuel/battery) container ship. Our main insights: (i) the off-ship approach allows greater flexibility and partial electrification at higher battery costs, (ii) optimal speeds increase and vary depending on the route segment with battery-powered propulsion, and (iii) battery uptake is more sensitive to battery costs than energy density. We hope these insights promote research into the technical feasibility of the off-ship approach.
Wiskich, A. & Speight, R. (2025) The global decarbonisation potential of Synthetic Biology. Global Change Biology (preprint)
Synthetic biology-based technologies can impact many sectors and are often targeted at improved environmental outcomes. Here, we discuss synthetic biology applications that can lead to long-term decarbonisation and quantify the potential using a top-down approach. We find that promoting the restoration of agricultural land to natural ecosystems has the most potential. Boosting food production by raising agricultural productivity or producing alternative foods promotes this restoration by reducing agricultural land requirements. The carbon stocks in agricultural soil can also be increased. Reducing emissions in agriculture, industry and transport represents the second largest potential. Geoengineering-based mitigation and sequestration in nature is third. We outline what scale may be required for some technologies to achieve one gigaton (GtCe) of decarbonisation. We also highlight differences in the sensitivities of these technologies to carbon prices, agricultural land prices and greater circularity in economic processes. We hope that our high-level view of the decarbonisation potential of different synthetic biology application areas helps identify priorities and promotes the long-term contribution of these technologies towards climate change mitigation.
Access to finance is a major barrier to clean innovation. We incorporate a financial sector in a directed technological change model, where research firms working on different technologies raise funding from financial intermediaries at potentially different costs. We show that, in addition to a rising carbon tax and a generous but short-lived clean research subsidy, optimal climate policies include a clean finance subsidy directly aimed at reducing the financing cost differential across technologies. The presence of an endogenous financing experience effect induces stronger mitigation efforts in the short-term to accelerate the convergence of heterogeneous financing costs. This is achieved primarily through a carbon price premium of 39% in 2025, relative to a case with no financing costs.
Social costs for methane and carbon dioxide emissions, from the risk of climate tipping events and deterministic damages, are derived in an analytically tractable model. In the core model: social costs from tipping risks rise with income, just as they do for deterministic damages, and depend on only a few parameters. Consequently, methane’s weight (its social cost relative to carbon dioxide) is constant and independent of temperature projections. But other damage and tipping probability formulations assumed in the literature imply methane’s weight varies over time and with temperature projections.
Engineering biology (EngBio) is a dynamic field that uses gene editing, synthesis, assembly, and engineering to design new or modified biological systems. EngBio applications could make a significant contribution to achieving net zero greenhouse gas emissions. Yet, policy support will be needed if EngBio is to fulfil its climate mitigation potential. What form should such policies take, and what EngBio applications should they target? This paper reviews EngBio’s potential climate contributions to assist policymakers shape regulations and target resources and, in so doing, to facilitate democratic deliberation on desirable futures.
A three-sector – services, clean and dirty - integrated assessment model with endogenous technology is described. Optimal policy leads to a period of intense clean research and requires a carbon tax and clean research subsidies. Using multiple calibrations, I explore the relative performance of these instruments when acting alone, along with a clean production subsidy and a dirty research tax. A carbon tax wins in most, but if optimal policy occurs after 2050, each instrument wins in some calibrations. Both a carbon tax and a clean production subsidy should apply if research instruments are unavailable.
We discuss the prospects of recent promising methods of producing ammonia without fossil fuels. Despite demonstrating efficiency gains over previous similar approaches, the novel biological and electrochemical pathways require further large improvements to compete with electricity-powered Haber-Bosch. As some literature asserts that future production will shift to smaller scales, such as on-farm, we qualitatively discuss the economics of scale of future green ammonia production.
The framework used to endogenise technology growth by Acemoglu, Aghion, Bursztyn, and Hemous (2012) can exhibit increasing returns to research and hence multiple equilibria, including an unstable interior equilibrium. This paper discusses several selection methods of determining which equilibrium applies. Alternative methods can produce substantially different results when the elasticity of substitution between clean and dirty inputs is high.
Book Reviews
Other Papers
Some short run dynamics for CGE models. Presentation at the 18th Annual Conference on Global Economic Analysis 2015, Melbourne, Australia.
Wiskich A. (2013). Modelling electricity generation based on a competitive market in the GTAP model. Presented at the 16th Annual Conference on Global Economic Analysis, Shanghai, China.
Cao L., Wiskich T., Hodges C., McAndrew K. (2012). Comparing Policy Impacts of Different Household Demand Systems in a CGE Model. Presented at the 15th Annual Conference on Global Economic Analysis, Geneva, Switzerland.
Wiskich A., Fisher B., Matysek A., Newton P. (2011). Modelling Climate Change Impacts and Agriculture. Presented at the 14th Annual Conference on Global Economic Analysis, Venice, Italy.
Wiskich A. (2010). Computing game-theoretic equilibria in GTAP: Optimising regional climate change policies. Presented at the 13th Annual Conference on Global Economic Analysis, Penang, Malaysia.