Liam Wagner

Future prospects of microalgal biofuel production systems.

Climate change mitigation, economic growth and stability, and the ongoing depletion of oil reserves are all major drivers for the development of economically rational, renewable energy technology platforms. Microalgae have re-emerged as a popular feedstock for the production of biofuels and other more valuable products. Even though integrated microalgal production systems have some clear advantages and present a promising alternative to highly controversial first generation biofuel systems, the associated hype has often exceeded the boundaries of reality. With a growing number of recent analyses demonstrating that despite the hype, these systems are conceptually sound and potentially sustainable given the available inputs, we review the research areas that are key to attaining economic reality and the future development of the industry.

Trading Off Global Fuel Supply, CO2 Emissions and Sustainable Development.

The United Nations Conference on Climate Change (Paris 2015) reached an international agreement to keep the rise in global average temperature ‘well below 2°C’ and to ‘aim to limit the increase to 1.5°C’. These reductions will have to be made in the face of rising global energy demand. Here a thoroughly validated dynamic econometric model (Eq 1) is used to forecast global energy demand growth (International Energy Agency and BP), which is driven by an increase of the global population (UN), energy use per person and real GDP (World Bank and Maddison). Even relatively conservative assumptions put a severe upward pressure on forecast global energy demand and highlight three areas of concern. First, is the potential for an exponential increase of fossil fuel consumption, if renewable energy systems are not rapidly scaled up. Second, implementation of internationally mandated CO2 emission controls are forecast to place serious constraints on fossil fuel use from ~2030 onward, raising energy security implications. Third is the challenge of maintaining the international ‘pro-growth’ strategy being used to meet poverty alleviation targets, while reducing CO2 emissions. Our findings place global economists and environmentalists on the same side as they indicate that the scale up of CO2 neutral renewable energy systems is not only important to protect against climate change, but to enhance global energy security by reducing our dependence of fossil fuels and to provide a sustainable basis for economic development and poverty alleviation. Very hard choices will have to be made to achieve ‘sustainable development’ goals.

Catastrophe Management and Inter-Reserve Distance for Marine Reserve Networks

We consider the optimal spacing between marine reserves for maximising the viability of a species occupying a reserve network. The closer the networks are placed together, the higher the probability of colonisation of an empty reserve by an occupied reserve, thus increasing population viability. However, the closer the networks are placed together, the higher the probability that a catastrophe will cause extinction of the species in both reserves, thus decreasing population viability. Using a simple discrete-time Markov chain model for the presence or absence of the species in each reserve we determine the distance between the two reserves which provides the optimal trade-off between these processes, resulting in maximum viability of the species.

Modeling the deployment of plug-in hybrid and electric vehicles and their effects on the Australian National Electricity Market

The development of hybrid and fully electric vehicles could deliver significant reductions of emissions from the Australian transportation sector by shifting its major energy source from internal combustion to electricity. This shift towards the the use of electricity shifts the point source emissions to one which has a lower emissions intensity. Changes in load behaviour as a result of the consumer uptake of these vehicles will have significant consequences for network and central planners for the future of Australias electricity supply industry. This paper investigates the effects on the security of supply of energy during these previously unseen demand patterns, while also examining changes to spot market prices and changes in emissions rates. The simulation results indicate that wholesale prices during the off-peak period will increase slowly over time with controlled charging. While uncontrolled charging increases the incidence of extreme price events and a considerable number of hours with un-served energy within the network. This increase in spot prices will require further review by policy makers of regulated retail electricity tariffs. We also discuss the implementation of possible changes to the retail tariff structure to accommodate the charging of these vehicles.

Using simulated annealing to calculate the trembles of trembling hand perfection

Within the literature on noncooperative game theory, there have been a number of algorithms which will compute Nash equilibria. We show that the family of algorithms known as Markov chain Monte Carlo (MCMC) can be used to calculate Nash equilibria. MCMC is a type of Monte Carlo simulation that relies on Markov chains to ensure its regularity conditions. MCMC has been widely used throughout the statistics and optimization literature, where variants of this algorithm are known as simulated annealing. We show that there is interesting connection between the trembles that underlie the functioning of this algorithm and the type of Nash refinement known as trembling hand perfection. We show that it is possible to use simulated annealing to compute this refinement.

Finding traitors in secure networks using Byzantine agreements

Secure networks rely upon players to maintain security and reliability. However not every player can be assumed to have total loyalty and one must use methods to uncover traitors in such networks. We use the original concept of the Byzantine Generals Problem by Lamport [8], and the more formal Byzantine Agreement describe by Linial [10], to find traitors in secure networks. By applying general fault-tolerance methods to develop a more formal design of secure networks we are able to uncover traitors amongst a group of players. We also propose methods to integrate this system with insecure channels. This new resiliency can be applied to broadcast and peer-to-peer secure com- munication systems where agents may be traitors or be- come unreliable due to faults.