Current Affairs: Powering NZ’s tomorrow - The MHD Way

Here is Purav’s description of his project.

My project investigated magnetohydrodynamics (MHD) as a possible alternative for generating additional geothermal energy. New Zealand already generates a significant amount of energy from geothermal energy, where hot, fast-moving fluids move through geothermal systems. This made me wonder if New Zealand can recover additional electricity directly from these moving fluids.

MHD occurs when an electrically conductive fluid moves through a magnetic field. The ions within the fluid experience the Lorentz force and interact with the magnetic field, causing charge separation and producing a voltage across electrodes. 

I designed and built a small-scale MHD generator using neodymium magnets, stainless-steel electrodes and a circulating fluid tank. After evaluating my original prototype, I redesigned the system to improve the magnetic-field arrangement and electrode configuration, using Finite Element Magnetics Method (FEMM) computer simulation to help simulate the magnetic field.

My investigation tested different electrolytes across multiple concentrations, while also examining the effects of temperature, operating time and flow conditions. I designed three different funnel geometries to investigate how changing the fluid-flow conditions affected voltage generation.

My results showed that measurable voltage could be produced and that the electrical response depended on a combination of electrolyte composition, concentration and flow conditions, rather than one factor alone. The project suggests that MHD could be investigated further as a complementary energy-recovery technology, potentially recovering additional electrical energy from conductive fluids already flowing through New Zealand's geothermal infrastructure and helping improve its renewable energy systems overall.

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