A simulation study of the use of electric vehicles as storage on the New Zealand electricity grid

This paper describes a simulation to establish the extent to which reliance on non-dispatchable energy sources, most typically wind generation, could in the future be extended beyond received norms, by utilizing the distributed battery capacity of an electric vehicle fleet. The notion of exploiting the distributed battery capacity of a nation’s electric vehicle fleet as grid storage is not new. However, this simulation study specifically examines the potential impact of this idea in the New Zealand context. The simulation makes use of real and projected data in relation to vehicle usage, full potential non-dispatchable generation capacity and availability, taking into account weather variation, and typical daily and seasonal patterns of usage. It differs from previous studies in that it is based on individual vehicles, rather than a bulk battery model. At this stage the analysis is aggregated, and does not take into account local or regional flows. A more detailed analysis of these localized effects will follow in subsequent stages of the simulation

Power and energy visualization for the micro-management of household electricity consumption

The paper describes a pilot system for the detailed management of domestic electricity consumption aimed at minimizing demand peaks and consumer cost. Management decisions are made both interactively by consumers themselves, and where practical, automatically by computer. These decisions are based on realtime pricing and availability information, as well as current and historic usage data. The benefits of the energy strategies implied by such a system are elaborated, showing the potential for significant peak demand reduction and slowing of the need for growth in generation capacity. An overview is provided of the component technologies and interaction methods we have designed, but the paper focuses on the communication of real-time information to the consumer through a combination of specific and ambient visualizations. There is a need for both overview information (eg how much power is being used right now; how much energy have we used so far today; what does it cost?) and information at the point-of-use (is it OK to turn this dryer on now, or should I wait until later?). To assist the design of these visualizations, a survey is underway aimed at establishing people's understanding of power and energy concepts

Smart energy interfaces for electric vehicles

Electric vehicle charging strategies rely on knowledge of future vehicle usage, or implicitly make assumptions about a vehicle’s usage. For example, a na¨ıve charging strategy may assume that a full charge is required as soon as possible and simply charge at the maximum rate when plugged in, whereas a smart strategy might make use of the knowledge that the vehicle is not needed for a number of hours and optimise its charging behaviour to minimise its impact on the electricity grid. These charging strategies may also offer vehicle-to-grid services. To achieve this functionality, a driver needs to specify the details of the next trip—or sequence of trips—in order for the charging strategy to perform optimally. This paper explores the value of next-trip information, and presents a potential user interface to assist a driver with providing these details

Smart charging strategies for Electric Vehicles utilising non-dispatchable renewable electricity generation

Access to an inexpensive and reliable supply of energy is critical for the success of modern civilisation. Since the beginning of the Industrial Revolution in the mid 18th century, fossil fuels have enabled great advances across many aspects of society, which have increased the standard of living for many. Unfortunately, dwindling supplies and greenhouse gas emissions resulting from their use means that the continued utilisation of these fuels - particularly for electricity generation and transportation - is simply not sustainable. Present-day electricity systems are built around the premise that generation is flexible and controllable, while load - generally speaking - is not. This leads to dispatch models where generation is scheduled to meet load, plus some additional capacity to accommodate forecast errors and potential equipment failure. Many renewable generation technologies, such as wind and solar photovoltaics, are non-dispatchable and cannot be scheduled to produce electricity on-demand. Successfully utilising these energy sources therefore requires flexibility in other parts of the system. Electric Vehicles (EVs) produce no tailpipe emissions, and can be charged at any location with an electricity supply; at home, work, supermarket, or dedicated charging facilities. Because driving times tend to coincide with existing peak electricity demand, EV charging will occur at times of already high electricity demand if not controlled. Fortunately, there is substantial flexibility over the timing of charging, which can be exploited to minimise adverse impacts on electricity grids. Additional benefits are realised when energy is allowed to flow from the vehicle's battery back into the electricity grid; a concept known as vehicle-to-grid (V2G). Through the development of a simulation based on future energy scenarios in New Zealand, the research presented in this thesis evaluates the extent to which the flexibility of EV charging may be exploited to support high levels of non-dispatchable renewable electricity generation. Several EV charging strategies are introduced and evaluated across a range of metrics with wind penetration levels ranging between 10% and 50% on an annual energy basis. With a V2G-enabled fleet consisting of one million vehicles (25% of New Zealand's projected light vehicle fleet size in 2030), it is found that EV charging is sufficiently flexible to the extent that electricity generation does not need to follow daily variations in load. The EV fleet is capable of meeting the power and ramping requirements of the electricity grid, in addition to its own transportation needs, so long as sufficient energy is generated within a few days of its consumption. Such flexibility is expected to greatly assist the future expansion of non-dispatchable renewable electricity generation in New Zealand

Improved grid integration of intermittent electricity generation using electric vehicles for storage: A simulation study

This paper describes a simulation to establish the extent to which reliance on non-dispatchable energy sources, particularly wind generation, could in the future be extended beyond accepted norms, by utilizing the distributed battery capacity of an electric vehicle fleet for storage. The notion of exploiting the distributed battery capacity of an electric vehicle fleet as grid storage is not new. However, this simulation study specifically examines the potential impact of the idea in the New Zealand context. The simulation makes use of real and projected data in relation to vehicle usage, full potential wind generation capacity and availability, taking into account weather variation, and typical daily and seasonal patterns of electricity usage. It differs from previous studies in that it is based on individual vehicles, rather than a bulk battery model. At this stage, the simulation does not take into account local or regional flows. A more detailed analysis of these localized effects will follow in subsequent stages of the simulation work

Visualising present and past: a meter with a flexible pointer

Meters and gauges based on analogue pointers provide a convenient way to visualise single dimensional data streams, such as speed, voltage, altitude, or fuel level. However, often a small amount of historical information helps to understand the data at a glance, and reduces the need for constant vigilance; is the parameter relatively stable; is it increasing or decreasing? Have there been any transients in the past minute? What trends are present? This paper describes a virtual analogue meter with a flexible pointer that shows both the instantaneous value at the tip and bends to a brief interval of history along its length. The meter has been developed in the context of monitoring the electricity grid, but has many other potential applications

Effect of Ca2+ ions on the adhesion and mechanical properties of adsorbed layers of human Osteopontin

Using an atomic force microscope and a surface force apparatus, we measured the surface coverage, adhesion, and mechanical properties of layers of osteopontin (OPN), a phosphoprotein of the human bones, adsorbed on mica. OPN is believed to connect mineralized collagen fibrils of the bone in a matrix that dissipates energy, reducing the risk of fractures. Atomic force microscopy normal force measurements showed large adhesion and energy dissipation upon retraction of the tip, which were due to the breaking of the many OPN-OPN and OPN-mica bonds formed during tip-sample contact. The dissipated energy increased in the presence of Ca2+ ions due to the formation of additional OPN-OPN and OPN-mica salt bridges between negative charges. The forces measured by surface force apparatus between two macroscopic mica surfaces were mainly repulsive and became hysteretic only in the presence of Ca2+: adsorbed layers underwent an irreversible compaction during compression due to the formation of long-lived calcium salt bridges. This provides an energy storage mechanism, which is complementary to energy dissipation and may be equally relevant to bone recovery after yield. The prevalence of one mechanism or the other appears to depend on the confinement geometry, adsorption protocol, and loading-unloading rates