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Pulsed electrical discharges in a gas–liquid mixture deposit energy into both phases. Here, we propose a model to simulate breakdown in multiphase based on experimental data. Furthermore, we estimated breakdown voltage in each phase and then estimated energy deposition in each phase. Discharge in pure liquid showed a highly stochastic nature, having a wide breakdown voltage distribution, while the mean value closely follows a one term power law as a function of gap spacing. When there is external gas injection to the gap, breakdown voltage increased significantly due to charge dissipation on bubble surface. This effect was simulated to predict breakdown voltage in liquid with gas injection at different rates. A multiphase system model was developed to simulate breakdown in the gas–liquid phase. The model is a superposition of power law and Meek criteria physical models for the liquid and gas phases, respectively, with empirically derived coefficients. Energy deposition into each phase was estimated by this model. The gap spacing is the primary factor determining breakdown voltage and energy distribution. In studied conditions, we were able to predict the breakdown voltage and estimate energy deposition into different phases. When the gap and flow rate vary between 2 and 10 mm and flow rate 0–1 LPM, 50%–93% of electrical energy is deposited into the liquid. This model allows for predicting breakdown voltage in a multiphase. Furthermore, it allows for control of the energy distribution among the phases in a multiphase pulsed discharge system.

Electrical discharges in liquids with and without gas injection was experimentally studied with two circuits (RC and single spark gap). Electrical breakdown could be initiated from the following mechanisms: electrode initiation; impurity initiation; and Taylor cone driven initiation. Discharges initiated by electrodes were observed only with the single spark gap circuit. Impurities and Taylor cones can initiate discharges when using the RC circuit. With the single spark gap circuit, bubbles were nearly stationary in the gap before and during discharges because of the limited time to respond to the electric field growth (dV/dt = 1 kV ns −1 ). Bubbles and impurities gain significant energy and undergo significant dynamic changes with the RC circuit under a long rising time. Charge relaxation time on bubbles or impurities in the fluids were close to 100 ms, which is comparable with the circuit rising time. Bubble dynamics observed include reduced bubble size, increased bubble speed and shape change. Taylor cones were observed on bubble surface using a high-speed camera during multiple discharge events, and usually led to breakdown. Taylor cones develop on a bubble surface through multiple states over a period of 10-500 μs. State one was typically seen on a bubble surface with a sharp tip caused by the residual charge. A single streamer was initiated on the tip of the cone at state two. State three developed multiple bush-like streamers on the cone and usually triggered a breakdown in the gap. Discharge behaviors in liquids were also investigated with the RC circuit at different pulsing frequencies. At a low pulsing frequency (1 Hz), discharge events are independent from each other. When pulsed above 10 Hz, bubbles created in the gap accumulate and participate in the next discharge event. Bubble accumulation results in a cloud where local secondary discharges are observed with a much higher frequency up to a few kHz for several milliseconds.

Global GHG (greenhouse gas) emissions are increasing substantially and electricity sector is one of the key contributors to the world’s total GHG emissions. GHG emissions cause ozone layer depletion and global warming. Different policy regulation agencies are adopting regulations to reduce GHG emissions in various sectors. People already have started power generation from cleaner sources. Renewable energy sources can provide cleaner electricity. Bangladesh is a densely populated country and most of the country’s electricity is produced from natural gas and coal. The Bangladesh government has set a goal to utilize renewable energy for the production of 10% of its electricity by the year 2020. Bangladesh has a lot of isolated coastal areas which are not connected to the national grid which can be electrified by using abundant wind energy. In this study a techno-economic analysis has been conducted for an off-grid island of Bangladesh. The analysis was conducted by developing a data intensive model that calculates the generation cost of electricity from wind energy. The model also estimates the capital cost of the system. The model shows that electricity can be produced from wind energy at a cost of $0.57/kWh. The system’s capital cost was calculated to be $63,550.16.Article History: Received October 15th 2016; Received in revised form January 26th 2017; Accepted February 4th 2017; Available onlineHow to Cite This Article: Rahman, M.M., Baky, M.A.H, and Islam, A.K.M.S. (2017) Electricity from Wind for Off-Grid Applications in Bangladesh: A Techno-Economic Assessment. International Journal of Renewable Energy Develeopment, 6(1), 55-64.http://dx.doi.org/10.14710/ijred.6.1.55-64

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