Exergetic analysis of hybrid power plants with biomass and photovoltaics coupled with a solid-oxide electrolysis system

Journal of Cleaner Production

Robinson

Loizidou

2016

Self Cite

The ambitious vision of off-grid renewable energy autonomy of remote regions has yet to come to fruition. The development of comprehensive energy production systems would be needed to achieve such a goal. This study consists of the simulation and exergetic evaluation of a novel hybrid power plant for stand-alone operation aiming to provide electricity autonomy of a Mediterranean island. The considered power plant is simulated dynamically over an annual cycle and accounts for both energy input fluctuations and electricity surplus. The plant combines a photovoltaic array with wind turbines for energy input, coupled with electricity storage and a hydrogen generation facility for stable output. Unlike other similar studies, the energy system presented here relies on real-case weather and demand data of a relatively large remote community and is optimized to ensure continuous operationeven under extreme conditions. It is seen that this stand-alone hybrid power plant constitutes a robust and secure alternative to the current conventional energy situation; the combined renewable technologies succeed in complementing each other and offer stable performance throughout the year 1 without the requirement of additional support by fossil fuels. The mean annual exergetic efficiency of the plant is found to be 17.9 %, producing approximately 25,000 MWh of electricity per year, along with a secondary product (hydrogen) produced in the electrolyzer of the plant. Although this additional product is associated with additional investment cost, it offers the possibility to stabilize the power plant's performance and can be used as an additional source of financial input to the community.

Section: Figurementioning

confidence: 99%

Exergetic analysis and dynamic simulation of a solar-wind power plant with electricity storage and hydrogen generation

Journal of Cleaner Production

Robinson

Loizidou

2016

Self Cite

“…This suggestion is similar to a proposal presented by the municipality of Skyros for the combination of a pumped-storage hydropower plant with wind turbines to store and generate energy. The case presented here includes solar energy and it is designed and optimized for stand [29,30]. The electrolyzer uses electricity to convert any electricity surplus into hydrogen through water electrolysis.…”

Section: Simulation Of the Power Plantmentioning

confidence: 99%

Simulation and analysis of a stand-alone solar-wind and pumped-storage hydropower plant

Robinson

Loizidou

2016

Energy

Self Cite

This work presents the simulation and evaluation of a renewable hybrid power plant for off-grid fully autonomous operation on an intermediate-sized island in the Aegean Sea. For the first time, a stand-alone energy system including storage facilities is simulated, optimized and analyzed relying on real-case weather and demand data of a relatively large remote community. Optimization of the power plant structure shows that to ensure continuous off-grid energy generation, even under extreme conditions, the combination of more than one renewable technology is required. The hybrid power plant consists of a pumped-storage hydropower plant, photovoltaic cells and wind turbines. Energy surplus of the power plant is used in the incorporated electrolyzer to generate a secondary product, hydrogen. Robust operation of the plant results in 48 % of the energy generated stemming from the photovoltaic system and 52 % from the wind turbines. The pumped-storage hydropower plant has a mean annual power output of 1.0 MW. The total mean annual efficiency of the hybrid plant is found to be 14.4 %.Although stand-alone operation was achieved with the proposed plant, this requirement led to net energy output restrictions, capacity oversizing and large storage facilities.

“…Any electricity residual after covering the energy demand and charging the electricity storage system is lead to the electrolyzer coupled to the plant. The electrolyzer, an intermediate-temperature solid-oxide electrolysis cell [50], uses electricity to generate hydrogen through water electrolysis. The electrolysis cells work at thermoneutral voltage, at a temperature of 700 °C, with a steam conversion rate in the cathode chamber of 61 % and a molar ratio between the anode and cathode of 1:1.…”

Section: Figurementioning

confidence: 99%

On the economics of stand-alone renewable hybrid power plants in remote regions

Energy Conversion and Management

2016

Self Cite

In recent years ever more examples of regions that have managed to achieve or orientate themselves towards renewable energy sufficiency are emerging. However, actions to create energy autonomy are mainly the result of isolated activities and they are less driven from fully organized movements. In addition, total energy independence without the support of a centralized electrical grid is yet to be achieved. The objectives of this work are to investigate the associated costs of stand-alone renewable hybrid power plants and compare them to the cost of fossil-fuel-based conventional plants. The plants examined here are designed to fully cover the electricity needs of an island.Islands are remote areas with relatively isolated communities that may face numerous energy problems and rely heavily on foreign and environmentally-harmful fuels. It is shown that the relatively high cost of electricity of a remote region can increase the competitiveness and promote the wider incorporation of technologies based on renewable energy sources that may, in other cases, seem economically inferior to business-as-usual energy solutions.