Articles

Possibilities of Using Solar Photovoltaics and Electric Batteries in Agricultural Greenhouses in The Island of Crete, Greece

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Mitigation of the global environmental challenge of climate change requires the elimination of carbon emissions. Agricultural greenhouses are energy intensive production systems based mainly on fossil fuels. However, several renewable energy technologies are reliable and cost-effective and they could be used in them for heat and power generation. The possibility of using a solar photovoltaic and a battery storage system meeting the electricity demand in a grid-connected greenhouse in Crete, Greece which already uses locally produced solid biomass to cover the heat demand has been investigated. It has been estimated that the use of a solar photovoltaic system with nominal power 31.29 kWp  generating 48,500 kWh/year can meet the annual power demand in an existing greenhouse with covered surface 3,300 m2 in Crete. The cost of the solar photovoltaic system is estimated at 40,000 €. The capacity of Lithium-ion batteries for achieving one day power autonomy in the greenhouse has been estimated at 147.64 kWh while their cost is estimated at 63,333 €. The combined use of a solar photovoltaic system meeting the electricity demand and solid biomass meeting the heat demand results in a net-zero emissions greenhouse. Both renewable energy technologies are mature and economically attractive and they are currently used in Crete in many sectors. The current work indicates that decarbonization of agricultural greenhouses in Crete replacing the use of fossil fuels with renewable energies is feasible. The results of the present study could be used by all stakeholders of the greenhouse industry.

Decarbonization of the Cheese Making Industry on the Island of Crete, Greece

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Cheese making is a well-developed activity in the island of Crete, Greece since a long time ago. It is mainly based on local sheep’ and goats’ milk while the small-scale cheese making plants in Crete use conventional energy sources to meet their heat and electricity demand. However, solar energy and solid biomass are abundant in the island and they are currently used for heat and power generation. Elimination of carbon emissions in cheese making plants in Crete can be achieved with the replacement of grid electricity and fossil fuels used with local renewable energies such as solar energy and solid biomass. It has been estimated that complete elimination of the operational carbon emissions due to energy use in a small-size cheese making plant in Crete with annual capacity 120 tons cheese can be achieved with the installation of a solar photovoltaic system at 88 kWp for electricity generation and the annual use of 62.86 tons of olive kernel wood for heat production. Additionally, solar thermal systems and high efficiency heat pumps can be used for heat and cooling production. The abovementioned sustainable energy sources and technologies are mature, reliable, cost-efficient and they are currently used in Crete in various sectors. The results of the present study could be useful to all stakeholders of the cheese making industry in the island.

Carbon Emissions from Cruise Ships: A Case Study in The Ports of Souda and Heraklion, Crete, Greece

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Modern cruise ships consume considerable amounts of energy and emit large quantities of greenhouse gases during their luxury trips compared with other types of tourism. During the last years the ports of Souda and Heraklion, Crete host a large number of cruise vessels. The carbon emissions of cruise ships during their mooring in the abovementioned ports have been estimated using data from the existing literature. The alternative fuels which can be used in these cruise ships decreasing their emissions have been also examined. The carbon emissions from the mooring of cruise vessels in Souda port in 2024 have estimated at 16,505 tnCO2 while in Heraklion port at 30,537 tnCO2. Cruise ships face mounting pressure to reduce their environmental impact and alternative fuels are central to this transformation. Several alternative fuels including LNG, biofuels, hydrogen, ammonia, methanol, and electricity can be used in cruise ships substituting the fossil fuels currently used like heavy fuel oil. The ports of Souda and Heraklion should develop the necessary infrastructure to provide alternative fuels and on-shore electricity to cruise vessels approaching these ports in the near future. The current study could be useful to ports’ authorities in Crete, to cruising companies as well as to the stakeholders of Cretan ports.

Use of Sustainable Energy Sources and Technologies in Primary and Secondary School Buildings in Greece. Can They Eliminate their Carbon Footprint?

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School buildings consume energy covering their energy demand. The most of them utilize fossil fuels and grid electricity while the use of renewable energies is rather limited. School buildings should eliminate their carbon emissions in order to achieve the global target for net-zero carbon emissions by 2050. The energy consumption and the carbon emissions in schools have been evaluated. School buildings in Greece consume less than 100 kWh/m2 year. Solar thermal energy, solar photovoltaic energy and high efficiency heat pumps can cover all the energy demand in school buildings in Greece replacing the use of conventional energy sources. These energy technologies are reliable, mature and cost-effective. There are 7,756 primary and secondary school buildings in Greece consuming 1.67 TWh/year. The total cost of energy renovation eliminating their carbon emissions is estimated at 1,156,000 €/school or 8.96 billion € for the 7,756 schools in the country. For achieving the target of net-zero carbon emissions by 2050, 310 Greek schools should be energy refurbished every year eliminating their carbon footprint in the next 25 years. Taking into account the availability of benign energy sources and technologies the main barrier for eliminating the carbon emissions in school buildings in Greece by 2050 is the high investment cost. Our results could be useful for the development of the required policies for decarbonization in school buildings.