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Freeze Desalination-Membrane Distillation Hybrid Systems
Published in Kang-Jia Lu, Tai-Shung Chung, Membrane Distillation, 2019
Jian Chang, Kang-Jia Lu, Peng Wang, Tai-Shung Chung
While FD has many advantages over the conventional desalination processes, it is vulnerable to high feed concentrations (Wankat, 1973). By contrast, membrane distillation is able to treat feed concentrations that are a few times higher than the seawater concentration without much compromise on separation performance (Wang and Chung, 2015). According to the Raoult’s law, the vapor pressure only drops 3.6% when the seawater concentration is doubled. Given this benefit, MD is highly suitable for treating the concentrated brine from the FD step. A drawback of MD is its high energy demand. Nevertheless, it can be operated with the aid of renewable heat resources such as solar energy. It is a clean energy resource, and more importantly, it is able to generate electricity, a high-exergy energy carrier (Müller et al., 2011). Not only can it be used to heat up the feed solution but also power pumps and many other equipment. Additionally, using electricity will make it easier for the MD operators to control the heating duty. Although the direct solar water heating has a higher efficiency than photovoltaic efficiency, it has a drawback by fluctuating the feed with random temperatures (Qtaishat and Banat, 2013; Wang et al., 2017). Another means to generate electricity is to harvest energy from the LNG regasification process. In the study conducted by Dorosz et al., it was found that a direct expansion-organic Rankine cycle hybrid system (DE-ORC) reached the highest exergetic efficiency of 36%, that is, 380 kJ/kg (Dorosz et al., 2018).
Resources
Published in Frank Jackson, Dilwyn Jenkins, Renewable Energy Systems, 2013
In the UK, there are what is known as Renewable Heat Incentives which provide small grants towards solar thermal systems and a generation tariff which pays a sum for every kilowatt hour of heat energy produced. The following link provides more information about this: www.decc.gov.uk/en/content/cms/meeting_energy/Renewable_ener/incentive/incentive.aspx
Geothermal energy
Published in Volker Quaschning, Understanding Renewable Energy Systems, 2016
One benefit of adsorption heat pumps is that no toxic materials are used. The heat needed in the process can come from renewable heat, such as solar thermal, geothermal, or biogas. Most commercial systems, however, currently still run on natural gas.
Energy utilisation in a combined geothermal and organic Rankine power cycles
Published in International Journal of Sustainable Energy, 2019
Yousef S. H. Najjar, Ala’ E. Qatramez
An increase of about 1.8 GW of electricity from geothermal plants in the five years 2010–2015 has been achieved following the rough standard linear trend of approximately 350 MW/year (Bertani 2016). Geothermal is considered as renewable heat source which comes from beneath the earth surface. Geothermal heat source varies in temperature from 50 to 350°C and either can be dry, mainly steam, a mixture of steam and water or just water. The temperature of the resource is a major determinant of the type of technology required to extract the heat and the uses it can be applied (Hettiarachchi 2007; Barbier 1997; Barbie 2002).