Veröffentlichungen

@conference{Geyer2018,
title = {Use Cases with Economics and Simulation for Thermo-Chemical District Networks},
author = {Philipp Geyer and Muhannad Delwati and Martin Buchholz and Alessandro Giampieri and Andrew Smallbone and Anthony P Roskilly and Reiner Buchholz and Mathieu Provost},
url = {https://doi.org/10.3390/su10030599},
doi = {10.3390/su10030599},
year = {2018},
date = {2018-01-01},
journal = {Sustanability},
volume = {10},
number = {3},
pages = {1-33},
publisher = {MDPI AG},
abstract = {Thermo-chemical networks using absorption and desorption to capture and valorise the potential of very low-grade residual heat (20 °C to 60 °C) to offer a reduction of end user costs and increased primary energy efficiency. The paper demonstrates the technical and economic potential of thermo-chemical networks by defining use cases and their related level of energy efficiency and technological feasibility. Furthermore, specific economic scenarios, including estimations on investment and operation costs, demonstrate the economic benefit of the technology. Simple payback periods between about 0.5 and 7.5 years indicate a good economic feasibility with end user costs below 4 €ct/kWh-equivalent and refunds of 0.5 to 1 €ct/kWh for the required residual heat. Due to the low-temperature characteristics of the relevant systems and services, detailed simulations are required to approve the functioning and viability of the new technology. For this purpose, the paper demonstrates the simulation outline using the example of space heating based on a low-temperature air heating system partially driven with thermo-chemical fuel.},
note = {Thermo-chemical networks using absorption and desorption to capture and valorise the potential of very low-grade residual heat (20 textdegreeC to 60 textdegreeC) to offer a reduction of end user costs and increased primary energy efficiency. The paper demonstrates the technical and economic potential of thermo-chemical networks by defining use cases and their related level of energy efficiency and technological feasibility. Furthermore, specific economic scenarios, including estimations on investment and operation costs, demonstrate the economic benefit of the technology. Simple payback periods between about 0.5 and 7.5 years indicate a good economic feasibility with end user costs below 4 texteuroct/kWh-equivalent and refunds of 0.5 to 1 texteuroct/kWh for the required residual heat. Due to the low-temperature characteristics of the relevant systems and services, detailed simulations are required to approve the functioning and viability of the new technology. For this purpose, the paper demonstrates the simulation outline using the example of space heating based on a low-temperature air heating system partially driven with thermo-chemical fuel.},
keywords = {absorption processes, industrial drying, space heating and cooling, thermo-chemical district energy networks},
pubstate = {published},
tppubtype = {conference}
}

@article{Geyer2017,
title = {Hybrid thermo-chemical district networks – Principles and technology},
author = {Philipp Geyer and Martin Buchholz and Reiner Buchholz and Mathieu Provost},
url = {http://www.sciencedirect.com/science/article/pii/S0306261916309394},
doi = {https://doi.org/10.1016/j.apenergy.2016.06.152},
issn = {0306-2619},
year = {2017},
date = {2017-01-01},
journal = {Applied Energy},
volume = {186},
pages = {480 - 491},
note = {Sustainable Thermal Energy Management (SusTEM2015)},
keywords = {Cooling and drying, District networks for heating, Open thermo-chemical sorption technology, Residual heat usage, Solar thermal energy, Systems engineering},
pubstate = {published},
tppubtype = {article}
}

@proceedings{Decorme2017,
title = {Reducing Energy Consumption and Carbon Footprint by Smart and Sustainable Use},
author = {Régis Decorme and Tracey Crosbie and Vladimir Vukovic and Mia Ala-Juusela and Martin Klepal and Malcolm Yadack and Martin Buchholz and Andrea Costa},
url = {http://doi.org/10.3390/proceedings1071101},
doi = {10.3390/proceedings1071101},
year = {2017},
date = {2017-01-01},
volume = {1},
abstract = {The workshop “Reducing energy consumption and carbon footprint by smart and sustainable
use” was organized on 29 June 2017 in the context of the International conference Sustainable Places
2017 with the aim to discuss the latest progress and innovations resulting from 7 projects developing
solutions to reduce energy consumption and carbon footprint by smart and sustainable use.

Reducing Energy Consumption and Carbon Footprint by Smart and Sustainable Use (PDF Free Download). Available from: https://www.researchgate.net/publication/321735138_Reducing_Energy_Consumption_and_Carbon_Footprint_by_Smart_and_Sustainable_Use [accessed May 30 2018].},
keywords = {block of buildings, demand response, district heating and cooling, energy efficient buildings, energy monitoring, energy storage, smart grids},
pubstate = {published},
tppubtype = {proceedings}
}

@conference{Geyer2015,
title = {Design and Modelling of a Hybrid Thermal and Thermochemical Network Technology},
author = {Philipp Geyer and Martin Buchholz and Reiner Buchholz and Mattieu Provost},
url = {https://lirias.kuleuven.be/handle/123456789/468472},
year = {2015},
date = {2015-01-01},
series = {SusTEM2015},
note = {no isbn ; status: published},
keywords = {thermo-chemical network},
pubstate = {published},
tppubtype = {conference}
}

@article{MohamedH.Nour2015,
title = {Greenhouse based desalination for brackish water management using bittern evaporative cooling technique},
author = {Martin Buchholz and Mohamed H. Nour and Ashraf Ghanem and Ahmed Nassar},
url = {http://doi.org/10.2166/ws.2015.025},
doi = {10.2166/ws.2015.025},
year = {2015},
date = {2015-01-01},
journal = {Water Science and Technology: Water Supply},
abstract = {The Arab region is characterized by arid and semi-arid conditions with very limited renewable water resources. Most of the surface water comes from transboundary streams and most of the groundwater resources are fossil in nature. Water quality degradation and excessive use of pesticides and herbicides in agriculture pose severe environmental and health risks. The underlying research is a joint effort between Cairo University and the Technical University of Berlin to develop technologies and strategies for sustainable pesticide-free agriculture using saline or brackish water. This project builds on a previously implemented project in Spain by the German research partner that introduced the concept of Watergy, which presents an integrated desalination horticulture solar greenhouse. In this current research, the Watergy greenhouse is further developed to meet more arid climate requirements, reduce construction costs, and increase resource utilization efficiency. Several lab-scale experiments and a 100 m2 prototype were built in Egypt to optimize the process and answer research questions. Lessons learned from this project provided guidelines on the development of the most efficient approach of desalination and water management in the system, devised a cost-effective and efficient heat exchanger using low-cost local material, and established the feasibility of the system in the arid climate together with prospects for wider applications. The proposed greenhouse was estimated to be able to save in irrigation water 40% for cherry tomatoes and cucumbers, and 50% for bell peppers. Maximum crop yield can be achieved at extended upper salinity levels using the proposed greenhouse as follows: from 1,000 to 1,700 mg/L for cherry tomatoes; from 960 to 2,000 mg/L for bell peppers; and from 1,600 to 2,700 mg/L for cucumbers.},
keywords = {Arab region, desalination, semi-arid conditions, solar greenhouse, water resources},
pubstate = {published},
tppubtype = {article}
}

@inproceedings{Balas2014,
title = {Expert Control for the Coupled Tanks Greenhouse},
author = {Marius Mircea Balas and Martin Buchholz and Sanda V Balas},
url = {https://doi.org/10.1007/978-3-319-18416-6_74},
doi = {10.1007/978-3-319-18416-6_74},
year = {2014},
date = {2014-01-01},
booktitle = {Soft Computing Applications - Proceedings of the 6th International Workshop Soft Computing Applications, SOFA 2014, Volume 2, Timisoara, Romania, 24-26 July 2014},
pages = {939--947},
crossref = {DBLP:conf/sofa/2014-2},
keywords = {greenhouse cooling},
pubstate = {published},
tppubtype = {inproceedings}
}

@conference{MohamedH.Nour2014,
title = {Greenhouse Based Desalination for Sustainable Agriculture in Desert Climate},
author = {Ashraf Ghanem and M Mohamed H. Nour and Martin Buchholz and Ahmed Fayez Nassar},
url = {https://www.researchgate.net/publication/262269354_Greenhouse_Based_Desalination_for_Sustainable_Agriculture_in_Desert_Climate},
year = {2014},
date = {2014-01-01},
series = {International IWA Conference on Desalination, Environment and Marine Outfall System},
abstract = {The Arab Region is characterized by arid and semi-arid conditions with very limited renewable water resources. Most of the surface water comes from transboundary streams and most of the groundwater resources are fossil in nature. Water quality degradation and excessive use of pesticides and herbicides in agriculture pose severe environmental and health risks. The underlying research is a joint effort between Cairo University and the Technical University of Berlin to develop technologies and strategies for sustainable pesticide free agriculture using saline or brackish water. This project builds on a previously implemented project in Spain by the German research partner that introduced the concept of Watergy, which presents an integrated desalination horticulture solar greenhouse. In this current research the Watergy greenhouse is further developed to meet more arid climate requirements, reduce construction costs, and increase resource utilization efficiency. Several lab scale experiments and a 100 m2 prototype were built in Egypt to optimize the process and answer research questions. Lessons learned from this project provided guidelines on the development of the most efficient approach of desalination and water management in the system, devised a cost effective and efficient heat exchanger using low-cost local material, and established the feasibility of the system in the arid climate together with prospects for wider applications. The proposed system provides the opportunity for over 40%-50% reduction in water consumption and significant enhancement in crop yields at much higher salinity levels.

Greenhouse Based Desalination for... (PDF Download Available). Available from: https://www.researchgate.net/publication/262269354_Greenhouse_Based_Desalination_for_Sustainable_Agriculture_in_Desert_Climate [accessed May 30 2018].},
keywords = {closed greenhouse, desalination, pesticide free cultivation, watergy},
pubstate = {published},
tppubtype = {conference}
}

@conference{Karasu2013a,
title = {Regional Thermal Energy Network Based on Waste Energy with Desiccants: Pilot Project within a Climate Envelope},
author = {Arda Karasu and Martin Buchholz and Reiner Buchholz},
url = {https://www.researchgate.net/publication/262258183_Regional_Thermal_Energy_Network_Based_on_Waste_Energy_with_Desiccants_Pilot_Project_within_a_Climate_Envelope},
year = {2013},
date = {2013-01-01},
abstract = {A significant contribution to climate change adaptation can be achieved through using regional resources, which are not assessed till now; for instance through storage and using local waste energy by means of desiccants. Therefore, it is planned to build a new thermal energy network in a developing region in Berlin. The basic principle is using the waste heat through reduction of water content within liquid desiccants. The emerging hygroscopic potential can be transported, stored and coupled to the latent heat fluxes in air. Following, it can be again regenerated through waste heat resources in the region, thus closing the cycle. A small scale test- and demonstration unitwill be run in a prototype, so called “climate envelope”, which enables desiccant based acclimatization through solar gains and plants as heat and humidity source. Climate envelope concept bases on a transparent envelope covering the whole building and has three functions, being (1) enhancing the energy efficiency through passive use of solar energy, (2) protection from noise and air pollutants in traffic corridors and (3) additional living spaces. The prototype will be built up in the southern part of Berlin, in order to demonstrate the main technological components of climate envelopes and waste energy usage through desiccants, especially showing the perspective of using vegetation as a means of humid air production in a solar collector system and as a filter element of air and water. The demonstration prototype will be used as an essential element for demonstrating, evaluating, and facilitating innovative and integrated low-carbon interventions in order to stimulate economic development while lowering carbon footprint through sustainable energy consumption. It will mitigate the impact of climate change and drive forward knowledge on how to create sustainable EU Cities through a systemic neighborhood approach.

Regional Thermal Energy Network Based on... (PDF Download Available). Available from: https://www.researchgate.net/publication/262258183_Regional_Thermal_Energy_Network_Based_on_Waste_Energy_with_Desiccants_Pilot_Project_within_a_Climate_Envelope [accessed May 30 2018].},
keywords = {climate envelop, closed greenhouse, desiccant, thermo-chemical network, waste energy},
pubstate = {published},
tppubtype = {conference}
}

@book{Karasu2013b,
title = {Bauen mit Klimahüllen},
author = {Arda Karasu and Martin Buchholz},
url = {https://www.researchgate.net/publication/308965330_Bauen_mit_Klimahullen},
doi = {10.14279/depositonce-3851},
isbn = {978-3798326484},
year = {2013},
date = {2013-01-01},
publisher = {Universitätsverlag der TU Berlin},
abstract = {Würden Sie ein Fenster trotz chaotischer Bedingungen außerhalb des Gebäudes wirklich gerne öffnen? Exzessiver Lärm, schlechte Wetterbedingungen, dreckige bis stinkende Luft, unbefriedigende optische Eindrück... Nicht überall, wo unter angenehmen klimatischen Bedingungen die Fenster geöffnet werden könnten, ist es empfehlenswert dies auch zu tun. Eine Klimahülle ist zwar kein Wundermittel, mit der sich immer eine schöne Aussicht oder ein optimales Wunschklima erschaffen lässt, jedoch bietet sie Schutz gegen extreme Klimabedingungen und Lärm in der Umgebung und schafft, unter der Voraussetzung einer entsprechenden architektonischen Gestaltung, eine angenehme Oase der Ruhe und der frischen Luft.

Bauen mit Klimahüllen (PDF Download Available). Available from: https://www.researchgate.net/publication/308965330_Bauen_mit_Klimahullen [accessed May 29 2018].},
keywords = {Bauen, Klimahülle},
pubstate = {published},
tppubtype = {book}
}

@conference{Buchholz2012a,
title = {Nutzung von Sole als Energieträger und Speichermedium in einem urbanen Entwicklungsgebiet},
author = {Martin Buchholz and Reiner Buchholz and Anja Hanßke and Christopher Paitazoglou and Felix Ziegler},
url = {http://doi.org/10.13140/2.1.4682.1763},
doi = {10.13140/2.1.4682.1763},
year = {2012},
date = {2012-01-01},
series = {3rd International Conference, Low Temperature and Waste Heat Use in Energy Supply Systems},
abstract = {Das im Rahmen des Forschungsschwerpunktes EnEff:Stadt durch das BMWI geförderte Projekt "HighTech-LowEx: Energieeffizienz Berlin Adlershof 2020" hat sich zur Aufgabe gesetzt, ein ganzheitliches Energiekonzept für den Technologie-und Wissenschaftsstandort Berlin Adlershof/Johannistal zu entwickeln. Das Vorhaben strebt das Ziel an, den Bedarf an Primärenergie innerhalb des gemischten Gewerbe-und Wohnquartiers um 30% gegenüber dem "Business as usual" zu senken. Ein Arbeitspaket befasst sich mit technologischen Möglichkeiten zur Abwärmenutzung. Dies erfordert zunächst eine qualitative und quantitative Bewertung von Abwärmepotentialen hinsichtlich ihrer Herkunft sowie ihres örtlichen und zeitlichen Auftretens. Auf der Grundlage einer energetischen Analyse über das Projektgebiet konnte ein technisch nutzbares Abwärmepotential von mehreren MW festgestellt werden, das im Wesentlichen aus Lüftungs-und Klimaanlagen resultiert und sich im Temperaturbereich von 35-40°C bewegt. Das niedrige Temperaturniveau und die zeitliche Fluktuation der Wärmeströme machen eine Verwertung in herkömmlichen Energiewandlern schwierig. Dennoch erlauben unterschiedlichste Prozesse, in denen Salzlösungen mit hoher Energiedichte zum Einsatz kommen, eine Nachnutzung oder Rückführung speziell dieser niedrigexergetischen Abwärmemengen. Einerseits kann die hygroskopische Eigenschaft spezieller Salzlösungen beispielsweise genutzt werden, um industrielle Trocknungs-und Lüftungsvorgänge in ihrer energetischen Effizienz zu verbessern. Andererseits können über urbane Dach-und Fassadengewächshäuser mit Hilfe von Solarenergie große Mengen von warmer feuchter Luft als potentielle Wärmequellen erschlossen werden. Vorhandene Abwärmequellen im Entwicklungsgebiet werden zur Regeneration der Salzlösung verwendet, bei der die aufgenommenen Wassermengen wieder an die Umwelt abgegeben werden. Als räumliche Verbindung zwischen den Nutzern der Sole und den Lieferanten von Regenerationswärme kann ist Solenetz notwendig. Angebots-und Nachfragespitzen können über Solespeicher ausgeglichen werden. Speicherung und Transport erfolgen dabei ohne nennenswerte thermische Verluste. Die Energiedichte liegt bei etwa dem dreifachen Wert von Fernwärmesystemen, so dass auch größere Entfernungen innerhalb eines Solenetzes noch wirtschaftlich erschlossen werden können. In Kooperation zwischen TU Berlin und der Watergy GmbH sind im Zusammenhang mit dem Projekt "HighTech-LowEx: Energieeffizienz Berlin Adlershof 2020" Konzepte zur Nutzung von Niedertemperaturwärme durch Soleprozesse entwickelt worden. Die auf diesem Wege entstandenen Ideen für den gewerblichen Bereich der Trocknung aber auch für die Anwendung zur Raumluftkonditionierung und zur Wärmerückgewinnung werden im Rahmen dieser Veröffentlichung dargestellt. Die technische Realisierung der vorgestellten Entwürfe wird in einem geplanten Umsetzungsvorhaben weiter verfolgt.

Nutzung von Sole als Energieträger und... (PDF Download Available). Available from: https://www.researchgate.net/publication/265598675_Nutzung_von_Sole_als_Energietrager_und_Speichermedium_in_einem_urbanen_Entwicklungsgebiet [accessed May 30 2018].},
keywords = {Raumluftkonditionierung, Solargewächshäuser, Solenutzung, Wärmerückgewinnung},
pubstate = {published},
tppubtype = {conference}
}

@article{Buchholz2012b,
title = {Einsatz von Regen-oder Grauwasser in Gewächshäusern mit FeuchtluftSolarkollektoren},
author = {Martin Buchholz},
url = {https://www.researchgate.net/profile/Martin_Buchholz2/publication/299748711_Einsatz_von_Regen-oder_Grauwasser_in_Gewachshausern_mit_FeuchtluftSolarkollektoren/links/5704dd1008ae74a08e24ea10/Einsatz-von-Regen-oder-Grauwasser-in-Gewaechshaeusern-mit-FeuchtluftSolarkollektoren.pdf?origin=publication_detail},
year = {2012},
date = {2012-01-01},
booktitle = {fbr-wasserspiegel},
keywords = {Feuchtluft-Solarkollektor, Gewächshäuser, Solargewächshäuser},
pubstate = {published},
tppubtype = {article}
}

@article{Geyer2012,
title = {Parametric systems modeling for sustainable energy and resource flows in buildings and their urban environment},
author = {Philipp Geyer and Martin Buchholz},
url = {http://www.sciencedirect.com/science/article/pii/S0926580511001427},
doi = {https://doi.org/10.1016/j.autcon.2011.07.002},
issn = {0926-5805},
year = {2012},
date = {2012-01-01},
journal = {Automation in Construction},
volume = {22},
pages = {70 - 80},
abstract = {This paper proposes Parametric Systems Modeling (PSM) as a tool for building and city planning. The method outlined is based on Systems Modeling Language (SysML). It supplements geometry-based Computer-aided Design (CAD) with a non-geometric, design-oriented modeling approach that considers multidisciplinary information and parametric interdependencies. Its application is intended for the exploration of innovative sustainable design solutions at the system level. An innovative urban building-greenhouse system illustrates how the approach works for urban system design. This system features closed water cycles, renewable energy production and use, thermo-chemical energy accumulation and transport of energy for heating and cooling, as well as transformation of biomass into pyrogenic carbon. Finally, the dimensioning of the system model determines the required land areas for sustainable supply and shows that the system configuration has features of a carbon-absorbing city and thus exceeds the concept of a zero-emission city.},
note = {Planning Future Cities-Selected papers from the 2010 eCAADe Conference},
keywords = {CO-absorbing city, Parametric systems modeling, Sustainable urban system, Systems design and engineering, Zero-emission city},
pubstate = {published},
tppubtype = {article}
}

@conference{Buchholz2018,
title = {Heating and cooling with sun and salt – a thermo-chemical seasonal storage system in combination with latent heat accumulation},
author = {Marco Schmidt and Philipp Geyer and Claus Steffan and Martin Buchholz and Reiner Buchholz},
url = {https://www.researchgate.net/publication/264876417_Heating_and_cooling_with_sun_and_salt_-_a_thermo-chemical_seasonal_storage_system_in_combination_with_latent_heat_accumulation},
year = {2009},
date = {2009-01-01},
series = {World Climate & Energy Event},
abstract = {As an alternative to the pure accumulation of sensible heat, this paper discusses the storage of latent heat with different methods. Possible disadvantages to these options include the relatively high costs for the storage media, which are required in large quantities for seasonal accumulation. Thermo-chemical storage media, like absorption systems, decrease this required volume because a great amount of latent heat is involved in the absorption process. Absorption systems are also considered a base technology for solar cooling applications. The goal for the development of the "Watergy" technology described in this paper is to provide an economical absorption system for both competitive solar seasonal heat accumulation and for solar cooling, with consideration also for water efficiency. The resultant system integrates all components of a closed absorption machine, including all its potential benefits.

Heating and cooling with sun and salt – a... (PDF Download Available). Available from: https://www.researchgate.net/publication/264876417_Heating_and_cooling_with_sun_and_salt_-_a_thermo-chemical_seasonal_storage_system_in_combination_with_latent_heat_accumulation [accessed May 30 2018].},
keywords = {latent heat accumulation, solar cooling, solar thermal system, thermo-chemical seasonal storage},
pubstate = {published},
tppubtype = {conference}
}

@inproceedings{Geyer2009,
title = {Decomposition and System Layout for Multidisciplinary Design Optimization of a Seasonal Heat Storage System Integrated in Buildings},
author = {Martin Buchholz and Marco Schmidt and Philipp Geyer and Reiner Buchholz},
year = {2009},
date = {2009-01-01},
journal = {Computing in Civil Engineering},
series = {EG-ICE Conference},
keywords = {energy storage, thermo-chemical seasonal storage},
pubstate = {published},
tppubtype = {inproceedings}
}

@article{Zaragoza2008,
title = {Closed greenhouses for semi-arid climates: Critical discussion following the results of the Watergy prototype},
author = {Guillermo Zaragoza and Martin Buchholz},
url = {http://doi.org/10.17660/ActaHortic.2008.797.2},
doi = {10.17660/ActaHortic.2008.797.2},
year = {2008},
date = {2008-01-01},
journal = {International Society for Horticultural Science},
volume = {2008},
number = {797},
pages = {37-42},
abstract = {The Watergy first prototype of a closed greenhouse minimizes the use of water and energy. It has been operating since autumn 2004 in the semi-arid region of El Ejido in Almería, Spain. A balance with the main conclusions from the evaluation of the prototype is presented. A healthy crop has been maintained inside the greenhouse during all seasons, improving the production with respect to traditional open greenhouses and achieving a drastic reduction of the water consumption (about 80%). One of the main challenges has been to keep the temperature below 35°C with its passive cooling system. Several strategies have been followed and the results are outlined. Another sensitive point has been the short durability of the anti-fog property of the plastic cover material. The implications of both aspects in further designs are discussed.},
keywords = {anti-fog cover, closed greenhouse, CO2 enrichment, water conservation},
pubstate = {published},
tppubtype = {article}
}

@book{Buchholz2008,
title = {Overcoming Drought A scenario for the future development of the agricultural and water sector in arid and hyper arid areas, based on recent technologies and scientific results},
author = {Martin Buchholz and Marco Schmidt and Redouane Choukrallah and Steffen Foellner and Mirko Haenel and Karim Bourouni and Atef Hamdi and Mohammed El Mourid and Habib Ketata and Ali Nefzaoui and Mohamed Boutfirass},
editor = {Martin Buchholz},
url = {https://www.researchgate.net/publication/299748205_Overcoming_Drought_A_scenario_for_the_future_development_of_the_agricultural_and_water_sector_in_arid_and_hyper_arid_areas_based_on_recent_technologies_and_scientific_results},
year = {2008},
date = {2008-01-01},
abstract = {The Cycler Support project, funded by the 6 th Framework Programme of the European Union was aimed at bringing together knowledge from different research areas, mainly from greenhouse horticulture and water management, to investigate the potential of growing food on the base of unconventional water sources. This includes on one hand the integrated crop production using the urban water and matter cycle as a base for water and plant nutrients. On the other hand, also technologies of rainwater harvesting and water desalination are investigated. A long term scenario is described, that shall envisage a future sustainable economic base and the development of 100 % of the surface in the perimeter of urban areas in arid and hyper-arid regions. This includes high productive crop production within a new generation of water efficient greenhouses, but also reflects the development of the open landscape, that can be developed e.g. by changing the relief and by adding non-degradable carbon being generated as a waste product from the urban matter cycle. New generation greenhouses:A group of new greenhouse technologies allows to collect condensed water from air water vapour within greenhouses. This means, that much less conventional water has to be used. Together with rainwater collected from the roof tops of the greenhouses, it is possible to reach a water autonomous situation of irrigation water supply in many regions of the world. Urban greywater can be used as an additional water source in irrigation and can be recycled back as fresh water in the urban areas. Saline water can be used in the greenhouses for evaporative cooling in a way, that also the condensed water yield is increased. Seawater can be directly used for irrigation directly, if it’s sufficiently mixed with condensed water, so that the salinity is decreased and can be managed by salt uptake of the vegetation and periodical flushing of drainage water. A first example for the new technology is the Watergy greenhouse, a closed air environment. There is an internal, buoyancy driven air circulation with rising hot and humid air, that flows up into a tower. Within a cooling duct, the air then is cooled downd by a heat exchanger, that makes the the air cooler and heavier, so it flows down, back into the greenhouse. The water that has been evaporated by the plants in the greenhouse and by additional air humidifiers in the greehouse roof is condensed back by the cooling process. A specific advantage of a closed greenhouse is, that no insects can enter, so that pesticides can be ambundant. Additionally, carbon dioxide can be accumulated in the closed system as a plant fertilizer. Already now, a 100% additional crop productivity has been approved within this prototype, mainly due to the CO2 enrichment. Growing larger amounts of crops at higher quality means a big economical advantage for farmers. Another new generation greenhouse type is the seawater greenhouse. It has been developed by the british company “Seawatergreenhouse”. It is an open system with a linear air flow. There is a fan that blows air out of the greenhouse. Fresh air is comig in but is cooled by evaporation pads at the greenhouse air inlet using seawater for evaporation. This means that cool air can be provided relatively cheap, if seawater is availlable in the local neighbourhood. The water, that has been evaporated by the plants and the water vapour from the pads can be condensed out of the air by a cooling wall. In this way, a large amount of water intorduced into the system can be recycled. 9 To go beyond the stage of using ventilators, that are very energy consuming, it is proposed to develop a new kind of slope greenhouse, that can use the buoyancy effect to induce air exchange. Again, it is possible to use seawater for evaporative cooling of the incoming air and greenhouse crop production can be performed in the area behind the cooling pads. In a second compartment along a mountain slope, the growing air temperatures can be used to evporate more seawater from ponds, that can be placed within several terraces. This part can be combined with algae production as these species, compared with higher plants, can tolerate hotter temperatures as well as increased water salinity. Finally, a simple air to air heat exchanger can be placed at the upper outlet of the greenhouse system to cool down the hot and humid air and to force condensation. The greenhouse could change both, the surface heating effect and the related desiccation of the air, and by this will contribute to fight against the negative climatic effect of hot spots, hindering rainfall in coastal areas due to insufficient evaporative cooling of vegetation surfaces. Productive system using the urban water and matter cycle.A general risk in Mediterranean countries and other arid and hyper-arid areas on the world is growing drought and water scarcity, that destroys the base of food supply and the most important export business for many regions. Insufficient waste water treatment is also the base for groundwater contamination and related problems with diseases. Treated wastewater from clearage fields can be filtered with a specific gravel filter. The drainage from these filters can be used for irrigation water supply of the new generation greenhouses. The risk of food contamination until now hinders applications like this in the official agricultural policies. It is proposed to first evaluate the quality of the water before and after the new gravel filter and within the final crops in detailed field studies For the case of insufficient crop quality, it is proposed to use membrane ultra filtration, which is a more expensive method, but still much less energy intensive than for example sea water desalination. Both filters have the specific advantage, that plant nutrients can remain in the water and can be used for crop production. An alternative for the treated waste water from clearage fields is the direct separation of greywater and urine within the households. In this case, the water can be directly treated by the gravel filter or even can be used directly for irrigation and the greenhouse irrigation system itself is used as a treatment facility. The final product is fresh food and clear water, that can be sold on the local market as well as for export. For the case, that gravel filter or ultra filtration does not allow a sufficient crop quality, it is also possible to irrigate non-food crops within the greenhouses, that can for example be used as a base for construction materials. Here we have the risk concerning an insufficient value of non-food products, that would not allow capital intensive greenhouse production. For that case, it is proposed to further develop greenhouse integrated solid state fermentation, that allows to produce industrial raw materials like improved textiles and cellulose, materials that have a much higher value than just raw biomass. Bamboo could replace steal and biologically treated hemp could replace cotton, but both products could be produced with obviously lower energy and water consumption, compared to the products that can be substituted. 10 Solid state fermentation can also be used to produce protein enriched food from oil or starchy crops like soy, peanut, rice or potatoes that can provide a valuable substitute for fish and meat. Again, these products can be produced with obviously lower energy and water consumption, compared to the products that can be substituted. These examples show the potential of increased surface productivity, far beyond just using biomass as an energy source, that can launch up totally new markets for the greenhouse business. Integrating saline water in the greenhouse water cycle: Seawater can be used as an additional water source, especially for coastal areas, that could even allow a total independency from rain. In the closed greenhouse, seawater can be used for humidification of greenhouse air in the roof area as well as during night, using the stored thermal energy with having condensation yields on the greenhouse roof. For the open slope greenhouse, seawater can be used for the cooling of the incoming air as well as for the slope greenhouse, for the solar still in the slope part behind the crop area. In this way, a much more water independent production of crops and biomass can be introduced. A specific problematic wastewater in coastal areas is coming from the fish industry, as it increases the total salinity of urban wastewater, thus making it problematic for reuse in irrigation. It is here proposed to separate this kind of wastewater and to use it as a nutrient source for aqua farming. Seawater can be used to dilute this wastewater to decrease its salinity. The runoff water from the aqua farming can still be used as a nutrient source for algae production, thus allowing a total removal and use of the organic residues. Algae production can be integrated into the solar still part of the slope greenhouses. Pyrolysis, as a pollutant sink in the urban matter circuit, producing a non-degradable soil improver as a by-product: Looking at the waste stream after the product’s life cycle, the wastewater has already been mentioned. Organic solid waste can be divided into agricultural waste, which for example can be contaminated with pesticides and domestic waste, that can also contain toxic constituents. The risk of accumulation of pollutants in closed matter circuits can be minimised by having pyrolysis as a general treatment method for solid waste. Beside having the possibility of producing oil and gas with this method, residues from the process like charcoal and carbon dioxide can be redirected into the greenhouse areas. How does pyrolysis work? Agricultural residues, domestic solid waste and sludge has to be dried, using solar energy. This can be done as a common method either on open fields or in open greenhouses. The dried biomass is transported to a centralised pyrolysis device, where it is processed into oil, gas and solid charcoal. The oil can be used as an export good. It needs post processing, that can be done in a more decentralised unit. The gas can be used locally in combustion units, while the produced carbon dioxide from that units can be used for CO2 supply in closed greenhouses. The charcoal can be used as a permanent, non degrading soil improver at the productive land, that , as a positive feedback enhances the production of the biological resources. Combined recovery of water from greenhouse irrigation and of cooling water from concentrating solar thermal power stations (CSP): On the scale of a whole region, greenhouse areas can be placed on the perimeter of cities, producing food for export and for the local market. Electricity can be produced by concentrating solar power stations, that can be used in combination with the greenhouses, using common heat storages for cooling purposes, without increasing the volume of these storages, as it is possible to just increase the 11 temperature amplitude, which for the greenhouses ranges between 25 and 40°C and for the power stations between 40° and ~45° C. The stored heat can be used in combination with seawater desalination in the solar still of the slope greenhouse or in closed greenhouses during night with water condensation on the inside greenhouse cover. The size of the steam turbine of a concentrated solar power unit also triggers the size of one surrounding greenhouse unit. Agadir as one off the exemplary regions: The central structure of Agadir is already attached to neighboured greenhouse areas, that could be improved to provide the functions of the closed urban water and matter circuit. For the further growth of the urban region, it is proposed to have a kind of decentralised concentration instead of further growth out of the centre. There is an area along the coastal main road with several larger villages, there is Biugra as the largest satellite town and there is a chain of villages along the road to the city of Taroudant. These areas have direct contact to the surrounding landscape. They can be further developed for the integration of the urban matter circuits and energy flows, providing a sufficient supply of labour, food, water and energy. Finally a supply system for seawater is proposed. It can be used as an additional water source in the greenhouse areas, that will allow the regional production system to be more or less totally independent from rainfall. Agadir, the metropolitan area of Southern Morocco at the edge of the desert by this could be an example for new cities southbound the coast and for other hyper arid regions of the world. Policy and Research recommendations: The innovative, multifunctional character of the new proposed systems as a productive unit for food/non-food crops and clean water on the one hand, and a treatment system for wastewater and saline water on the other, requires support on policy and administrative level to speed up the implementation of these technologies. Starting up programmes to support implementation of the ECOSAN approach (incl. wastewater separation and safe reuse) are proposed. Based on the implementation of existing standards on wastewater reuse, a supporting development of adapted standards for new generation greenhouse systems is discussed. Recommendation for regional action plans, enabling wastewater reuse are given. For the context of greenhouse horticulture, a label for sustainable agricultural production including sustainable use of water is proposed. Closed greenhouses in combination with pyrolysis waste treatment shall be officially confirmed as a carbon sink in the international carbon trade system. Cooling water recovery of concentrated solar power units and methods for using the waste thermal energy for solar desalination processes within greenhouses should be supported by specific CSP directives and should be included in related subventions. Coastal saline water supply networks can be developed as a part of regional infrastructure planning. For near term measures, a number of 10 model research areas are proposed, being (1) closed greenhouse research for food crops, (2) research for non-food crops including greenhouse integrated solid state fermentation, (3) open greenhouse research with natural convection, built on mountain slopes, using saline water from the sea for evaporative cooling, (4) integrated aqua farming for fish and algae production using waste water and solid waste from fish processing, (5) formation of model urban areas for wastewater pre-selection with related use of greywater and treated urine in greenhouse projects (6) wastewater post treatment systems adapted to reuse of water and solved plant nutrients in horticultural production systems, (7) sea- and brackish water desalination systems adapted to use in horticultural production, (8) pyrolysis model project for treatment of urban waste, sludge and agricultural waste with charcoal as a main output product to be used as a soil enhancer, (9) rain fed cultivation in arid areas based on charcoal soil supply and surface rainwater harvesting and (10) concentrated solar power projects with cooling water recycling in closed greenhouses

Overcoming Drought A scenario for the... (PDF Download Available). Available from: https://www.researchgate.net/publication/299748205_Overcoming_Drought_A_scenario_for_the_future_development_of_the_agricultural_and_water_sector_in_arid_and_hyper_arid_areas_based_on_recent_technologies_and_scientific_results [accessed May 30 2018].},
keywords = {arid area, closed greenhouse, CO2, seawater greenhouse, solar energy, wastewater},
pubstate = {published},
tppubtype = {book}
}

@conference{Zaragoza2007,
title = {Experiences in cultivation inside the watergy prototype of a closed greenhouse for semi-arid regions},
author = {Guillermo Zaragoza and Martin Buchholz and D Buendia and D Meca and J Pérez-Parra},
url = {http://doi.org/10.17660/ActaHortic.2008.801.90},
doi = {10.17660/ActaHortic.2008.801.90},
year = {2007},
date = {2007-01-01},
booktitle = {Acta Horticulturae - Greensys2007},
volume = {801},
pages = {773-780},
publisher = {ISHS},
abstract = {A prototype of a closed greenhouse has been constructed in the semi-arid region of El Ejido in Almería, Spain. It is a plastic greenhouse which minimizes the use of water and energy. This work presents the agronomical evaluation of the system during the first three years of operation, when several cycles of cropping have been performed in different seasons, all of them in a closed water cycle with the recovery of evapotranspiration and drainage, and with an enhanced concentration of CO2 in the air (1000 p.p.m.). Production data are given for two autumn and two spring cycles of beans (Phaseolus vulgaris), as well as for one summer cycle of okra (Abelmoschus esculentus). The yield results, together with those of the productivity of water, are compared with the standards for the region and, in the case of one spring cycle of beans (cv. Strike), with a similar crop grown simultaneously in an open greenhouse. Better production, and a much higher efficiency in the use of water is achieved in the closed greenhouse.},
keywords = {carbon dioxide enrichment, closed greenhouse, closed water cycle, greenhouse cooling},
pubstate = {published},
tppubtype = {conference}
}

@conference{Buchholz2006a,
title = {Projekt Watergy: A closed Greenhouse for minimized Water consumption and optimized solar energy},
author = {Guillermo Zaragoza and Patrick Jochum and Buendiía Pérez and Martin Buchholz and Reiner Buchholz},
url = {http://www.publicacionescajamar.es/series-tematicas/centros-experimentales-las-palmerillas/project-watergy-a-closed-greenhouse-for-minimized-water-consumption-and-optimized-solar-energy-use/},
year = {2006},
date = {2006-11-01},
booktitle = {CIES 2006},
series = {XIII Congresso Ibérico e VIII Congresso Ibero-Americano de Energia Solar},
abstract = {Watergy project is funded by the European Community’s Vth Framework in its Energy, Environment and Sustainable Development program. It consists of the development of a humid air solar collector system that follows the principle of a closed two phase thermosyphon. A combination of evaporation and condensation allows to use solar thermal energy in a much more efficient way. The main advantage is not only the reduction of costs in space cooling and heating, but the possibility of water purification, as the system can be fed with low quality water to obtain distilled water. The decentralization of heat and water supply opens the possibility of residential areas where greenhouses fed with low quality water (grey water and brackish water) could be used to produce distilled water as well as heat and fruits. The project contemplates the development of two prototypes: one application for arid climates in Southern Europe with an emphasis on water production in the context of greenhouse horticulture, and another for temperate Central European climate focused on heat and water production for sustainable architecture.},
keywords = {closed greenhouse, closed water cycle, solar greenhouse, Solar thermal energy},
pubstate = {published},
tppubtype = {conference}
}

@conference{Buchholz2006,
title = {Temperature and humidity control in the watergy greenhouse},
author = {Martin Buchholz and Reiner Buchholz and P Jochum and Guillermo Zaragoza and Jeronimo Pérez-Parra},
url = {http://doi.org/10.17660/ActaHortic.2006.719.45},
doi = {10.17660/ActaHortic.2006.719.45},
year = {2006},
date = {2006-01-01},
booktitle = {International Society for Horticultural Science},
journal = {Acta Horticulturae},
volume = {719},
number = {45},
pages = {401-408},
abstract = {A closed greenhouse with passive cooling and dehumidification strategy is described, allowing a reduction of water consumption of 75% and continuous plant production even during hot summer conditions in Southern Spain. Main points of examination are how the air temperature and humidity in the closed greenhouse could be kept in the allowed range without using external energy except solar energy and how a growth cycle of crop could be held successfully and plants used in a satisfying way to purify water.},
keywords = {air dehumidification, closed greenhouse, desalination, greenhouse cooling, water recycling},
pubstate = {published},
tppubtype = {conference}
}

@article{Zaragoza2006,
title = {Watergy project: Towards a rational use of water in greenhouse agriculture and sustainable architecture},
author = {Patrick Jochum and Jeronimo Pérez-Parra and Guillermo Zaragoza and Martin Buchholz},
url = {https://www.tib.eu/de/suchen/id/BLSE%3ARN208778673/Watergy-project-Towards-a-rational-use-of-water/},
issn = {0011-9164},
year = {2006},
date = {2006-01-01},
journal = {Desalination},
volume = {211},
number = {1-3},
pages = {296-303},
keywords = {closed greenhouse, closed water cycle, CO2 enrichment, greenhouse cooling, solar greenhouse, water recycling},
pubstate = {published},
tppubtype = {article}
}

@conference{Jochum2005,
title = {How to Simulate Thermal and Fluid Dynamical Processes in Closed Greenhouses including Water Interactions between Plants and Air},
author = {Patrick Jochum and Martin Buchholz},
url = {http://doi.org/10.17660/ActaHortic.2005.691.66},
doi = {10.17660/ActaHortic.2005.691.66},
year = {2005},
date = {2005-01-01},
journal = {ISHS Acta Horticultuare},
volume = {691},
series = {International Conference on Sustainable Greenhouse Systems - Greensys2004},
abstract = {A new type of greenhouse is presented. It is a closed system using buoyancy as driving force for ventilation. The greenhouse is equipped with a tower in which the air is cooled or heated to maintain the inner temperatures in the required band and then conducted back to the plants. During the cooling process the water in the humid air condenses and can be reused. The subject of this article is the way of prediction of the thermal behaviour of closed greenhouses by means of dynamic simulations. Several model approaches are discussed. The simulation environment Smile is presented as a flexible program for this purpose.},
keywords = {CFD, closed greenhouse, natural ventilation, simulation, Smile, thermal and pressure node model, water treatment},
pubstate = {published},
tppubtype = {conference}
}

@phdthesis{Buchholz2002,
title = {Energiegewinnung, Wasseraufbereitung und Verwertung von Biomasse in Gewächshaus - Gebäude - Modulen},
author = {Martin Buchholz},
url = {https://doi.org/10.13140/RG.2.1.1035.0486},
year = {2002},
date = {2002-01-01},
publisher = {Unpublished},
school = {Technische Universität Berlin},
abstract = {Until now, economical use of heat and vapour from greenhouse air has been hin dered by the following problems: The heat resistance of plants is too low to allow acceptable flow temperatures for heat accumulation (Meyer et al., 1989). In open systems, air exchange for cooling, vapour removal, and CO2 accumulation results in high energy and water losses. In closed systems, heat exchangers fed by elec tric fans have a negative impact on the overall energy balance. (Bredenbeck 1992). The system consists of an air circuit, formed by four main items. A conventional greenhouse is connected with vertical, glass-covered air tubes functioning as a solar chimney. In the feedback duct, a large air-water heat exchanger is installed and connected with a heat accumulator. The air then passes into a reactor for solid state fermentation. Within this essentially closed system, greenhouse plants and fermentation micro organisms supply each other with oxygen and carbon dioxide. In the greenhouse, incident solar power is predominantly converted by water transpiration of plants. Since air warms up very slowly compared with a sealed surface, energy is stored in the damp air. In the solar chimney, air warms up directly and rises, drawing air upwards out of the greenhouse. At the top of the chimney, the strongly heated air passes a humidifier, initiating a first step of cooling. In the feedback duct, air is strongly cooled by a large heat exchanger, causing it to fall. The water vapor from the greenhouse and from the humidifier condenses, releasing thermal energy. The air then passes into a reactor for solid state fermentation. Here, plant or waste biomass substrates are modified by special fungi. Within this essentially closed system, greenhouse plants and fermentation micro organisms supply each other with oxygen and carbon dioxide. Finally, the cooled air rises back into the greenhouse by warming up in the fermentation device and by the lift suction from greenhouse and chimney, thus closing the cycle. Air circulation in the system is driven by the temperature-related pressure drop between the top of the chimney and the bottom of the heat exchanger. Energy transfer in the heat exchanger and the process of evapotranspiration are strongly supported by the induced kinetic energy of moving air. Solid State Fermentation (SSF) refers to the growth of micro organisms on solid substrates without the presence of free liquid between substrate particles. It is of particular interest where natural materials are used, such as wood, agricultural byproducts or foodstuffs. The raw materials act as the main source of nutrients and the organisms release enzymes which break down and modify the solid mate rials. Substrates serve as a nutrient source for the microorganisms, as a CO2 -source for the greenhouse plants and - by releasing process heat - as an energy source. Simple applications include the production of composts or the decontam ination of soil. More sophisticated alternatives include the production of tropical mushrooms or tempe-like foods and the protein-enrichment of potatoes (Senez et al.,1977; Steinkraus 1982) Bautista et al.,1989). Methods for delignifying woody particles in paper/textile production using white-rot fungi are still at the research stage (Valmaseda et al.,1991, Saucedo-Castaneda et al. 1990). Applications of this latter type are of particular interest, since most of the planet's vegetable biomass takes the form of lignocelluloses. The air cycle brings oxygen from the greenhouse and removes process heat and CO2. The heat and CO2/O2 exchange processes involved in solid state fermen tation are optimised by channelling air through stacked trays, so-called tray biore actors, or through a mixing device, a rotating drum bioreactor. (Rehm/Reed 1987). The high air humidity helps prevent the substrate from drying out, which is important due to the relative complexity of achieving uniform irrigation/re-hydration of substrates (Sangsurasak et al., 1995). The system most used at present, submerged fermentation in sterile, sugar-based nutrient solutions, causes high energy costs for sterilization, climate control, oxy gen support and mixing. Sugar as the main substrate is another cost factor. This system is therefore only suitable for high-grade products. In SSF , on the other hand, low cost materials like wood-chips, reed-straw or agricultural by-products can be processed. Energy costs can be minimized by the described climatisation technology. If exothermic processes are harnessed, it is even possible to achieve a positive energy balance. By controlling the process with different parameters like enlarging the spore inoculation and optimising climate, substrate humidity or pH-value, certain microbes can be grown under non-sterile conditions. Besides the resulting limitation to relatively few suitable micro organisms, a major disad vantage of this system is the extreme slowness of the process. Decentralized pro duction in very simple, high capacity models within greenhouses overcomes this problem to a certain extent. Optimisation for Water Treatment. The mechanism of energy flow can be reversed for night operation. The daytime heat output is stored and returned at night via the heat exchanger, with the air now moving in the opposite direction. The air humidifier can be operated 24 hours. At night, steam condenses on the cool exterior sur faces of chimney and greenhouse. The heat accumulator stores chilled water to run the cooling function the following day. Desert or near-desert climate conditions with strong day/night fluctuations of temperature favour this type of process. Greywater from a residential building can be used for irrigation in the greenhouse. Water from condensation can be returned to the building for reuse. Additionally, salt or brackish water or contaminated ground or surface water can be fed into the system via the air humidifier. Due to the high recycling rate, a water surplus can be achieved, allowing additional buildings to be supplied with water. Greywater from these buildings can then be used to irrigate surrounding vegetation. Optimisation for Solar Heating In colder climate zones, it may make more sense to optimise the system for local heat supply. The necessary temperature difference has to be stretched from a day/night cycle to a seasonal one. Summer heat is used to load a long-term sea sonal heat accumulator. During winter, this warmth is used to run a heating system in a building. At the same time, the accumulator stores cold water to provide the cooling function for the air circuit during summer. There are various options for optimiing the charge/discharge process of the heat accumulator. A heating cascade from the residential building to the greenhouse provides low temperate heat for a greenhouse temperature of 1-15°C and a sim ilar storage temperature for the cooling functions in summer. The main energy source for greenhouse heating is the composting of organic waste in the fermen tation unit. A modified absorption heat pump may be added for further optimisa tion. For this, the accumulator is filled with a mixture of water and ammonia. By passing the heat exchanger and a further, conventional solar heat collector, ammonia becomes separated due to its lower boiling point. It can be condensed and stored under normal pressure. (Holldorff, 1981) The water is heated further and fed into the heat accumulator. In the discharge phase (in winter) ammonia evaporates at the radiator outlet of the heating system, cooling it down from about 25°C to 5°C. During sunny winter days, the cooling function of the air circuit can be driven by releasing additional ammonia to exploit energy from low temperature solar and composting sources. In the absorber, ammonia vapour and water become reunified, releasing high temperature heat according to the principle of an absorption heat pump. Water Purification In temperate climates - especially in winter - only a small part of the produced greywater can be evaporated in the greenhouse. By passing the greenhouse, considerable levels of purification can be achieved, allowing the resulting water to be channelled above ground into open ditches, thus reducing pressure on sewage systems. This could also substantially reduce the cost of developing urban areas. The water can be channeled into natural wetlands like reed-fields, wet meadows or damp forests. Here, plants grow rapidly due to high water and nutrient levels and can be used in the fermentation reactors as a source of energy and raw mate rials. Using this approach, the agricultural control mechanisms for growing and processing regenerative raw materials could be radically changed. Functions like plowing, sowing, plant protection or fertilization could be partially replaced by sim pler, cheaper mechanisms like terracing, greywater irrigation and compost fertilization and by periodically harvesting the fast growing plant matter. High quality processing results and use of this kind of raw materials are only made possible by the fermentation component.
Energiegewinnung, Wasseraufbereitung und... (PDF Download Available). Available from: https://www.researchgate.net/publication/299748215?channel=doi&linkId=5704d9cf08ae13eb88b6bf55&showFulltext=true [accessed May 30 2018].},
keywords = {Biomasse, Energiegewinnung, Gewächshäuser, Wasseraufbereitung},
pubstate = {published},
tppubtype = {phdthesis}
}