A Concept for Reduced Energy Demand of Greenhouses: The Next Generation Greenhouse Cultivation in the Netherlands

Abstract

In high tech greenhouse cultivation like in The Netherlands, large amounts of fossil energy are used to optimize climate conditions like temperature and humidity. To achieve a more sustainable greenhouse horticulture, a considerable reduction in energy use is needed, but tradeoffs with production and quality are not acceptable. Therefore, we developed a novel cultivation system for tomato to meet the goal: reduction of the energy input by 40% from 1.3 to 0.75 GJ.m-2 .y-1 , maintaining a production level of 60 kg.m-2 .y-1. This concept, the Next Generation Greenhouse Cultivation, is based on the intensified use of thermal screens combined with control of humidity, maximizing the use of the integration capacity of the crop, growing at high humidity, improved efficiency of CO 2 supply by reduction of ventilation and the use of cooling combined with a heat pump and an aquifer. In this approach, the main element is the prolonged use of screens with a high insulating value (>70%) to reduce the energy demand, combined with a forced ventilation system that injects relatively dry outside air into the greenhouse. The maximal use of the integration capacity of the crop implies a strong relation between daily radiation sum and diurnal mean temperatures, and a large difference between night and day temperatures on sunny days. This reduces the energy input and ventilation rate. Growing at increased humidity, achieved by misting, reduces ventilation rates because of the increased enthalpy of the greenhouse air. When supplying CO 2 , reduced ventilation results in higher CO 2 concentrations and hence a higher energy efficiency. Cooling can be used in combination with a heat pump and an aquifer to reduce the need for fossil fuel. This approach, in which proven technologies are combined, enables growers to implement the elements step by step, leading to an easy acceptance.

Validating the Concept of the Next Generation Greenhouse Cultivation: An Experiment With Tomato

“…A concept for a new growing system for tomato with a great reduction of energy demand was developed with the knowledge of experts and the application of models (De Gelder et al, 2012). This experiment was carried out to validate this concept.…”

Crop growth and development in closed and semi-closed greenhouses

“…Approximately 2800-3000 MJ m -2 y -1 solar energy is entering a greenhouse in the northwest part of Europe (Bakker et al 2006). An open greenhouse in the Netherlands with tomatoes consumes about 30-40 m 3 m -2 y -1 natural gas, equivalent to 930-1240 MJ m -2 y -1 energy, mainly for heating (Bot et al 2005;De Gelder et al 2012b;De Zwart 2012). Hence, on an annual basis the solar energy entering the greenhouse is more than twice the energy consumption in the greenhouse.…”

“…In the beginning, the development of closed greenhouses was primarily focused on the technical possibilities of the system (Bakker et al 2006;Buchholz et al 2005;Bot et al 2005). Further research on plant growth and development in the closed greenhouse followed (Hoes et al 2008;Luomala et al 2008;Grisey et al 2011;De Gelder et al 2012b;Dannehl et al 2014), because knowledge on crop response to the climate condition in the closed greenhouse was needed for making optimal use of the new system during implementation. Improving sustainability of the greenhouse production systems needs control of growth conditions in the greenhouse to meet the demand of the crop, while the crop management should aim at a crop that suits better the growth condition in the greenhouse (Marcelis and De Pascale 2009;Dieleman and Hemming 2011).…”

“…This knowledge has been used in the development of the concept of the next generation greenhouse cultivation. This concept strives to reduce the energy consumption for heating without reducing yield and quality of the produce (De Gelder et al 2012b), at much lower investment costs than the closed greenhouses. The main elements of this concept are 1) Improving insulation by application of multiple screens; 2) Controlling air humidity by forced ventilation.…”

Energy saving by LED lighting in greenhouses : A process-based modelling approach

“…Studies in the field of optimal control (Van Straten et al, 2010) showed that an improved climate control strategy can meaningfully reduce energy use (Van Beveren et al, 2015b;Van Henten et al, 1997). A new approach to crop cultivation, called the "Next Generation" greenhouse cultivation, combines design, technology and climate control with the aim of improving greenhouse energy use (De Gelder, Poot, et al, 2012). Lastly, the use of alternative energy sources does not in itself reduce greenhouse energy use, but it can meaningfully reduce a greenhouse's carbon footprint (Ntinas et al, 2020).…”