Plant husbandry – Greenhouse – apparatus or method
Reexamination Certificate
2002-03-14
2004-03-16
Poon, Peter M. (Department: 3643)
Plant husbandry
Greenhouse, apparatus or method
C165S045000
Reexamination Certificate
active
06705043
ABSTRACT:
The present invention relates to a closed market gardening greenhouse and a method for controlling the climate in a closed market gardening greenhouse.
Cultivation under glass takes place worldwide with “open” greenhouses. Open greenhouses provide the option of ventilating the greenhouse air by means of ventilating windows. This has the advantage that when insolation is high the surplus heat and/or moisture can be removed in simple manner via ventilation. In the Netherlands it is necessary on a large number of days for the greenhouses to be ventilated for a number of hours.
Optimal culture conditions however require a good balance between insolation, air humidity, greenhouse temperature and CO
2
delivery. It is self-evident that the open greenhouse system cannot usually satisfy optimal culture conditions.
Optimal culture conditions for the greatest possible harvest for many crops are as follows:
Temperature between 18 and 24° C.
Air humidity between 70 and 90%
Concentration of CO
2
: 1000 ppm.
From an energy viewpoint an open greenhouse system is not desirable.
The surplus heat in summer is after all removed by ventilation while in winter there is a heat demand.
Because an open greenhouse does not cool actively, the temperature is frequently higher than 24° C.
An open greenhouse is supplied with CO
2
. This CO
2
is necessary for the growth of the crop.
Because an open greenhouse must be ventilated often to dispose of the surplus heat and moisture, the supplied CO
2
is hereby also lost.
In an open greenhouse the crop will be able to grow quickly particularly in the summer because of high insolation, even though cultivation conditions are not then optimal: too warm and too little CO
2
. The great quantity of light is not used optimally, mainly because there is a shortfall in the concentration of CO
2
.
An object of the present invention is to provide an improved market garden greenhouse.
According to a first aspect of the present invention a market garden greenhouse system is provided in which plant products can be cultivated, which market garden greenhouse is closed and substantially not provided with ventilating openings, wherein the market garden greenhouse comprises:
heat regulating means for regulating the heat in the greenhouse, which heat originates from solar energy and a heating system, and/or
air humidity regulating means for regulating the air humidity in the greenhouse.
A closed greenhouse system according to the present invention makes it possible in principle to optimize the greenhouse climate. A closed greenhouse system according to the present invention is understood to mean a greenhouse without ventilating windows which can be opened.
In a closed greenhouse the heat and moisture will be removed without the CO
2
concentration being decreased.
With a rapidly responding climate control an optimal balance between the insolation, air humidity, greenhouse temperature and CO
2
delivery must be possible at any fluctuation in the insolation.
Advantages of a closed greenhouse according to the present invention are:
the consumption of primary energy (the greenhouse as (closed) solar collector must utilize the insolation to maximum effect) will, according to calculations, be a minimum of 40% lower than in a modern traditional “open” greenhouse.
higher cultivation yield because the cultivation conditions such as temperature, air humidity and CO
2
concentration can be better controlled and managed. On the basis of model predictions, it is the expectation that the cultivation yield will be a minimum of 20% higher than in a modern traditional open greenhouse.
the use of herbicides/pesticides can be reduced considerably because of the considerable decrease in the chance of crop diseases and infestations; and
saving in water consumption (in a closed system there is the option of collecting and recirculating all the evaporation from the crop; a greenhouse normally uses 500-600 kg/m
2
annually).
it is expected that the moment of harvesting can be better controlled. It will be possible to respond better to the market. A higher price per kg of product can hereby be anticipated. The possible favourable financial consequences of the moment of harvesting are not included in this report.
A possible option for providing CO
2
to the greenhouse is the production of CO
2
in the greenhouse itself by means of a “bacteria-rich” ground.
For the combined heating and power option with electric heat pump a study of the possibilities for CO
2
storage is furthermore of importance for the use of the locally generated CO
2
.
From the viewpoint of a renewable energy provision, a market garden greenhouse can be considered a solar collector.
For maximum use of the annual insolation the surplus radiated solar energy (in the form of sensible and latent heat) will be collected on a “warm” day and stored. Sufficient heat will have to be supplied from the store on a “cold” day.
Fluctuations in the energy demand within a day—caused by fluctuations in the outside climate—can also be compensated.
A stable inside climate requires a rapidly responding energy system.
The basis of the energy supply in the greenhouse system according to the present invention consists of a heat and cold-providing system in the form of a number of heat exchangers and air distribution units in the greenhouse. The heat exchangers have both a cooling and heating function. The air in the greenhouse is carried through the heat exchangers by means of fans; use can optionally be made of natural convection during heating.
Cooling of the Greenhouse System
The surplus heat is removed entirely to an aquifer in the summer. This takes place by active convection through heat exchangers. These heat exchangers are fed with cold water from an aquifer, see
FIG. 1
wherein A to H are liquid flows (A and B are groundwater flows).
An aquifer is understood to mean a natural water source of often non-potable water which, stored in a sand layer, lies under the ground under pressure at a depth of roughly 80 m.
An aquifer is thus a kind of “underground” lake which cannot be termed “groundwater” since there is substantially no circulation of water in an aquifer.
Aquifers are often found in delta regions in North-West Europe.
The present invention preferably makes use of existing aquifers as energy store.
The aquifer can be limited in output capacity to the flow rate which can be processed by one doublet, consisting of one borehole for upward pumping of water and one borehole for downward pumping of water in a closed circuit.
The aquifer can be dimensioned such that the peak output of heat can be removed immediately.
By applying a day storage for both cold and warm water, the peak capacity for the cooling does not have to be extracted directly from the aquifer. In the night prior to a hot day a supply of cold water is stored which is large enough, together with the cooling from the aquifer, to remove the heat surplus at a high output during the day. The cold water extracts heat from the greenhouse and is then stored in a warm day buffer and in the following night removed to the aquifer. In this way the heat supply peak is removed sufficiently quickly and removed uniformly to the aquifer via buffering.
The day buffers can be embodied as two covered, uninsulated water basins such as are currently used as water store for watering. If necessary, these day buffers can also be placed underground. It is also possible to opt for a layered storage in one buffer.
The momentary heat surplus in the greenhouse can be removed in two ways:
directly to the aquifer
indirectly via day buffer to the aquifer.
A structural heat surplus in the aquifer can be removed in two ways:
cooling with cooling tower
supplying heat to third parties outside the greenhouse.
If a heat surplus occurs in the greenhouse, this heat will have to be stored in the aquifer. The quantity of heat to be stored determines the required storage capacity of the aquifer. This heat is used for heating in the winter.
In respect of the flow rate the aquifer has the smallest possible dimensions in order to k
Blok Kornelis
Opdam Joannes Jozef Gerardus
Schoonderbeek Gilbertus Gualtherus
Ecofys B.V.
Gellner Jeffrey
Myers Jeffrey D.
Poon Peter M.
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