Heating a greenhouse is one of the most basic aspects of modern agriculture, yet the methods in which this heat is produced may seem a bit antiquated, even in countries considered to be at the forefront of both technology and environmental awareness.
This article was originally featured on www.hortidaily.com
Modern agriculture enables year-round growing in regions where nature would not otherwise allow it. This is achieved by growing in greenhouses – spaces in which climate conditions can be artificially produced and maintained. When it comes to cold climates, the most important condition to maintain is obviously – heat.
There are several methods to distribute heat around the greenhouse, but all of which have one commonality, they all require a source of energy with which the heat is created. The most common method is using a boiler, which is heated either by combustion or electricity.
In most countries, coal is readily available and relatively cheap, leading to coal burning being a significant player in global greenhouse heating.
There is an additional benefit to combustion in agriculture – combustion creates CO2, which plants need in order to photosynthesize, and therefore grow. So, the extra CO2 created is injected into the greenhouse to enrich the air and increase growth.
Many greenhouses even use co-generation burners, utilizing the heat to warm the greenhouse while using and even passing on the excess electricity created. On the surface, it seems like a win-win.
So, What’s the Problem?
It’s 2018, and there is no dispute regarding the negative effects of coal burning. It emits greenhouse gases, associated with global warming, as well as carbon monoxide which is a fatal poisonous gas. The production of coal is also extremely harmful to the environment, it requires large-scale mining, destroying lands as well as polluting the air, and potentially water sources. These are some of the reasons most governments around the world are reducing coal production and consumption, in favor of cleaner energy sources.
In addition to coal being harmful, and possibly the biggest driving force for change, it is also on the decline. Being both produced less, and taxed more, the global supply of coal is diminishing while the prices are steadily rising.
With coal being increasingly vilified, and slowly becoming more expensive, as well as less available, greenhouses around the world are on the lookout for alternatives.
Greenhouse Heating Alternatives
There are many methods to heat a greenhouse, but the bottom line is – it all boils down to availability and pricing.
The most immediate alternatives to coal burning, include the use of “cleaner” fuels, such as natural gas or biomass, such as wood chips. These methods are viable, and preferable to coal, though they follow the same path of pollution, greenhouse gas emissions and health risks.
An overlooked contender in the running for heating comes from a different angle. Technologies such as DryGair’s dehumidifiers, are ushering in a new state of mind when it comes to greenhouse climate management as a whole. The concept is to further close and insulate the greenhouse in order to maximize efficiency of the systems already at work. While they may not replace heating, they can drastically reduce the amount needed, cutting the fuel or electricity being invested into it by up to 80% energy saving per day.
Proper dehumidification allows growers to close the greenhouse, instead of ventilating, which is the traditional method of reducing humidity. But what does this have to do with heat?
When ventilating, the heat produced is quickly lost to the outdoors, new air is introduced into the greenhouse, and it needs to be heated again. When dehumidifying inside, the air can be kept, maintaining the heat already created.
Additionally, heating is often used as a method to “reduce” humidity, this is due to the fact that relative humidity is temperature dependent, meaning when temperatures rise – relative humidity drops, without removing a single drop of water. So, if you heat to deal with humidity, you may be able to heat much less, or not at all, when using a dehumidifier. Systems such as DryGair even allow you to gain an extra few degrees, if used wisely, by keeping the heat generated by the unit itself, inside the greenhouse.
The insulation of the greenhouse even helps with CO2 enrichment, simply by keeping the CO2 produced by the plants overnight indoors.
A Healthier Agriculture Sector
Coal burning is a perfect example, encapsulating the change agriculture is undergoing. Like many other traditional manufacturing sectors, it is witnessing a transition period, from wasteful, inefficient methods used for decades due to their low price and easy operation, to a highly technological, more efficient, sustainable, and holistic state of mind.
Heating is only a small part of this change, but when all parts are eventually pieced together, we will see a much more efficient model for growing our food.