Simple measures strongly reduce energy consumption in bulb storage
A considerable reduction of electricity and gas consumption in bulb storage can be achieved with simple tricks and an advanced device. This is shown in research by Applied Plant Research.
Bulb storage requires a lot of energy; this energy is required to maintain a good quality: temperature must remain constant and air needs to be refreshed regularly. And yet, savings are possible.
Standard advice for ventilation
The scientists of PPO started by looking at ventilation. Of course, growers do not want to run the risk of quality loss of their bulbs.
Ethylene formation is one of the major problems during storage. This gas is formed by ‘acid’ bulbs, these are bulbs infested by the Fusarium fungus. When the ethylene concentration in the storage cell is getting too high, the main tulip bulbs start to form several small bulbs (‘verklistering’). This means a great loss to the farmer whose income depends on selling the largest possible bulbs.
Ventilation
Bulb growers try to prevent ‘verklistering’ by regular ventilation. This keeps the ethylene concentration low. Growers are therefore burning so much gas that they are certain that ethylene gas production remains below a maximum level. Here they follow the standard advice for ventilation; this is based on the assumption that a batch contains no more than 5 per cent acid bulbs. Fact is that the gas itself can neither be seen nor smelled.
Device measures ethylene

Together with a technical company the researchers have developed a device for measuring low ethylene concentrations. This device can be connected to the climate computer which only opens the ventilation valves when the concentration exceeds a certain value. This restricts ventilation to a minimum. This results in growers - on average - saving some 70 per cent of their gas consumption. But of course growers need to have confidence in the system.
Less electricity
But not only savings on gas are possible; electricity consumption can be reduced as well. The ventilator blowing air through the crates takes more energy than necessary because it is set such that the layer of crates that gets the smallest amount of air (usually the second layer from the top) is still getting sufficient air.
The researchers developed a method for measuring the amount of air passing through the complete stack of crates. Air distribution through the crates can then easily be improved by simple means such as triangular slats or a scoop that bends the air flow. This means that the ventilator needs to make fewer revolutions, up to 20 per cent. This results in an energy saving of almost 50 per cent, since (energy consumption of the ventilator is proportional to the revolutions per minute to the 3rd power).
Suitable for all bulb growersResults on a number of enterprises show that improvement of any system is possible. Energy use can be lowered to 85 per cent.