Category Archives: CO2

Measuring CO2 in a Greenhouse

CO2 in Greenhouses in General

CO2 is one of the key ingredients of photosynthesis, meaning it is essential for plants to grow. Monitoring CO2 in a greenhouse allows optimisation of plant growth conditions, resulting in more efficient plant growth and higher crop yield. Different plants need different levels of CO2 in the air to maximise development.

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Facts & Figures

One of the largest greenhouses in the world is in Almeria, Spain where greenhouses cover almost 50000 acres (200km2)

In the Netherlands, greenhouses occupy 0.25% of the total land area.

The Netherlands has around 9000 greenhouse enterprises that operate over 10000 hectares of greenhouses and employ some 150000 workers: 80% of the manufactured produce is exported.

Why The Need to Measure CO2

It is essential to monitor CO2 levels at all times because different plants have different needs regarding CO2. Before photosynthesis, CO2 is collected by the enzyme RuBisCO. However, RuBisCO is just as happy to collect O2 as it is CO2. In C3 plants, RuBisCO collects CO2 from the air as soon as it comes through the stomata on the leaf. This means that if levels of CO2 in the air are low compared to levels of O2, the RuBisCO will just collect more O2 and the plant growth will be less efficient. In a C4 plant, there is an extra step during which CO2 is ‘filtered’ from the air and passed on to the RuBisCO. During this extra step, CO2 can be stored, meaning the stomata do not need to be open all of the time, helping to prevent water loss. In the C3 plant, the stomata need to be open more as there is not such storage of CO2. A third kind of plant, a CAM plant, can only collect CO2 at night, as its stomata are closed during the day.

Tomato_leaf_stomate_1-colorStomata on a tomato leaf

It is important to have close control of the ventilation of a greenhouse to utilise CO2 to maximum effect without risk
of damaging plants. Generally, the best practice is to provide increased CO2 to young plants and parent plants regularly, and to all other plants for a short period during spring. If the plant is sensitive it is extremely important to have pure CO2, to prevent damage. Up to 1 000 ppm CO2 is estimated as a good level.

If the levels of CO2 are too high in the greenhouse, plants can be damaged. If CO2 levels rise too high, plants will close their stomata to protect themselves, resulting in less transpiration, and therefore less nutrition is drawn through the plant, slowing down growth. CO2 levels vary considerably over a 24 hour period. This is because during the night, plants can stop photosynthesis (in the absence of light) and begin respiring. this means plants will switch from using CO2 to producing CO2.

plantsWhen there is plenty of light, a plant will photosynthesize, but when light levels are too low plants will begin to respire instead

What is the Result?

If all plants of a crop are grown in the same conditions (including CO2 levels), the chance that all plants will be ready for harvest at the same time is increased. The annual consumption of CO2 in a greenhouse is generally about 5-10 kg/m2, only in exceptional cases does would it be higher. The effect, of using CO2, on profit varies considderably. For example, tomatoes and cucumbers can give 8-10% higher return when growin in optimal CO2 levels. Plants grown in a CO2 enriched environment generally produce greater biomass than other plants, particularly in the roots, allowing faster growth and resulting in stronger plants with an increased reproductive rate.

Philip Robinson                                                                                                       Rotronic UK

CO2 and Indoor Air Quality (IAQ)

Indoor Air Quality in General

The quality of the air in a room can greatly affect the health, productivity, and well being of any occupants. Previously the temperature and humidity of indoor air were considered as the most important parameters contributing to air quality, but there are several other factors which must be taken into account.

Indoor Air Quality (IAQ) problems are very often caused by gases or particles released into the air by pollution sources. This can be avoided by carefully selecting the materials which are to be used inside dwellings, offices, classrooms, gymnasiums, hotels, shopping malls, hospitals and in all en-closed spaces which are inhabited. But there is another source of air pollution, which cannot be avoided. this other source is people themselves. Every time a person exhales, CO2 is released. Inadequate ventilation may increase CO2 concentration to an unhealthy or even life-threatening level.

carbon_dioxide_3d_ball

CO2: made up of 2 oxygen atoms, double bonded to a single carbon atom.

The most important control parameters for a good Indoor Air Quality are temperature, relative humidity and CO2 concentration. If these values are used with an intelligent air conditioning system, an energy efficient air supply can be used to produce a high quality atmosphere.

Facts & figures:

CO2 is a naturally occurring molecule consisting of two oxygen atoms and a single carbon atom.

At standard temperature and pressure CO2 is a gas, invisible and without any smell or taste.

CO2 is 50% heavier than air and has no liquid state under atmospheric pressure.

In the earth’s atmosphere CO2 has a concentration of 390 ppm by volume.

The worldwide industry produces approximately 36 billion tons of CO2 per year.

Industrial activities are responsible for an increase of atmospheric CO2 concentration and thus for an increase of global warming (greenhouse effect).

Influence of CO2 on Humans

Only a small amount of the atmosphere is made up of CO2, the prevailing components are nitrogen and oxygen. The natural outdoor atmosphere CO2 level is approx. 390 ppm. Increasing this concentration causes several symptoms of poisoning, ranging from drowsiness at around 1´000ppm to unconsciousness and even death at above 10´000 ppm. Even if a  rise in CO2 concentration has not yet severely influenced the health of people, it may reduce their productivity, efficiency and well-being.

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Some of the possible health effects

How to Measure CO2

The most common measuring method for CO2 concentration nowadays is based on a spectroscopic principle. Sending infrared light (IR) with a wave length of 4.23 μm through a gas sample. CO2 molecules in the sample absorb the light at this wavelength. an IR sensor is then used to detect any changes in the energy levels of the light after passing through the sample. The more C)2 in the sample, the more of the light that will be absorbed, and the weaker the IR signal will be when it reaches the sensor.

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Example of an IR CO2 sensor

The sensitivity of a CO2 sensor increases with the length of the light path through the sample gas. Thus the sensor used in Rotronic CO2 measuring devices makes use of multiple reflections of the IR beam on the walls of the probe chamber. this means the small CO2 sensor (2.5 cm x 5 cm) has a measuring path length of 12.5 cm and is accordingly sensitive. This type of sensor is called a NDIR (Non Dispersive Infra Red) sensor. This means that a broadband IR light source is used and the measured wavelength is filtered out at the end of the beam in front of the IR detector.

Why the Need to Measure CO2

New energy efficient demands lead to more airtight buildings and ventilation being completely turned off at night. Intelligent HVAC systems must be able to adapt themselves to situations with changing occupants of rooms. One answer is Demand Controlled Ventilation (DCV) with built-in CO2 sensors. By using DCV, huge amounts of energy can be saved without any drawback for the occupants. According to a study of the UN Climate Panel 40-50% of world energy is used in buildings. Only the adoption of the EU Directive on Energy Efficient Buildings would result in saving 30-45 MT of CO2/year. As HVAC (Heating, Ventilation and Air Conditioning) is responsible 40-65% of energy usage in commercial and public buildings, a balance between comfort and energy saving must be found.

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A large HVAC system

One example demonstrates the evidence of CO2 controlled room ventilation. The exhaled air of a human contains up to 40´000 ppm CO2. In one hour a person breathes out 15 litres of CO2. Thus in a classroom with a volume of 200 m³ occupied by 25 pupils the CO2 concentration increases in one hour by 1´875 ppm!

Especially in wine cellars, breweries, the beverage industry and other industries in which CO2 may be produced or processed the constant measuring of CO2 concentration is absolutely vital to prevent a deadly threat to the employees. This is not only a rational procedure but is also enforced by official regulations in nearly every developed country.

Philip Robinson                                                                                                       Rotronic UK

Chicken Hatcheries.

As it is nearly Easter, I thought it would be a good idea post something related to eggs, unfortunately not the chocolate kind…

Chicken hatcheries in general

It takes about 21 days to hatch a chicken and during that time, it is crucial that the surroundings are controlled for it to be successful. Egg hatching farms transform the chickens into “broilers” or egg laying hens. Meat from egg hatching farms is the most consumed worldwide.

Facts & figures:

Approximately 49 billion chickens are consumed worldwide every year. That is 134 million every day.

Chicken is the most common type of poultry in the world.

100g of baked chicken breast contains 4 grams of fat and 31 grams of protein.

Sustainability of chicken meat increases by 20%, when using CO2 for modified atmosphere processing.

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Why the need to measure CO2?

Less staff required to run the breeding stations thanks to all hatching happening at around the same time. This means it is easier to plan shipments and know how many birds can be transported at a time. This results in less capital and reduced transport costs.

A smaller number of birds die during transportation, which results in more profit per shipment and less feed losses.

More efficient and cheaper feeding options, both through feed reduction and reduction in time.

Chickens_eating

Faster and easier to slaughter the animals using CO2, and there is no unnecessary suffering to the birds.

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Packing using CO2, means food will last longer in supermarkets and for customers once purchased. This means a reduction in food waste from expired food.

How does it work?

The fertilized eggs are placed in a chamber, in which CO2 levels are controlled, depending on what stage of development the eggs are in. Living eggs contribute to the levels of CO2 (not 100% of all eggs are alive), which means that you have to monitor the CO2 continuously.

It has been shown that during embryonic development, the supply of CO2 has positive effects on the health of the organism after birth. Control of CO2 in chickens in development has also led to a more controlled hatching time.

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Once CO2 levels insid an egg reach a certain level, the fully developed chickens start to hatch. When the chick has hatched, oxygen will be supplied. Once the eggs are hatched, they are sent off in trucks where the birds continue to develop during the transportation. To ensure the good health of the chicks during their transportation, the CO2 levels in the truck are controlled for the whole journey.

It has been found that a bird’s metabolism works slower at high concentrations of CO2. Controlling CO2 levels therefore means it can take less time and less food to raise broilers or egg laying hens. This means production will be cheaper for the companies, it´s also more sustainable to use less feed per pound of chicken.

The chickens are slaughtered after being knocked out with high levels of CO2, which only take a few seconds. This method is more humane than killing by electrical stunning.

Philip Robinson                                                                                                       Rotronic UK

Greenhouses and environmental control

The idea of growing plants in environmentally controlled areas has existed since Roman times. The emperor Tiberius ate a cucumber-like vegetable daily. The Roman gardeners used artificial methods (similar to the greenhouse system) of growing to have the vegetable available on his table every day of the year.

The next step from the conventional greenhouse as we know it today will be the introduction of “vertical farms”. Currently, sophisticated so called “plantscrapers“ are being planned or are already under construction in Sweden, Japan, China, Singapore and the United States.

Skyscraper

Skyscraper farming might yet be a possible answer to the question of how to feed the nine billion people that are expected by the middle of the century. These types of green-houses have a tightly con-trolled level of temperature, humidity & CO2, sophisticated watering systems and in addition to sunlight, advanced artificial LED lighting that is specifically designed and installed for each plant family. This way, the crops grow much faster and very efficiently all year round. It is estimated, that the Swedish plantscraper that is planned to be 54m high, will produce thousands of tonnes of food a year, enough to feed up to 30,000 people.

Facts & figures:

  • Tomato is the second most important commercial vegetable crop after potato. Current world production is about 100 million tonnes produced on 3.7 million hectares.
  • In the year 2000, per capita consumption of fresh tomatoes in the U.S. was 17.8 lb,/ 8.73 kg.
  • About 85 percent of the world’s soybeans are processed, or “crushed,” annually into soybean meal and oil. Around 98 percent of the soybean meal that is crushed is further processed into animal feed.
  • The Food and Agriculture Organization of the United Nations (FAO) reports that world production of carrots and turnips (these plants are combined by the FAO for reporting purposes) for calendar year 2011 was almost 35,658 million tonnes.

Why do we need to measure humidity?

Greenhouse humidity levels are important both in prevent-ing plant diseases and promot-ing healthy and strong plant growth. High humidity can promote Botrytis and other fungal diseases. High humidity also restricts plant transpira-tion, which in turn limits evapo-rative leaf cooling and can lead to overheating of plant foliage. If high humidity persists for a long time, the restriction of transpiration can limit the “transpiration stream” of nutrients and can lead to nutrient deficiencies.

Low humidity levels are best avoided because these may increase foliar transpiration to the extent that the root system cannot keep up. Humidity is perhaps the most difficult of the greenhouse conditions to control. Most growers simply aim to avoid the extremes of humidity. Over most temperature ranges, a greenhouse humidity of 50 – 85 %rh is generally safe. Low humidity can be managed with the use of misters and foggers. It is also useful to shade plants under conditions of low humidity to reduce the rate of transpiration.

Transpiring plants add water vapour to the greenhouse air, increasing the humidity inside the greenhouse. Therefore, managing high humidity starts with ventilation control. Replacing warmer, humid greenhouse air with cooler, drier external air. Ventilation also involves significant energy losses, and therefore ventilation must often be accompanied by heating. Therefore, lowering greenhouse humidity with a combination of ventilation and heating increases energy costs significantly.

Candice 
Area Sales Manager

Rotronic International Sales Meeting 2014 Grindelwald Photo Gallery

Great to see everyone at the 2014 ISM in Grindelwald!

A look at the Beer Brewing Process – Just in time for the Rotronic 2014 International Sales Meeting

Beer brewing in general

There is no exact date, as to when the first beer was brewed but already at the beginning of the fifth millennium BC, people in southern Mesopotamia, in a region known as Sumer (modern Iraq), were brewing beer.

Beer, like other commodities such as wheat and other grains, was used as a currency. A clay tablet, dating from 6’000 BC contains one of the oldest known beer recipes.

Beer Map
Beer consumption throughout the world

The basic ingredients of beer are: water; a starch source: which is able to be fermented; yeast: to produce the fermentation; a flavouring such as hops. Yeast is the microorganism that is responsible for fermentation. Specifically Saccharomyces cerevisiae is the species of yeast that is used for brewing.

Facts & figures:
Beer is the third most popular beverage in the world, coming in directly behind tea and water.
American beer is made mostly from rice. This was invented to give American beer a lighter taste and tap into the market of women buyers.
In the UK 28 million pints of beer are consumed every day, which equates to 100 litres per head each year.
Belgium has over 400 different beer brands.
Cenosillicaphobia is the fear of an empty glass.

There are several steps in the brewing process, which include malting, milling, mashing, lautering, boiling, whirl-pooling, fermenting, conditioning, and filtering.

Step by step brewing:
  • Malting: germination of cereal grains. The sprouted cereal is then kiln dried at around 55°C. Milling: grinding of the malted cereal.
  • Mashing: the cereals are mixed with water and then heated.
  • Lautering: separation of the mash: the liquid (wort) is separated
    from the residual grains.
  • Boiling: the wort is boiled to ensure sterility and then hops are added for flavour!
  • Whirl-pooling: the wort is sent into a whirlpool, removing the dense particles using centrifugal force.
  • Fermenting: yeast is added to the wort: conversion of the carbohydrates to alcohols and carbon dioxide – the chemical conversion of sugars into ethanol!
  • Conditioning: the tank is cooled and the yeast and proteins separate from the beer. This conditioning period is also a maturing period.
  • Filtering: the beer is filtered: stabilising the flavour.
  • Packaging: the beer is packed then to the customers
Example brewing process
Example brewing process
Why the need to measure the carbon dioxide?

Carbon dioxide Carbon dioxide (CO2) is a naturally occurring chemical compound. It is a gas at standard temperature and pressure.

We inhale oxygen and exhale carbon dioxide. The carbon dioxide level in exhaled air is rather constant: around 3,8%. When carbon dioxide is exhaled it will quickly be mixed with the surrounding air even indoors and provided that the ventilation is good, the concentration will be reduced to harmless levels. Indoor carbon dioxide levels usually vary between 400 and 1’200 ppm (parts per million). Outdoor carbon dioxide levels are usually 350 – 450 ppm.

Beer brewing process: Heavily industrialised or contaminated areas may periodically have a higher concentration of CO2. Carbon dioxide is released during the beer brewing process and as you will see below, CO2 is toxic for living organisms. In brewery environments where process generated carbon dioxide is widely present, the maximum permitted carbon dioxide concentration according to most standards is as high as 5’000 ppm (5%) during an 8 hour working period.

Beer storage: Most beer leaves the brewery carbonated: beer and carbon dioxide are sealed in a container under pressure. It can be carbonated during fermentation but it can also be carbonated in the bottle. In this case the beer is allowed to ferment completely. It is left unfiltered which leaves active yeast suspended in it. A small amount of sugar is then added at bottling time. The yeast begins to act on the sugar: CO2 is released and absorbed by the beer.

Beer can also be force carbonated, in which case it is allowed to fully ferment. Then CO2 is pumped into a sealed container with the beer and absorbed by the liquid. In this case, a tank of carbon dioxide will also be required. Undetected leaks in a gas system is a costly waste and a safety risk to personnel. While small leaks are inherent in any gas system, those of significant size raise the level of economic and safety risk.

How does CO2 affect the human body?

Due to the health risks associated with carbon dioxide exposure, there are regulations and laws in place to avoid exposure! The US National Institute for Occupational Safety and Health (NIOSH) states that carbon dioxide concentrations exceeding 4% are immediately dangerous to life and health.

In indoor spaces occupied by people: concentrations higher than 1’000 ppm will cause  discomfort in more than 20% of occupants. At 2’000 ppm, the majority of occupants will feel a significant degree of discomfort and many will develop nausea and headaches.

How CO2 affects the body
How CO2 affects the body

Case study: The lake Nyos
The lake Nyos is a crater lake situated in Cameroon. In 1986, a pocket of magma from under the lake, leaked a large amount of CO2 into the air. The result was suffocation of around 1’700 people and 3’500 livestock!

As we take beer brewing seriously we will be sure to test a number of varieties with our colleagues from the world over at the Rotronic 2014 International Sales meeting in Grindelwald next week!

Dr Jeremy Wingate
Rotronic UK

CO2 Monitoring in the Beverage Industry

The Carbonating Process

Everybody loves a refreshing sparkling drink during the summer heat. CO2 does not only bring the bracing sparkling effect into your drink but even helps to conserve the beverage. A chemical reaction of CO2 and water forms carbonic acid which has an antibacterial effect. All well known soft drinks come with the right fizz.

The beverages are treated with a carbonating process just before the final bottling or canning. Carbonating systems mainly consist of a booster pump, a CO2 saturator, a carbonating tank and an optional CO2 analyser to check the carbon acid content of the final product.

With the aid of a booster pump the beverage mixture is conveyed to the saturator which works according to the Venturi principle. An optimising control keeps the flow velocity through the saturator within a constant working range. This generates a partial vacuum at the smallest cross section of the saturation which causes a reduction of the pressure level. This suction effect then mixes the CO2 with the beverage liquid. The short-time increase of the flow velocity guarantees a fine distribution of the gas and homogenous mixing.

The process essentially depends on the tank pressure which has to be set slightly higher then the saturating pressure of a specific product. Right after that, the drink is ready to be bottled automatically to preserve its texture.

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CO2 saturator in a carbonating stage of a bottling line

Why the need to monitor CO2 in a beverage plant?

Carbonating processes use most of the CO2 in the beverage industry. But beside that the gas also occurs during fermentation or it is used for refrigeration – so CO2 is omnipresent in such facilities.

High concentrations of CO2 in closed areas where workers attend to their jobs can become a lethal risk. Extensive CO2 levels can lead to bad headaches, drowsiness, unconsciousness and even sudden death. A CO2 level above 5000ppm is considered as alarming. The gas can neither be recognised by its odour nor by its visual appearance. Soft-drink factories or breweries therefore require an accurate CO2 control and alarm system to maintain their high standard of operational safety.

Capture

To assure hygienic conditions and to reduce the risks of CO2 incidents, bottling lines which fill carbonated drinks are often operated in separated areas of a factory. There is a controlled loss of CO2 during the bottling or canning process of sparkling drinks which is minimal, but the amount adds up considering that industrial lines are able to fill up to 30.000 bottles an hour. With each filling a tiny amount of CO2 gets exposed to the surrounding atmosphere.

Factories require big amounts of CO2 which is delivered and stored in gas cylinders. During transport or storage there is always the risk of a thin crack occurring and that gas escapes unnoticed. Drinks which are not meant to be carbonized such as beer or wine also emit CO2 during the fermentation process. The gas needs to be release controlled. Also here leakage can be a danger and CO2 sensors help to keep control of the atmosphere.

This small insight shows how beverage manufacturers depend on reliable CO2 monitoring systems!

Candice – Sales Support