Hidden champions of botany
Natural gold diggers
Phytomining: Natural gold diggers
- Metal mining by means of plants
- Eco-friendly and low-cost
- Research still in its infancy
Plants as miners clawing raw materials from the Earth: Phytomining is the name of this field of research that’s based on the discoveries of British botanist Alan Baker and U.S. research agronomist Rufus Chaney four decades ago. While having been largely uneconomical so far, phytomining using so-called hyperaccumulator plants has literally begun to sprout again lately due to heavy raw material price increases.
- 100 kg nickel from 500 kg ash
- Economical at 0.1% and higher concentration in the soil
- Profitability of conventional mining starts only at 1% concentration
One of these floral miners is Alyssum murale. The “weed” is grown on fields, harvested and dried, for instance around Lake Ohrid in Albania that’s severely contaminated by heavy metals. By burning the residues of the plants, 500 kilos of the ash can yield 100 kilos of valuable nickel that’s needed for rechargeable batteries and paints for example. Although the yield from deep mining is much greater, biomining is a lot more eco-friendly.
- 25% nickel content in the sap
- Grows only in New Caledonia
- One of 65 nickel-hyperaccumulating species in New Caledonia
Another nickel digger is Pycnandra acuminata, a tree that grows on New Caledonia’s main island. A fourth of its sap consists of nickel.
- Very high energy content for biogas
- 3 mg germanium from 1 kg plant
- Specially bred strains are supposed to multiply the current yield
The “harvesting of metals” such as cobalt, tellurium, thallium and rare-earth elements by now includes the systematic breeding of special plant species. One of these experts is Phalaris arundinacea (aka reed canary grass) whose roots go down as far as 3.5 meters into the ground. It specializes in the semimetal germanium, which is required for fiber optic cables, infrared sensors, chips and solar cells. Specially bred strains are supposed to multiply the current yield.
- 57 g pure gold from 1,000 kg plant ash
- Gold nanoparticles for high-tech industries
- So far only in laboratories
For centuries, scientists have been trying to make gold by artificial means or to convert other metals into gold using chemical processes -- without success so far. Now, phytomining comes into play: Plants are supposed to serve as gold diggers. The noble metal can be extracted from the mustard plant, albeit in such tiny amounts that it’s not profitable.
Green poison aspirators
Phytoremdiation: Green poison aspirators
- Plants extract contaminants from the soil
- More than 500 known plant species
- Re-cultivation of contaminated industrial soil
Cadmium, lead, zinc, nickel, platinum or palladium – around the world, countless areas are contaminated by toxic metals from industrial and military operations or farming. In Germany alone, there are 300,000 such areas. Soil cleanups cost enormous amounts of money. Maltreated Mother Nature herself, though, provides a remedy: plants that “suck” contaminants from the soil – referred to as phytoremediation in professional jargon. However, this form of decontamination is a slow process that takes years. Therefore, the objective is to breed plants with large leaves that suck larger amounts of contaminants from the soil to make it usable again in less time.
- Decontamination of agricultural soil
- Cadmium, lead, zinc, nickel, copper
- Ash contains up to 20% metals
Arabidopsis halleri can absorb high concentrations of heavy metals that would be highly toxic to humans and animals. In this way, it protects itself against herbivores. Arabidopsis halleri thrives on the perimeters of shut-down mines, old steel mills and abandoned industrial areas.
Common water hyacinth
- Deposits arsenic in its roots
- Purifies drinking water by extracting arsenic
- Usable as a living plant or powder
Even aquatic plants may be used for phytoremediation. The common water hyacinth, originally an invasive species introduced from South America, absorbs toxic substances in water and purifies drinking water by extracting arsenic, for example. Research scientists have found that powder from the dried roots of just one common water hyacinth plant is sufficient to filter out arsenic from water.
- Grows very fast
- Usable against cadmium, lead, nickel, copper and zinc
- High energy content: 20 metric tons equate to 6,400 liters of heating oil
The fast-growing edible plant with its potato-like tubers even thrives on barren soil. Its origins are in North and South America. The Jerusalem artichoke absorbs large quantities of various heavy metals in its roots, sprouts and tubers. In addition, the plant is suitable for producing bioethanol.
Filtration: Air cleaners
- Air cleaning by means of plants
- They filter up to 95 % of harmful substances from the air
- such as formaldehyde, benzene, nicotine, trichloroethylene, etc.
That plants make for a pleasant and comfortable atmosphere is a well-known fact. However, they can do a lot more than just look pretty: They store fine dust particles and gases like CO2 and nitrogen that are harmful to climate and health and transform them into oxygen by means of photosynthesis.
- Binds hydrogen, CO2, fine dust particulate, etc.
- Temperature-independent from –30 to +70 degrees C
- Is regarded as a means of storing and controlling water
In our own gardens or yards, it’s typically very unpopular and hard to get rid of. But moss can actively help protect the environment. Since moss has no roots, the plant extracts its nutrients from the air. They include nitrogen, carbon dioxide, fine dust particles and other emission components. In the Sion electric car from Sono, moss is supposed to serve as an air filter for the interior. The idea: Due to the negative charging of the moss, positively charged particulate is filtered out of the air. Microfiber cloths, by the way, work according to a similar principle.
- Was investigated by NASA as an air filter in space stations
- House plant, not hardy
- Also eliminates toxic substances like xylolene and toluene in the air
The green lily that has its origins in South Africa filters up to 95 percent of pollutants from the air, according to a NASA study. Enzymes in the leaves decompose formaldehyde, benzene, carbon monoxide and other substances into harmless ones. Like moss, the plant controls humidity.
- High filtering performance of up to 94 %
- Including benzene and trichloroethylene, mold and mildew
- As a climbing or ground-cover plant
Ivy is another very effective air filter. It fishes 94 % of pollutants from the air, according to the NASA study. As a house plant, ivy is particularly effective against mold and mildew. The plant is able to extract 80 percent of all mold and mildew spores from the room air within twelve hours.
Energy & decontamination
Energy & decontamination: Multi-talent algae
- Used to store energy
- Basis for biofuels
- Transformation of radioactive substances
Algae are a fascinating form of life. Like plants, they use photosynthesis to live, but achieve the conversion much faster which results in near-explosive growth. Algae can be used for biofuels, bioasphalt and as bioreactors for hot water and for heating buildings. At the same time, they serve to extract radionuclides such as radioactive silver, cesium, zinc, cobalt and uranium from the soil.
- Microalgae reproduce by means of radioactive isotopes
- Absorb and store radioactive particles
- Can survive 4,000 times higher radiation dose than humans
In tests of a holding basin for spent nuclear fuel, single-celled microalgae fed on radioactive isotopes, so to speak. The result: The plant purifies the radioactive cooling water. To do so, it absorbs and stores radioactive particles. Thus, the algae survive an absorbed dose of 20,000 Gy. For comparison: A dose of five GY is enough to kill a human being. Scientists are planning to use the algae to clean up contaminated areas such as those in Fukushima and Chernobyl and make them habitable again.
- Largely carbon-neutral fuels
- Fast re-growth
- Technologies not sufficiently investigated yet
Algae may be used as biofuel by means of various technologies. Some algae species can be used to produce oil, which can be transformed into a fuel comparable to diesel by means of ester interchange. Alternatively, the carbohydrates, which account for a large part of the algae mass, are transformed by fermentation into ethanol or, in gaseous form, into methane and carbon dioxide. The production of hydrogen is possible as well.
- Transformation of climate-killing CO2 into energy
- Requires only minimal space and care
- Currently still in test stage
In special bioreactors, the single-celled organisms with a size of three to five micrometers reproduce very fast and are able to produce large amounts of energy in the form of biomass and heat. To do so, they merely require sunlight and CO2. The heat is directly available for hot water and heating, while synthetic gas and subsequently methane can be produced from the algae biomass.
Food: Hunger fighters
- World population keeps growing
- Water is becoming scarce
- Depletion of soils
The world community is facing a humongous challenge: By 2050, it has to produce nearly twice as much food as today – without additional resources. Quite the opposite is true: Water resources are becoming increasingly scarce and desertification is rapidly progressing due to global warming and deforestation. Therefore, the agricultural industry is looking for alternatives to corn and company.
- Undemanding plant, grows at elevations of up to 4,200 meters
- Rich in protein, potassium, phosphor, magnesium and vitamin B1
- Contains all nine essential amino acids
Quinoa, a pseudocereal plant from the Andes that has been cultivated for thousands of years, might be a serious alternative to corn. It grows under extremely adverse conditions, needs only little water and is able to cope with barren soils, which even makes it more resistant than corn. The plant contains plenty of protein and unsaturated fatty acids, as well as vitamins B and E, calcium, magnesium, iron and zinc.
- Deep roots that loosen the soil
- Require no fertilizer, absorb nitrogen from the air
- High protein content of 40 %
Used as a substitute for soy beans. Lupines contain more protein than soy beans, only one third of their carbohydrates and oil, but more than three times as much dietary fiber. Thriving also in Central and Northern Europe, there is no need for long shipping routes, like in the case of soy beans coming from Asia or South America.
- High content of unsaturated fatty acids and amino acids
- Supply vitamin K, copper, iron and magnesium
- Undemanding plant in terms of soil and water
The chick pea is a high-nutrient legume that was cultivated in Asia Minor as far back as 8,000 years ago. It is able to cope with barren soils and needs little water, but requires sub-tropical heat. It is mainly cultivated in Australia and India.
Professor Ute Krämer
Professor Ute Krämer, born in 1969, has been teaching at Ruhr University of Bochum since 2009. She specializes in molecular genetics and plant physiology. Her work is focused on the development of an integrative molecular-functional understanding of the interaction of plants with their environment. In this context, she investigates both the acclimatization of plants to their dynamic environment and the evolutionary adjustment within plants on a molecular level.