Hemp, or industrial hemp, is a variety of the Cannabis sativa plant species that is grown specifically for industrial use. It can be used to make a wide range of products. Along with bamboo, hemp is one of the fastest growing plants on Earth. It was also one of the first plants to be spun into usable fibre 50,000 years ago. It can be refined into a variety of commercial items, including paper, rope, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed. 

Although cannabis as a drug and industrial hemp both derive from the species Cannabis sativa and contain the psychoactive component tetrahydrocannabinol (THC), they are distinct strains with unique phytochemical compositions and uses. Hemp has lower concentrations of THC and may have higher concentrations of cannabidiol (CBD), which decreases or eliminates its psychoactive effects. The legality of industrial hemp varies widely between countries. Some governments regulate the concentration of THC and permit only hemp that is bred with an especially low THC content.

Uses of Hemp

Hemp is used to make a variety of commercial and industrial products, including rope, textiles, clothing, shoes, food, paper, bioplastics, insulation, and biofuel. The bast fibres can be used to make textiles that are 100% hemp, but they are commonly blended with other fibres, such as flax, cotton or silk, as well as virgin and recycled polyester, to make woven fabrics for apparel and furnishings. The inner two fibres of the plant are woodier and typically have industrial applications, such as mulch, animal bedding, and litter. When oxidized (often erroneously referred to as “drying”), hemp oil from the seeds becomes solid and can be used in the manufacture of oil-based paints, in creams as a moisturizing agent, for cooking, and in plastics. Hemp seeds have been used in bird feed mix as well. A survey in 2003 showed that more than 95% of hemp seed sold in the European Union was used in animal and bird feed.

Food

Hemp seeds are high in complete protein and a great source of iron. They can be eaten raw, ground into hemp meal, sprouted or made into dried sprout powder. Hemp seeds can also be made into a liquid and used for baking or for beverages such as hemp milk and tisanes. Hemp oil is cold-pressed from the seed and is high in unsaturated fatty acids. The leaves of the hemp plant, while not as nutritional as the seeds, are edible and can be consumed raw as leafy vegetables in salads and pressed to make juice.
In 2011, the US imported $11.5 million worth of hemp products, mostly driven by growth in the demand for hemp seed and hemp oil for use as ingredients in foods such as granola.
In the UK, the Department for Environment, Food and Rural Affairs treats hemp as a purely non-food crop, but with proper licensing and proof of less than 0.2% THC concentration, hemp seeds can be imported for sowing or for sale as a food or food ingredient.

Nutrition

A 100-gram portion of hulled hemp seeds supplies 586 calories. They contain 5% water, 5% carbohydrates, 49% total fat, and 31% protein. Hemp seeds are notable in providing 64% of the Daily Value (DV) of protein per 100-gram serving. Hemp seeds are a rich source of dietary fibre (20% DV), B vitamins, and the dietary minerals manganese (362% DV), phosphorus (236% DV), magnesium (197% DV), zinc (104% DV), and iron (61% DV). About 73% of the energy in hemp seeds is in the form of fats and essential fatty acids, mainly polyunsaturated fatty acids, linoleic, oleic, and alpha-linolenic acids. The ratio of the 38.100 grams of polyunsaturated fats per 100 grams is 9.301 grams of omega-3 to 28.698 grams of omega-6. Typically, the portion suggested on packages for an adult is 30 grams, approximately three tablespoons.
Hemp seeds’ amino acid profile is comparable to other sources of protein such as meat, milk, eggs, and soy. Protein digestibility-corrected amino acid scores (PDCAAS), which attempt to measure the degree to which a food for humans is a “complete protein”, were 0.49–0.53 for whole hemp seed, 0.46–0.51 for hemp seed meal, and 0.63–0.66 for hulled hemp seed.

Fibre

Hemp fibre has been used extensively throughout history, with production climaxing soon after being introduced to the New World. For centuries, items ranging from rope, to fabrics, to industrial materials were made from hemp fibre. Hemp was also commonly used to make sail canvas. The word “canvas” is derived from the word cannabis. Pure hemp has a texture like linen. Because of its versatility for use in a variety of products, today hemp is used in a number of consumer goods, including clothing, shoes, accessories, dog collars, and home wares. For clothing, in some instances, hemp is mixed with lyocell.

Building material

Concrete-like blocks made with hemp and lime have been used as an insulating material for construction. Such blocks are not strong enough to be used for structural elements; they must be supported by a brick, wood, or steel frame. However, hemp fibres have been shown to be usable as a replacement for wood for many jobs, including creating durable and breathable homes. The most common use of hemp lime in building is by casting the hemp and lime mix while wet around a timber frame with temporary shuttering and tamping the mix to form a firm mass; after the removal of the temporary shuttering, the solidified hemp mix is then ready to be plastered with a lime plaster.

The first example of the use of hempcrete was in 1986 in France with the renovation of the Maison de la Turquie in Nogent-sur-Seine by the innovator Charles Rasetti. In the UK hemp lime was first used in 2000 for the construction of two test dwellings in Haverhill. Designed by Modece Architects, who pioneered hemp’s use in UK construction, the hemp houses were monitored in comparison with other standard dwellings by BRE. Completed in 2009, the Renewable House is one of the most technologically advanced made from hemp-based materials. The first US home-made of hemp-based materials was completed in August 2010 in Asheville, North Carolina.

A panel system of hemp-lime panels for use in building construction is currently under test in a European Union-funded research collaboration led by the University of Bath. The panels are being designed to assure high-quality construction, rapid on-site erection, optimal hygrothermal performance from day one, and energy- and resource-efficient buildings. The 36-month work program aims to refine product and manufacturing protocols and produce data for certification and marketing, warranty, insurance cover, and availability of finance. It also includes the development of markets in Britain, France, and Spain.

Hemp is used as an internal plaster and is a mixture of hemp shive mixed with larger proportions of a lime-based binder. Hemp plaster has insulative qualities.

Plastic and composite materials

A mixture of fiberglass, hemp fibre, kenaf, and flax has been used since 2002 to make composite panels for automobiles. The choice of which bast fibre to use is primarily based on cost and availability. Various car makers are beginning to use hemp in their cars, including Audi, BMW, Ford, GM, Chrysler, Honda, Iveco, Lotus, Mercedes, Mitsubishi, Porsche, Saturn, Volkswagen, and Volvo. For example, the Lotus Eco Elise and the Mercedes C-Class both contain hemp (up to 20 kg in each car in the case of the latter)

Paper

Hemp paper are paper varieties consisting exclusively or to a large extent from pulp obtained from fibres of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp offers four to five times longer fibre, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. However, production costs are about four times higher than for paper from wood, since the infrastructure for using hemp is underdeveloped. If the paper industry were to switch from wood to hemp for sourcing its cellulose fibres, the following benefits could be utilized:

• Hemp yields three to four times more usable fibre per hectare per annum than forests, and hemp does not need pesticides or herbicides.
• Hemp has a much faster crop yield. It takes about 3-4 months for hemp stalks to reach maturity, while trees can take between 20 to 80 years. Not only does hemp grow at a faster rate, but it also contains a high level of cellulose. This quick return means that paper can be produced at a faster rate if hemp were used in place of wood.
• Hemp paper does not require the use of toxic bleaching or as many chemicals as wood pulp because it can be whitened with hydrogen peroxide. This means using hemp instead of wood for paper would end the practice of poisoning Earth’s waterways with chlorine or dioxins from wood paper manufacturing.
• Hemp paper can be recycled up to 8 times, compared to just 3 times for paper made from wood pulp.
• Compared to its wood pulp counterpart, paper from hemp fibres resists decomposition and does not yellow or brown with age. It is also one of the strongest natural fibres in the world – one of the reasons for its longevity and durability.
• Several factors favour the increased use of wood substitutes for paper, especially agricultural fibres such as hemp. Deforestation, particularly the destruction of old growth forests, and the world’s decreasing supply of wild timber resources are today major ecological concerns. Hemp’s use as a wood substitute will contribute to preserving biodiversity.

However, hemp has had a hard time competing with paper from trees or recycled newsprint. Only the outer part of the stem consists mainly of fibres which are suitable to produce paper. Numerous attempts have been made to develop machines that efficiently and inexpensively separate useful fibres from less useful fibres, but none have been completely successful. This has meant that paper from hemp is still expensive compared to paper from trees.

Jewellery

Hemp jewellery is the product of knotting hemp twine through the practice of macramé. Hemp jewellery includes bracelets, necklaces, anklets, rings, watches, and other adornments. Some jewellery features beads made from crystals, glass, stone, wood and bones. The hemp twine varies in thickness and comes in a variety of colours. There are many different stitches used to create hemp jewellery, however, the half knot and full knot stitches are most common.

Cordage

Hemp rope was used in the age of sailing ships, though the rope had to be protected by tarring, since hemp rope has a propensity for breaking from rot, as the capillary effect of the rope-woven fibres tended to hold liquid at the interior, while seeming dry from the outside. Tarring was a labour-intensive process, and earned sailors the nickname “Jack Tar”. Hemp rope was phased out when manila rope, which does not require tarring, became widely available. Manila is sometimes referred to as Manila hemp but is not related to hemp; it is abaca, a species of banana.

Water and soil purification

Hemp can be used as a “mop crop” to clear impurities out of wastewater, such as sewage effluent, excessive phosphorus from chicken litter, or other unwanted substances or chemicals. Additionally, hemp is being used to clean contaminants at the Chernobyl nuclear disaster site, by way of a process which is known as phytoremediation—the process of clearing radioisotopes and a variety of other toxins from the soil, water, and air.

Weed control

Hemp crops are tall, have thick foliage, and can be planted densely, and thus can be grown as a smother crop to kill tough weeds. Using hemp this way can help farmers avoid the use of herbicides, gain organic certification, and gain the benefits of crop rotation. However, due to the plant’s rapid and dense growth characteristics, some jurisdictions consider hemp a prohibited and noxious weed, much like Scotch Broom.

Biofuels

Biodiesel can be made from the oils in hemp seeds and stalks; this product is sometimes called “hempoline”. Alcohol fuel (ethanol or, less commonly, methanol) can be made by fermenting the whole plant.
Filtered hemp oil can be used directly to power diesel engines. In 1892, Rudolf Diesel invented the diesel engine, which he intended to power “by a variety of fuels, especially vegetable and seed oils, which earlier were used for oil lamps, i.e., the Argand lamp.”
Production of vehicle fuel from hemp is ridiculously small. Commercial biodiesel and biogas are typically produced from cereals, coconuts, palm seeds, and cheaper raw materials like garbage, wastewater, dead plant and animal material, animal faeces and kitchen waste.