The new generation of nature-based carbon removals is here! Hempcrete biogenic carbon capture is a good illustration of how new credits can combine the strengths of both tech and nature removals. Being technically considered a natural resource under the CRCF qualification, they bring about immense ecological co-benefits, as well as are fully renewable and circular while providing permanence and protection against reversals and tech-based credits (DACCS, biochar, BECCS…).
This is much welcome news as there is too much carbon in the atmosphere (billions of tonnes too many). Since the Industrial Revolution, we have emitted more than 2,000 gigatons of CO2. In May 2023, carbon dioxide hit 424 particles per millimetre. To stop climate change, not only do we need to stop emitting CO2, but we need to retract enough of it from the atmospheric pool so we can go back to preindustrial levels (about 300 ppm).
However, according to The 2023 State of Carbon Dioxide Removal report(1), humans still emit about 50 Gt/year of CO2 yearly (let alone other Greenhouse gases (GHGs)). While the total capacity of existing carbon sinks worldwide is only 2Gt/year. Until now, we have managed to permanently store less than 10 Gt from the atmosphere. This is why the priority is to cut as much of our emissions as possible before we try to offset the remaining, incompressible, CO2. Here is how climate change mitigation should go:
De facto, however, not all CO2 emissions can be suppressed. For instance, it will always be necessary to heat buildings in winter while even electric cars have a construction and energy use carbon footprint. Recycling uses energy whose production emits some CO2 - even if the greener sources have a minuscule impact compared to fossil fuels. Once efforts to suppress or reduce emissions have reached their limits, and only then, the remaining emissions can be compensated for by carbon credits.
So let’s focus on offsetting, as this is the main purpose of carbon credits. First things first, a carbon credit is the equivalent of one ton of CO2 that has either been pulled out of the atmosphere (carbon capture) or that was not emitted as a consequence of choosing a greener - also almost systematically more expensive - solution (avoided emissions). More on this later. This blog post aims to show the method used to generate the credits attached to the hempcrete credits that Augur Associates monitors.
The core of the methodology used to generate those credits is a comparative life cycle assessment (LCA). An LCA is an assessment of the environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case of a manufactured product, environmental impacts are assessed from raw material extraction and processing (cradle), through the product's manufacture, distribution and use, to the recycling or final disposal of the materials composing it (grave).
In Europe, all construction materials are subjected to an Environmental Product Declaration (EPD - also called FDES in France). These EDPs are compulsory and require the inclusion of a full product LCA. There are two ways an EPD can generate carbon credits: Captured carbon and Avoided emissions.
Captured carbon
Using the hempcrete LCA, we can see how much CO2 is stored in the hempcrete. This captured carbon is the result of incorporating biomass in the mix: biomass is extracted from plants that grow capturing atmospheric CO2 to fuel their growth in a process called photosynthesis (the process is called biogenic carbon capture). This carbon is durably stocked in the plant and will remain locked if the plant is transformed into a durable and final material - in our case hempcrete, which will remain in use for 100 years(2). In other words, the CO2 pulled out of the atmosphere by the hemp plant will remain in the hempcrete for 100 years before either recycling the hempcrete for a new cycle of storage (minus the CO2 emissions caused by the recycling process) or is decommissioned and left in a landfill.
NB: hempcrete can also be used as compost which allows the transfer of carbon in the soil where it is disposed. The carbon will remain locked in the soil unless it is damaged (ex: tilling).
Avoided emissions
Once hempcrete is produced, biogenic carbon locked, it is deployed on a construction site. In almost all cases, it is used to replace another more carbon-intensive construction material - say, concrete. To keep this example, concrete emits about 200 kg of CO2 per m3(3) while hempcrete’s emissions are negative or close to 0. It is possible to measure the difference in emissions and turn it into avoidance credits. While less valuable (they do not contribute to reducing the overabundance of CO2 in the atmosphere) they can be used to fund less polluting solutions, allowing us to transition towards a greener economy.
To calculate avoided emissions, hempcrete’s footprint must be confronted with the emissions of the product it replaces (also called the baseline scenario; here, concrete). Both of those values are covered by the LCA present in each product’s EPD. The difference between both emissions scenarios is then converted into avoidance credits.
Both captured carbon and avoided emissions are covered in Augur Associates’ hempcrete projects. Credits are differentiated and sold separately, at a different price, so buyers know exactly what they are contributing to with their purchase. Those credits are fully transparent and can be traced back to the specific construction site and when the hempcrete has been used.
Both are also retrospective credits, in that they are based on an actual tangible tonnage of final materials that are counted at the end of every year and converted into credits. In other words, we can finely assess the carbon captured. In the past, credits were mostly prospective – they were based on an estimated carbon captured, for instance, within trees, which are reputed to live for 60-odd years, with limited accountability for risks they are exposed to during their lifetime (fires, illnesses, deforestation, pests…). As an example, the entirety of safety buffers for most forestry projects in California was burnt in the 2023 summer wildfires alone. Consequently, all future losses during the remaining lifetime of the surviving trees will correspond to credits sold that do not equate with carbon removed from the atmosphere. This can not happen with retrospective measurement and Augur’s methodologies.
But carbon is not the be-all and end-all of the challenges our societies face. Several other issues need to be addressed - and hempcrete also contributes to tackling a significant number of them. These environmental, health, economic and social objectives have been compiled by the United Nations under the name of Sustainable Development Goals for 2030 - the blueprint to achieve a better and more sustainable future for all. When attached to a carbon credit project, those other non-carbon-related positive outcomes are called co-benefits.
Hempcrete production contributes to tackling a number of the issues highlighted by the UN and the independent research work on the crucial sustainability role of the Cannabis sativa L. plant towards reaching the 2030 UN SDGs(4). Here are the main ones:
SDG 6: Ensure access for all to sustainably managed water supply and sanitation services
Humanity is consuming too much water. A recent report by UN-Water and UNESCO highlighted the "imminent risk of a global water crisis". This warning echoes the report by the UN's climate experts (IPCC) published last March (2023), according to which "around half of the world's population is experiencing 'severe water scarcity for at least part of the year'".
In a world where, over the last 40 years, the use of freshwater has increased by almost 1% per year, any means of reducing consumption is welcome. According to the French government figures, agriculture is the biggest consumer of water, accounting for 45% of water consumption in the country.
Industry, and construction in particular, is not to be outdone, with 3.3 billion m3 of water, or 10% of water withdrawals but 25% of water consumed (water that is not discharged into the environment). For example, turning cement into concrete requires one-tenth of the water used in industry worldwide. This often puts a strain on drinking water supplies, as 75% of this consumption takes place in regions suffering from drought and water stress.
Hempcrete provides a solution to both these problems, as the crop has low water requirements. Because of the configuration of its root system (deep and taproot), hemp is a relatively drought-resistant crop. In the vast majority of cases, soil supplies are sufficient and irrigation is not economically justified(5). It also retains more water in the soil in which it is grown, which can also affect other crops in rotation. According to the UNCTAD report(6) "Commodities at a Glance: Special Edition on Industrial Hemp", for example, growing hemp leads to a 10-20% increase in wheat yield.
What's more, the production of hempcrete itself has very low water requirements (net freshwater use: 3.49E-01 m3/UF) and no maintenance operations or water use is required during its working life.
SDG 7: Ensure access for all to reliable, sustainable and modern energy services at affordable cost
Saving energy is one, if not, the main lever to ensure we all have enough affordable energy for our basic needs.
The production of traditional building materials is energy intensive(7) - around 700 kW/m3 for solid bricks, 450 kW/m3 for honeycomb bricks and 450 kW/m3 for concrete. Their price is consequently directly dependent on energy prices. Hempcrete, on the other hand, requires no cooking or processing energy once the shiv has been isolated from the rest of the plant. Once scaled up, hempcrete should therefore become a low-cost solution, as well as being less polluting than the alternatives in the construction and insulation market.
What's more, once deployed, hempcrete can also improve energy performance, thanks to its low thermal conductivity (0.065 W/mK) and its ability to store heat in the wall. To this must be added the exchange of water vapour contained in the air with the hempcrete, which enables the daily variations in temperature and hygrometry in a building to be absorbed passively.
As part of the study carried out by Cerema Ile de France on behalf of Construire en Chanvre, with the financial support of the French Ministry of Ecological Transition, simulations have shown that the coupled transfer of heat and humidity within hempcrete walls can reduce the building's heating requirements by 20 kWh/m2/year(8). In other words, the 30 cm of hempcrete behaves "energetically" like 22 cm of hemp wool. This can represent heating savings of up to 70% in the case of a high-performance building.
SDG 8: Promote sustained, shared, and sustainable economic growth, full and productive employment and decent work for all
When we think of industry, we often think of activities that consume a lot of energy and emit CO2. However, the reindustrialisation of a country like France, which has one of the lowest-carbon electricity supplies in the world, is a powerful lever for reducing our carbon footprint. And to this must be added the transport emissions from raw materials and finished products avoided by local production. In 2016, France's carbon footprint stood at around 660 million tonnes of CO2eq, while total emissions linked to domestic production amounted to 440 million tonnes. According to RTE's "Energy Futures 2050" report(9), a third of the emissions linked to French consumption are therefore linked to production abroad.
INSEE estimates show that three-quarters of the final energy consumed by households comes from the grey energy needed to produce the goods imported and consumed(10). Re-industrialising France would therefore play a beneficial role in reducing its carbon footprint. Not to mention the increased 'resilience' of local production, which helps to limit the impact of rising prices and disruptions in the supply chain on the economy.
The decline of our industrial sector has meant that France has lost a huge number of jobs: there are currently only 2.7 million jobs in the industry. The national objective is to boost the industrial sector to 20% of GDP, which would increase the workforce to 4.5 million jobs, or 1.8 million more than at present.
In this way, the "made in France" industry would also create skilled local jobs. These jobs have a virtuous cascade effect: economists estimate that one job created in the industry leads to the creation of 3 jobs in the service sector: transport, design offices, maintenance, security, shops, etc.
Because of transport costs and the relatively low density of shiv, it is not worth importing it. As a result, the activity related to this raw material is constrained to a local location and creates jobs that cannot be relocated to France.
More broadly, recognition of the positive environmental impact of hempcrete through carbon credits should help to strengthen this activity and increase the number of people contributing to it, while maintaining and strengthening areas of excellence in terms of hemp cultivation, primary and secondary processing.
Similarly, because of its virtually zero energy requirements and water independence, hempcrete would, if more widely used, enable so-called "developing countries" to build sustainable production chains that contribute to growth in rural areas and strengthen economic diversification. "Hemp cultivation can help maximise land use and also contribute to increasing the incomes of farmers and rural communities," notes the UNCTAD report on hemp(11). Supporting its development will lower production costs and make it more accessible to these markets.
SDG 9: Build a resilient infrastructure, promote sustainable industrialisation that benefits everyone and encourage innovation
Hempcrete has numerous ecological advantages over other mineral building materials, which largely dominate the market. For example, the manufacture of one tonne of clinker, used in cement, requires the extraction of 1.6 tonnes of limestone - non-renewable materials.
Similarly, sand is a resource that only exists in limited quantities on the planet. Yet it is used in around 200 everyday applications, from water filtration to the manufacture of microprocessors and high-tech products, not to forget glass and concrete (which represent 3/4 of the sand extracted according to the United Nations Environment Programme(12)). This advantage is not insignificant when you consider that up to 40 billion tonnes of sand are extracted every year, according to ADEME(13) (French Environment and Energy Management Agency). This figure could rise to 50 gigatonnes a year by 2030(14). Sand is the second most widely used material in the world after water. It takes 200 tonnes of sand to build a single house, and 30,000 tonnes of sand to build one kilometre of road. As a result of population growth, changing consumption patterns and increasing urbanisation, demand for sand has tripled over the last two decades.
Hempcrete, on the other hand, is made from 3 elements:
hemp fibre (around 80%);
a binder (usually lime);
and water.
The hemp plant grows from the Earth, so it reduces the need for the scarce and polluting mineral resources involved in the manufacture of conventional building materials.
The hemp plant grows in the open air and is generally adaptable to most climates, soil types and altitudes. It has no natural predators or diseases of its own, which ensures a reliable supply. It does not require imported raw materials and energy - which strengthens the national strategic independence and therefore the sustainability of the French construction sector (a large majority of the energy used by industry in France is still of fossil imported origin).
SDG 11: Ensure that cities and human settlements are inclusive, safe, resilient and sustainable
The main raw material for hempcrete is shiv, a renewable resource whose cultivation also regenerates the soil. It therefore allows us to move away from extractive models based on limited resources and high energy and water consumption (see SDGs 6, 7 and 9). In doing so, it enables us to reduce the impact of our cities.
What's more, its improved thermal performance means that buildings' heating energy requirements can be significantly reduced (by between 30 and 70%), which means that hemp buildings will be less energy-intensive. This is no mean feat: in France, over 60% of household energy bills are for heating. So this is the main area of expenditure that needs to be reduced.
These effects could also benefit so-called "developing countries": its global market could reach 18.6 billion dollars in 2027 - almost four times the amount reached in 2020, according to UNCTAD(15). "Easily cultivated and with vast environmental and economic potential, industrial hemp cultivation presents itself as a means of fuelling the growth of sustainable value chains in local and regional markets for many developing countries," adds the report.
Research has shown that hempcrete, once it has reached its end-life, can be fully recycled, crushed or used in construction to replace aggregates, the production of which (in particular, the extraction sites) is a source of substantial environmental impact. Aggregates from loose rock (alluvial deposits, marine aggregates, other sands), solid rock (limestone or eruptive rock), or recycling (demolition materials; slag, shale and aggregates from bottom ash from the incineration of non-hazardous waste) account for 36%, 55% and 9% of emissions respectively. Aggregates from solid rock are derived almost equally from limestone and eruptive rock.
What's more, hempcrete is fully compostable, which means that the biogenic carbon captured by the plant can be transferred to the soil for an unlimited period, provided the soil is not exposed to unsustainable farming techniques.
More broadly, the use of hemp in construction products makes it possible to move away from an extractive model based on limited mineral resources towards a circular model based on cultivation cycles and reinforcing the storage of carbon in overabundance in our atmosphere. In this way, and thanks to its virtues for the soil as described above, it is seen as a substantial player in the transition of the construction sector and in strengthening the sustainability of our consumption patterns.
SDG 13: Take urgent action to combat climate change and its impacts
The biogenic capture and avoided emissions made possible by using hempcrete instead of mineral materials led to a significant reduction in greenhouse gas emissions, resulting in the production of carbon credits. This process is detailed in the PDDs of the projects that Augur Associates supports and has supported.
SDG 15: Conserve and restore terrestrial ecosystems, ensuring their sustainable use, sustainably manage forests, combat desertification, halt and reverse land degradation and halt biodiversity loss.
Human activities tend to have an impact on neighbouring ecosystems. This happens mainly through soil artificialisation, which drives out living things whose habitat is replaced. The use of hempcrete helps to reduce soil artificialisation (quarries, factories, waste treatment sites), which is now one of the main causes of climate change and the erosion of biodiversity. According to the French Ministry for Ecological Transition(16), the spread of our urbanisation and infrastructures extends to between 20,000 and 30,000 hectares every year. This reduction is detrimental to biodiversity, the climate and terrestrial life in general:
Accelerated loss of biodiversity: transforming a natural area into sealed land considerably alters or eliminates the habitat of animal or plant species in this natural area, and can lead to their disappearance from a territory.
Global warming: artificial soil no longer absorbs CO2. Artificial soil therefore contributes to global warming.
Increased risk of flooding: By definition, sealed ground does not absorb rainwater. In the event of severe weather, run-off and flooding are therefore amplified.
Reduced capacity of agricultural land to feed us: artificial development leads to a loss of agricultural productivity and limits food production in our regions.
Increased expenditure on networks: to make it accessible and functional, artificialized land also requires a great deal of maintenance and development work (roads, electricity, drainage), which is costly and often adds to other nuisances to biodiversity (noise pollution, light pollution, air and water pollution)...
Widening the territorial divide: Urban sprawl and building on the outskirts of towns also reinforce the social divide that already exists, in particular by relegating some of the population to the outskirts of town centres, leading to their desertification and the decline in the value of small shops.
In addition, hemp plantations are reservoirs of biodiversity, as highlighted by the life cycle analysis carried out by INRA on hemp(16): the buffer effect of the canopy and the leaf litter on the ground are major assets, providing shelter, moisture and food for all living organisms living in the same area.
Bloc de béton de chanvre BIOSYS® BCE d'épaisseur 30 cm (v.1.1) - INIES
L’empreinte carbone du béton - Infociments (2022)
Sustainable Cannabis Policy Toolkit (Cannabis & Sustainable Development) - FAAAT (2021)
Les atouts du chanvre – Terres Inovia (2019)
Commodities at a glance: Special issue on industrial hemp – CNUCED (2022)
Performance énergétique des bâtiments : une étude montre que le béton de chanvre consomme très peu d’énergie – CEREMA (2021)
Futurs énergétiques 2050 - RTE (2021)
L’emprise énergétique, une façon nouvelle de regarder la consommation d’énergie – INSEE
Commodities at a glance: Special issue on industrial hemp – CNUCED (2022)
Rising demand for sand calls for resource governance – PNUD (2019)
Le sable, une ressource qui pourrait bien nous filer entre les doigts – ADEME (2016)
Sand, rarer than one thinks – UNIGE (2014)
Commodities at a glance: Special issue on industrial hemp – CNUCED (2022)
Artificialisation des sols - Ministère de la transition écologique (2022)
16. Life Cycle Analysis of field production of fibre hemp, the effect of production practices on environmental impacts, INRAE, 2006
Find more technical sources within the special issue on industrial hemp published by the United Nations Conference on Trade and Development (UNCTAD), N°16, 2023.
Find more areas where the hemp plant can contribute to achieving the 2030 UN SDGs within the Cannabis Sustainable Development Toolbook (Published by FAAAT and directed by independent researcher Kenzi Riboulet-Zemouli). 2021