June 10, 2021

After 4 years of intense product development and scale-up activities the CareSTOR Project came to an end by December 2020. Envirohemp brought to a high level of maturity the production of innovative energy-storage grade carbons known as Activated Hydrochar or AHC, a potential replacement of conventional Activated Carbon (AC). This innovative material was produced at the scale of kilograms per day and validated by a world-class Supercapacitor manufacturer, company SECH SA, that took part in the consortium.

As coordinator of the CareSTOR project we have pioneered the production of the first AHC material compliant with the SPECs of the energy storage sector based. One singular feature of AHC is that it can be produced with local biomass residues. This is a major breakthrough in the context of the AC market where all the material used in the EU is currently imported from suppliers located overseas, particularly from in Asia-Pacific.

Factsheet of CareSTOR’s outcomes

The new manufacturing strategy materialized by our company is based on a technology first developed by researchers from INCAR-CSIC and can work as an advantageous replacement for the state-of-the-art methodology due to a number of singular features including its feedstock agnostic character and higher volume of narrow pores suitable for energy storage. Nowadays, AC production combines carbonisation + physical activation while CareSTOR’s disruptive strategy is based on hydrothermal carbonisation + chemical activation.

By mastering this new technology Envirohemp has gained the capacity to produce different versions of AHC with fine-tuned pore size. While microporous AHC (<2 nm) is the preferred option for mainstream Supercapacitors (nicknamed organic or o-CareCAPs), mesoporous AHC (2-5 nm) enables the development of new families of Supercapacitors (aqueous-based or a-CareCAPs and ionic liquid-based or i-CareCAPs).

Upon scaling-up, Envirohemp has demonstrated a new pathway for EU self-sufficiency, validating virtually all types of local lignocellulosic feedstock. This will help overcome the global dependence of the AC industry on coconut shell as the main feedstock.

The first types of prototypes of supercapacitor cells (35 and 60 mm) based on new electrodes coated with AHC and organic electrolytes have been designed by SECH. Those prototypes were put together with the most advanced fabrication technologies currently available in the industry nowadays, enabling an operating voltage of 3.0 V (vs. 2.7 V of most competitors). Overall, it has been demonstrated that a new generation of energy storage devices (o-CareCAPs) can be developed with improved performance due to its reduced Equivalent Series Resistance (ESR). Due to the higher gravimetric capacitance of the new AHC (45 F/g) a reduction of 37% in the total carbon required per device can be achieved. Modules based on o-CareCAPs have been preliminary selected by SECH for their application in regenerative energy systems for sectors such as oil-well pumps and metro stations.

By using mesoporous AHC, SECH ventured into the assembling of a first-of-a-kind i-CareCAP prototype demonstrating a raise of 43% in total energy stored, due to its larger working voltage (3.6 V). In parallel, APowerCap (Ukraine) has developed a new line of supercapacitor prototypes using a greener technology (a-CareCAPs). Unlike conventional supercapacitors, those are based on water-based electrolytes reaching 1.0 V of operating voltage.

In the final months, Envirohemp has commissioned and operated CareSTOR’s flagship plant at TRL 8 (see pictures), featuring hydrothermal carbonisation reactor, clean pyrolysis furnace and high-throughput washing-filtration. Those unique pre-industrial facilities have allowed to establish realistic CAPEX and OPEX. Advanced simulations beyond the 100 ton/yr scale demonstrate that AHC can hit the market with a price of 30-40 €/kg. Optimisation of the technology within the next few months is expected to bring new savings in the production and an even more competitive pricing for AHC.

Hydrothermal carbonisation reactor by ENV
Furnace for clean pyrolysis by ENV