BIOBASED CHEMICALS
‣ NPT currently operates a Refnova precommercial unit on Teesside , UK . This has a capacity of 5,000 tonnes / year , split equally between sugars and biochar . The pre-commercial unit operates on sustainable softwood products . Previous trials have been performed on hardwoods , wheat straw and bagasse .
Markets & applications
Although levoglucosan is an interesting molecule for chiral synthesis , there is currently no established market for its supply . Therefore , the route to a current commercial market is via hydrolysis to glucose . Once converted , it can be used directly as a binding agent or feedstock for sugar surfactants . Glucose can be further processed into a large variety of valuable products . A key product is ethanol . A change of micro-organism in the fermentation step can switch the product to butanol , lactic acid or many other naturally occurring products . Known technologies can convert the ethanol to ethylene , which can then feed a standard petrochemical process . The focus currently is on the move by the aviation sector to SAFs as part of their pledge to achieve net zero . The ethylene is polymerised over selective catalysts and with a touch hydrogenation produces a mix of kerosene which can be separated by distillation . As well as the SAFs , a second fuel stream of renewable diesel is produced . The second output from the Refnova process also has many uses . The applications for biochar are rapidly developing . There are two clear categories for its use ; firstly , where it is used and remains intact and secondly , where it is used as an energy source through combustion ( Figure 4 ). If combusted , the captured CO 2 is released back to the atmosphere . Although this could be claimed to be carbon-neutral , consideration over the time lag to re-grow the biomass needs to be included in the assessment . For example , if wood is used , then a fast-growing tree such as
Figure 4 - Applications of biochar
spruce will take 30 years to capture the CO 2 and replace the biomass used . If a quick-growing crop is used , such as sugar cane , the biomass and therefore the carbon can be replaced within a season . When the biochar is used and the carbon remains intact , such as when it is used as a soil enhancer , the carbon can remain trapped for hundreds or thousands of years . The equivalent CO 2 capture is dependent on the amount of recalcitrant carbon present . For each tonne of permanent carbon storage , 3.6 tonnes of CO 2 would have been removed from the atmosphere . In some of these applications , such as soil enhancement , further CO 2 savings are made . Its porosity means that it retains water . This retention means that valuable nutrients are not washed away out of the soil and hence less additional fertilisers are required . Another saving would occur if the feedstock biomass is normally allowed to rot , releasing both CO 2 and the more potent greenhouse gas , methane .
Net negative
Considering a Refnova unit with capacity of 20,000 tonnes / year using sawmill residues from an existing sustainably managed forest , when turning the sugars into ethanol and
sequestrating the biochar product , there is a 189 % greenhouse gas saving compared to a fossil fuel comparator . This means the process is carbon negative , removing 83 g CO 2 equivalent / MJ of ethanol produced . The annual production would remove 12,000 tonnes / year of CO 2 equivalent to 2,600 cars , as well as producing over 6 million litres of ethanol . The sustainability of a process needs to include more than just the greenhouse gas emissions to Scope 3 . Consideration of any changes to land use and the effects on biodiversity need to be included . As previously mentioned , this includes the time lag of CO 2 emissions and its absorption as new biomass must also be considered . This is particularly important if new forests are established to feed processing units .
* - REFNOVA is a trade mark of Nova Pangaea Technologies
Dr Neil Hindle
CHIEF TECHNICAL OFFICER
NOVA PANGAEA k + 44 1642 440926 J n . hindle @ novapangaea . com j www . novapangaea . com
54 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981