The po en ial o mic oalgae biomass om u ban was ewa e ea men o bio uel
p oduc ion by py olysis: lash e sus con en ional p ocesses in he EU FLEXBY p ojec
R. Pa do, L. Taboada-Ruiz, E. Ciu cina, J. Holgado, P. Ál a ez Rod íguez, M. Díaz-Somoano, B. Ruiz
Ca bon Science and Technology Ins i u e (INCAR), CSIC. C/ F ancisco Pin ado Fe 26, 33011, O iedo, Spain.
Keywo ds: mic oalgae, was ewa e , py olysis, bio-oil
P esen ing au ho email: od [email p o ec ed]
In oduc ion
Mic oalgae ha e eme ged as a highly p omising solu ion in he ques o sus ainable ene gy sou ces, due o hei
apid g ow h a es, high pho osyn he ic e iciency, and capaci y o u ilize was ewa e as a nu ien - ich cul i a ion
medium. By h i ing in municipal was ewa e , mic oalgae o e a dual bene i : hey con ibu e o was ewa e
ea men while simul aneously p oducing biomass ha can be con e ed in o bio-oil and biocha , which se e as
a enewable bio uel sou ce and a e ilize , espec i ely. Thei abili y o cap u e signi ican amoun s o CO2 du ing
g ow h u he enhances hei en i onmen al impac by helping o mi iga e ca bon emissions (Hai e al., 2024).
Py olysis, pa icula ly lash py olysis, is a key p ocess in he con e sion o mic oalgal biomass in o
aluable bio-oil. This he mochemical p ocess o e s he apid decomposi ion o biomass and e icien eco e y
o ene gy- ich p oduc s such as bio-oil, bio-cha , and gases. Flash py olysis, wi h i s as e hea ing a es and sho e
esidence imes, o e s ad an ages such as highe bio-oil yields and imp o ed ene gy e iciency compa ed o
con en ional py olysis me hods (Ślęzak e al., 2022). Py olysis me hod could also in luence he composi ion and
cha ac e is ics o he bio-oil, highligh ing he impo ance o selec ing he app op ia e py olysis me hod depending
on he desi ed uel p ope ies
This in eg a ed sys em no only add esses he need o cleane ene gy bu also educes he en i onmen al
bu den o was ewa e managemen , p esen ing a ci cula app oach ha links esou ce eco e y wi h enewable
ene gy p oduc ion. Consequen ly, mic oalgae-based bio uels, p oduced h ough ad anced py olysis echniques,
hold signi ican po en ial o con ibu e o he ansi ion owa ds a low-ca bon, sus ainable ene gy u u e.
Me hodology
Mic oalgae we e cul i a ed in municipal was ewa e a e seconda y ea men . Following ha es ing, he
mic oalgal biomass was d ied and p epa ed o py olysis.
Two py olysis me hods we e employed: con en ional py olysis (CP) and lash py olysis (FP). Fo he
con en ional py olysis, a specially designed cylind ical elec ic u nace, ope a ing ho izon ally, was used. The
d ied mic oalgae biomass was loaded in o he u nace a ambien empe a u e, and ni ogen gas was lowed a a
a e o 100 ml/min o c ea e an ine a mosphe e. The hea ing p o ocol in ol ed a amp a e o 25°C pe minu e,
eaching a inal py olysis empe a u e o 500°C. Once he empe a u e was achie ed, he sample was main ained
a 500°C o one hou o ensu e comple e con e sion. In he case o lash py olysis, he u nace was p ehea ed o
he ope a ing empe a u e o 500°C. The mic oalgae biomass was hen ed in o he u nace once his empe a u e
was eached. Following py olysis, h ee di e en ac ions we e collec ed om bo h p ocesses: bio-cha , bio-oil,
and gases. These ac ions we e subsequen ly quan i ied and analyzed.
Resul s
Flash py olysis esul ed in a no able shi in p oduc dis ibu ion, a o ing he liquid ac ion (bio-oil) o e
he gaseous ac ion (Fig. 1). Con en ional py olysis p oduced a bio-oil yield o 27% and a gas yield o 24%. In
con as , lash py olysis inc eased he bio-oil yield o 34% while educing he gas yield o 18%. This shi can be
a ibu ed o he apid hea ing a es and sho e esidence imes in lash py olysis, which minimize seconda y
c acking eac ions and allow mo e ola iles o condense in o liquid bio-oil a he han o ming gas (Ma ques e al.,
2024). Bo h con en ional and lash py olysis yielded compa able amoun s o biocha , wi h biocha yields
emaining consis en ly a 49%, clea ly d i en by he ash con en , which o his biomass usually a ies be ween
20-30%.
Fig. 1. Py olysis ac ions yields (%)
Addi ionally, he biocha ob ained could be o g ea in e es due o i s high mine al con en (Table 1),
including calcium (3.4%), phospho us (1.34%), and magnesium (4.76%), making i sui able as a soil amendmen
o e ilize . These mine als a e essen ial o plan nu i ion and can enhance soil e ili y. The e o e, his ma e ial
can p o ide he common bene i s o biocha in soil, such as imp o ing soil ex u e, wa e e en ion, inc easing
mic obial ac i i y, pollu an adso p ion, and ca bon ixa ion. Addi ionally, i can supply essen ial nu ien s o
plan s, making his ma e ial pa icula ly aluable (Ma ousek e al., 2024).
Table 1. Ino ganic composi ion o mic oalgae cul i a ed in was ewa e (%)
Mg
Ca
Si
P
Na
K
Al
Fe
Cl
S
4.8
3.4
1.4
1.3
0.7
0.4
0.2
0.1
0.1
0.1
P elimina y da a also sugges s ha he composi ion and p ope ies o he bio-oil ob ained om lash
py olysis di e s om ha p oduced h ough con en ional py olysis. Fu he analysis is equi ed o ully
cha ac e ize hese di e ences. These dis inc cha ac e is ics could in luence he po en ial applica ions o he bio-
oil, making lash py olysis a p omising echnique o op imizing he quali y and yield o bio uels om mic oalgal
biomass.
Conclusions
The esul s o he py olysis expe imen s indica e ha mic oalgae biomass cul i a ed in was ewa e is a
highly sui able eeds ock o sus ainable bio uels de i ed om bio-oil p oduc ion. In pa icula , lash py olysis
demons a ed a signi ican ad an age by inc easing he yield o bio-oil by 25%, making i a mo e e icien p ocess
o liquid uel p oduc ion. The consis en biocha yields (a ound 49%) in bo h py olysis me hods highligh i s
po en ial as a sou ce o solid ca bon- ich ma e ials, which ha e aluable applica ions in bo h ag icul u e and
emedia ion. The high mine al con en o he biocha makes i a aluable e ilise , p o iding he common bene i s
o biocha in soil, as well as se ing as a sou ce o nu ien s. This con ibu es o ci cula economy p inciples by
in eg a ing bio uel p oduc ion wi h soil imp o emen and was ewa e ea men .
Acknowledgmen s
The wo k desc ibed in his publica ion was subsidised by Ho izon Eu ope (HORIZON) amewo k
h ough he G an Ag eemen Numbe 101144144. Addi ionally, he au ho s hank A4F (Algae o Fu u e) o
p o iding he mic oalgae biomass used in his wo k
Re e ences
Hai , S., Gawali, S., Awa ha e, P., Nawaj Alam, S., Singh, B., Guldhe, A., 2024. In eg a ed app oach o mic oalgal
biomass gene a ion using poul y li e and was ewa e -based media and i s applica ion o bio-oil
p oduc ion. Ene gy Con e s. Manag. 313, 118610. h ps://doi.o g/10.1016/j.enconman.2024.118610
Ma ousek, J., Ga u o a, B., Ma ousko a, A., 2024. Cos b eakdown indica es ha biocha p oduc ion om
mic oalgae in Cen al Eu ope equi es inno a i e cul i a ion p ocedu es. Ene gy Nexus 16, 100335.
h ps://doi.o g/10.1016/j.nexus.2024.100335
Ma ques, J. de A.O., Al es, J.L.F., de Oli ei a, G.P., Melo, D.M. de A., de Melo Viana, G.A.C., B aga, R.M.,
2024. Ca aly ic lash py olysis o Scenedesmus sp. pos -ex ac ion esidue using low-cos HZSM-5
ca alys wi h he pe spec i e o p oduce enewable a oma ic hyd oca bons. En i on. Sci. Pollu . Res. 31,
18785–18796. h ps://doi.o g/10.1007/s11356-024-32336-8
Ślęzak, R., Naw o , P., Ledakowicz, S., 2022. Py olysis o mic o- and mac oalgae in he mobalance coupled wi h
mass spec ome e . Algal Res. 66, 102782. h ps://doi.o g/10.1016/j.algal.2022.102782
Funded by he Eu opean Union. Views and opinions exp essed a e howe e hose o he
au ho (s) only and do no necessa ily e lec hose o he Eu opean Union o CINEA.
Nei he he Eu opean Union no he g an ing au ho i y can be held esponsible o hem.
010 20 30 40 50 60
Gas yield
Bio-Oil yield
Biocha yield
Flash
Con en ional
