References

297

pathways producing acids and alcohol redirected flux solely toward H2 production,

thereby resulting in a 1.5-fold increase in hydrogen yield.

18.6

Future Perspectives and Conclusion

Biohydrogen has the enormous potential to develop into a sustainable green and

clean energy globally. The major advantage of biohydrogen over other biofuels that

projects it as a clean future fuel is that it produces only water as a side-product dur-

ing energy conversion via combustion or fuel cells. In the last 10 years, numerous

researchers and economists have widely explored various aspects of biohydrogen as

fuel [64]. Literature reports various articles which emphasized on various factors

and technologies to increase the yield of biohydrogen. The conversion of various

wastes to energy by H2 producing microbes is another approach to make the biolog-

ical H2 production economical [64]. Optimization of process parameters, medium

components, substrate concentration, inoculums enrichment, pathway engineering,

bioreactor design, and bioprocess optimization is some of the essential attributes that

are being considered to maximize biohydrogen production. Apart from these strate-

gies, there are other critical traits in the process that must be equally studied. Due to

environmental stress, microbes mutate at a higher rate, and therefore screening of

noble strains for biohydrogen production is very much essential. Development of the

genetic toolkit for these non-model microbes is another challenge that needs to be

overcome fast with developing modern genome editing tools such as CRISPR Cas9,

TALEN, zinc finger nuclease [64]. Moreover, to get insights into the mutations and

the key genes to be targeted for increasing the biohydrogen yield, the construction

of a genome-scale metabolic model and MFA is necessary [55]. A balanced combi-

nation of all these approaches is required to develop a sustainable, economic, and

competitive process for biohydrogen production on a large scale, which can meet

the current demands of the world energy requirements.

This book chapter has described and assessed every aspect involved during the

biological production of H2. Initially, it has elaborated on the routes or pathways

adapted by various microbes for biohydrogen production, and it could be concluded

that dark fermentation is the more efficient route of biological production report-

ing higher yields. It then emphasizes various substrates, including natural organic

matter and waste that provides an attractive solution for fermentative H2 produc-

tion. The development of efficient bioprocess technology, whether batch, contin-

uous, fed-batch, or two-stage process, is the essential feature to be considered for

efficient and large scale production of H2 via biological route. Various strategies

to maximize biohydrogen production have also been assessed critically, providing

insights into future research on biohydrogen.

References

1 Asumadu-Sarkodie, S. and Owusu, P.A. (2016). A review of Ghana’s energy

sector national energy statistics and policy framework. Journal of Cogent Engi-

neering 3: 115–274.