Science AMA Series: I’m Dr Neil Stacey, a biofuels researcher at the
University of the Witwatersrand. I’ve shown that the cost of distilling
ethanol for fuel use can be reduced by just blending gasoline directly
into the ethanol/water mixture. AMA!
Purifying ethanol is energy-intensive and expensive. When we’re just
using it in a fuel blend, it’s also unnecessary. The real end-product of
ethanol production for fuel use isn’t pure ethanol itself but rather a
fuel blend which contains ethanol; pure ethanol need not be an
intermediate step. Reconsidering the overall flow-sheet in this way
opens up a far broader optimization space in which to find
energy-efficient separation processes and in a recent Energy and Fuels
paper, my colleagues and I demonstrated a more energy-efficient
separation process making use of a natural liquid phase split to
eliminate water without the addition of further energy for separation.
Our process cuts the energy consumption of ethanol production by up to
2MJ per liter and has a lower capital cost than conventional azeotropic
distillation. It is, however, just one of many new processes that become
possible once you discard the assumption that a pure biofuel is the
ultimate end-product. I am here with Shell engineer Ari Hadjitheodorou
to talk about the challenges of implementing this concept in the field.
Ask us anything! Questions about the violent #FeesMustFall protests on
our campus are not off-limits, though we prefer to stick to the science.
We will be back at 11 am ET (8 am PT) to answer your questions, ask us
anything! Edit: Link to paper. Sadly our currency in South Africa has
recently stopped being worth anything, so the university wouldn’t fork
out the fee for Open Access, so here’s a link to a news article that
summarizes it. Edit2: It’s 7PM over here, so I need to do some
real-world stuff (dinner, human contact etc) so I’ll be wrapping up for
now. I’ll stop by again in the morning to answer anything else that’s
come up. Thanks everyone for the questions and the support and a big
thank you to the mods!