Biofuels future and criticism - 未名空间MITBBS历史存档

Biofuels future and criticism# ChemEng - 化学工程

x*c2011-10-12 07:10

1 楼

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z*h2011-10-12 07:10

2 楼

Highlights
► We are flooded by a wave of biased or even false information about
biofuels.
► Most advanced biofuels cannot be economically produced compared to
ethanol and H2.
► Thermodynamics determines economics.
► Cellulosic ethanol and butanol are the best short- and middle-term
biofuels.
► Sugary hydrogen would be the best ultimate biofuel.
Abstract
doi:10.1016/j.procbio.2011.08.005
Since biofuels is a hot topic, many researchers new to this field are eager to propose different solutions while they often seem not to have full understanding of the current status of technologies and numerous (hidden) constraints. As a result, the general public, policymakers, academic researchers, and industrial developers have been assaulted by a wave of biased, misinterpreted, or outright false information. In reality, only a small fraction of exploding biofuels R&D teams are addressing vital rather than trivial challenges associated with economically production of advanced biofuels. Biofuels R&D is not a completely basic science project; instead, it is a typical goal-oriented (engineering) project because so many constraints prevent economically competitive production of most advanced biofuels and are expected to do so in the future. In this opinion paper, I
present some basic rules and facts in thermodynamics, physical chemistry, and special constraints in the transport sector, sort through and challenge some claimed breakthroughs or new directions, and identify vital topics to advance biofuels in the short and long terms. Simply speaking, energy efficiency is the most important long-term criterion whereas cost is the most important short-term criterion; eventually thermodynamics determines economics. For light-duty passenger vehicles, which consume ∼60% transportation fuels, cellulosic ethanol and butanol are the best short- and middle-term biofuels, whereas sugary hydrogen would be the ultimate biofuel in the long term. The top three priorities of biofuels R&D are (i) cost-effective release of sugars from lignocellulose, (ii) co-utilization of lignocellulose components for the production of value-added compounds that subsidize whole biorefineries, and (iii) enhancing the biomass-to-kinetic energy efficiency from conversions to prime movers through a potential evolutionary scenario from ethanol or butanol/internal combustion engines (ICE) to ethanol/hybrid diesel-like ICE to sugar hydrogen fuel cell vehicles.

S*n2011-10-12 07:10

3 楼

completely agree
不过我觉得短期的话，bio-based chemical比biofuel靠谱一点。。。

eager
advanced

【在 z*h 的大作中提到】

: Highlights
: ► We are flooded by a wave of biased or even false information about
: biofuels.
: ► Most advanced biofuels cannot be economically produced compared to
: ethanol and H2.
: ► Thermodynamics determines economics.
: ► Cellulosic ethanol and butanol are the best short- and middle-term
: biofuels.
: ► Sugary hydrogen would be the best ultimate biofuel.
: Abstract

z*h2011-10-12 07:10

4 楼

Of course chemical compounds are much better than biofuels. Now it is hard
to make money from biofuels now.

S*n2011-10-12 07:10

5 楼

what about KiOR? their performance seems good...although with government
incentives, but still looks good

【在 z*h 的大作中提到】

: Of course chemical compounds are much better than biofuels. Now it is hard
: to make money from biofuels now.

s*e2011-10-12 07:10

6 楼

同问，听说过kior,他家的技术真有那么好吗？

b*n2011-10-12 07:10

7 楼

the technology is FCC, which is traditional process in refining. The key is
catalyst.

【在 s****e 的大作中提到】

: 同问，听说过kior,他家的技术真有那么好吗？

y*a2011-10-12 07:10

8 楼

bio-based chemical利润肯定要高，但用户要求度会更高，同时替代产品也更多。综合
来看，不一定就真的比biofuel赚钱。
另外对原文认为sugary H2是最终解决方案持保留意见。

【在 S*****n 的大作中提到】

: completely agree
: 不过我觉得短期的话，bio-based chemical比biofuel靠谱一点。。。
:
: eager
: advanced

y*a2011-10-12 07:10

9 楼

基本技术应该是pyrolysis，可能在后期upgrading时用的catalysts有优势吧。

【在 S*****n 的大作中提到】

: what about KiOR? their performance seems good...although with government
: incentives, but still looks good

z*h2011-10-12 07:10

10 楼

Pyrolysis has too low product yields although it has low capital investment
and can use broad feedstock.
Sugary H2 production is a net energy gain process (output is 22% more than
input). No technology can achieve it before. Also, hydrogen is cleanest for
end users. It is why it will be a final winner compared to most energy
generation or conversion systems.

z*h2011-10-12 07:10

11 楼

Based on catalysts.
When substrates have so many OH group or O, they can be catalyzed well by
enzymes. When substrate have dominant CH and C, traditional catalysts are
better.
based on efficiency.
Biocatalysts are far better.
Based on rates.
Catalysis are better.
So we need evaluate which we need most. and decide how to go.

y*a2011-10-12 07:10

12 楼

For the net energy gain, if can produce energy from waste materials, the
input energy can be zero or even negative value. From this aspect,the energy
gain can be easily higher than 100%.
H2 is clean but more difficult to be transported and stored than
conventional fuel. Not only the current infrastructure, but most of the
engines need to be redesigned if H2 is used as the primary fuel in the
future.

investment
for

【在 z*h 的大作中提到】

: Pyrolysis has too low product yields although it has low capital investment
: and can use broad feedstock.
: Sugary H2 production is a net energy gain process (output is 22% more than
: input). No technology can achieve it before. Also, hydrogen is cleanest for
: end users. It is why it will be a final winner compared to most energy
: generation or conversion systems.

z*h2011-10-12 07:10

13 楼

Net energy gain is very hard. The use of waste materials (chemical energy)
from the generation of thermal energy or other chemical energy forms is not
net energy gain. Read the conversion of energy matrix in Table.

b*o2011-10-12 07:10

14 楼

transportation fuels from renewable biomass is a joke

y*a2011-10-12 07:10

15 楼

well, name something that is not so funny.

【在 b*****o 的大作中提到】

: transportation fuels from renewable biomass is a joke

b*o2011-10-12 07:10

16 楼

The production of transportation fuels from biomass, relies on the premise
that biomass is a resource available in excess amounts, a premise which will
likely not hold in the future. Not to say high costs, relatively low
production rates, etc.

【在 y********a 的大作中提到】

: well, name something that is not so funny.

y*a2011-10-12 07:10

17 楼

It depends on whether energy crop can be successfully produced in large area
or not. And the definition of biomass could be broader.
Your concern is reasonable, that's why this kind of work is mainly in the
lab orpilot scale now. However, many other researches have the same
situation before they were fully commercialized. The technical breakthoughs
are needed in this area. But is this different with others?

will

【在 b*****o 的大作中提到】

: The production of transportation fuels from biomass, relies on the premise
: that biomass is a resource available in excess amounts, a premise which will
: likely not hold in the future. Not to say high costs, relatively low
: production rates, etc.

z*h2011-10-12 07:10

18 楼

Highlights
► We are flooded by a wave of biased or even false information about
biofuels.
► Most advanced biofuels cannot be economically produced compared to
ethanol and H2.
► Thermodynamics determines economics.
► Cellulosic ethanol and butanol are the best short- and middle-term
biofuels.
► Sugary hydrogen would be the best ultimate biofuel.
Abstract
doi:10.1016/j.procbio.2011.08.005
Since biofuels is a hot topic, many researchers new to this field are eager to propose different solutions while they often seem not to have full understanding of the current status of technologies and numerous (hidden) constraints. As a result, the general public, policymakers, academic researchers, and industrial developers have been assaulted by a wave of biased, misinterpreted, or outright false information. In reality, only a small fraction of exploding biofuels R&D teams are addressing vital rather than trivial challenges associated with economically production of advanced biofuels. Biofuels R&D is not a completely basic science project; instead, it is a typical goal-oriented (engineering) project because so many constraints prevent economically competitive production of most advanced biofuels and are expected to do so in the future. In this opinion paper, I
present some basic rules and facts in thermodynamics, physical chemistry, and special constraints in the transport sector, sort through and challenge some claimed breakthroughs or new directions, and identify vital topics to advance biofuels in the short and long terms. Simply speaking, energy efficiency is the most important long-term criterion whereas cost is the most important short-term criterion; eventually thermodynamics determines economics. For light-duty passenger vehicles, which consume ∼60% transportation fuels, cellulosic ethanol and butanol are the best short- and middle-term biofuels, whereas sugary hydrogen would be the ultimate biofuel in the long term. The top three priorities of biofuels R&D are (i) cost-effective release of sugars from lignocellulose, (ii) co-utilization of lignocellulose components for the production of value-added compounds that subsidize whole biorefineries, and (iii) enhancing the biomass-to-kinetic energy efficiency from conversions to prime movers through a potential evolutionary scenario from ethanol or butanol/internal combustion engines (ICE) to ethanol/hybrid diesel-like ICE to sugar hydrogen fuel cell vehicles.

S*n2011-10-12 07:10

19 楼

completely agree
不过我觉得短期的话，bio-based chemical比biofuel靠谱一点。。。

eager
advanced

【在 z*h 的大作中提到】

: Highlights
: ► We are flooded by a wave of biased or even false information about
: biofuels.
: ► Most advanced biofuels cannot be economically produced compared to
: ethanol and H2.
: ► Thermodynamics determines economics.
: ► Cellulosic ethanol and butanol are the best short- and middle-term
: biofuels.
: ► Sugary hydrogen would be the best ultimate biofuel.
: Abstract

z*h2011-10-12 07:10

20 楼

Of course chemical compounds are much better than biofuels. Now it is hard
to make money from biofuels now.

S*n2011-10-12 07:10

21 楼

what about KiOR? their performance seems good...although with government
incentives, but still looks good

【在 z*h 的大作中提到】

: Of course chemical compounds are much better than biofuels. Now it is hard
: to make money from biofuels now.

s*e2011-10-12 07:10

22 楼

同问，听说过kior,他家的技术真有那么好吗？

b*n2011-10-12 07:10

23 楼

the technology is FCC, which is traditional process in refining. The key is
catalyst.

【在 s****e 的大作中提到】

: 同问，听说过kior,他家的技术真有那么好吗？

y*a2011-10-12 07:10

24 楼

bio-based chemical利润肯定要高，但用户要求度会更高，同时替代产品也更多。综合
来看，不一定就真的比biofuel赚钱。
另外对原文认为sugary H2是最终解决方案持保留意见。

【在 S*****n 的大作中提到】

: completely agree
: 不过我觉得短期的话，bio-based chemical比biofuel靠谱一点。。。
:
: eager
: advanced

y*a2011-10-12 07:10

25 楼

基本技术应该是pyrolysis，可能在后期upgrading时用的catalysts有优势吧。

【在 S*****n 的大作中提到】

: what about KiOR? their performance seems good...although with government
: incentives, but still looks good

z*h2011-10-12 07:10

26 楼

Pyrolysis has too low product yields although it has low capital investment
and can use broad feedstock.
Sugary H2 production is a net energy gain process (output is 22% more than
input). No technology can achieve it before. Also, hydrogen is cleanest for
end users. It is why it will be a final winner compared to most energy
generation or conversion systems.

z*h2011-10-12 07:10

27 楼

Based on catalysts.
When substrates have so many OH group or O, they can be catalyzed well by
enzymes. When substrate have dominant CH and C, traditional catalysts are
better.
based on efficiency.
Biocatalysts are far better.
Based on rates.
Catalysis are better.
So we need evaluate which we need most. and decide how to go.

y*a2011-10-12 07:10

28 楼

For the net energy gain, if can produce energy from waste materials, the
input energy can be zero or even negative value. From this aspect,the energy
gain can be easily higher than 100%.
H2 is clean but more difficult to be transported and stored than
conventional fuel. Not only the current infrastructure, but most of the
engines need to be redesigned if H2 is used as the primary fuel in the
future.

investment
for

【在 z*h 的大作中提到】

: Pyrolysis has too low product yields although it has low capital investment
: and can use broad feedstock.
: Sugary H2 production is a net energy gain process (output is 22% more than
: input). No technology can achieve it before. Also, hydrogen is cleanest for
: end users. It is why it will be a final winner compared to most energy
: generation or conversion systems.

z*h2011-10-12 07:10

29 楼

Net energy gain is very hard. The use of waste materials (chemical energy)
from the generation of thermal energy or other chemical energy forms is not
net energy gain. Read the conversion of energy matrix in Table.

b*o2011-10-12 07:10

30 楼

transportation fuels from renewable biomass is a joke

y*a2011-10-12 07:10

31 楼

well, name something that is not so funny.

【在 b*****o 的大作中提到】

: transportation fuels from renewable biomass is a joke

b*o2011-10-12 07:10

32 楼

The production of transportation fuels from biomass, relies on the premise
that biomass is a resource available in excess amounts, a premise which will
likely not hold in the future. Not to say high costs, relatively low
production rates, etc.

【在 y********a 的大作中提到】

: well, name something that is not so funny.

y*a2011-10-12 07:10

33 楼

It depends on whether energy crop can be successfully produced in large area
or not. And the definition of biomass could be broader.
Your concern is reasonable, that's why this kind of work is mainly in the
lab orpilot scale now. However, many other researches have the same
situation before they were fully commercialized. The technical breakthoughs
are needed in this area. But is this different with others?

will

【在 b*****o 的大作中提到】

: The production of transportation fuels from biomass, relies on the premise
: that biomass is a resource available in excess amounts, a premise which will
: likely not hold in the future. Not to say high costs, relatively low
: production rates, etc.

z*h2011-10-12 07:10

34 楼

Surpassing Photosynthesis: High-Efficiency and Scalable CO2 Utilization
Through Artificial Photosynthesis
Plants like solar cells utilize intermittent non-point insolation to
biologically fix CO2 in the form of biomass carbohydrates. However, plant
photosynthesis has pretty low solar energy-to-chemical energy conversion
efficiencies (e.g., ~0.2-0.3%, global average) and consumes a large amount
of water (i.e., at least 500 kg of water per kg of biomass generated). Such
low energy efficiencies are mainly attributed to three factors: (i) a
narrow light absorption spectrum by chlorophyll, (ii) relatively low
efficiencies of carbohydrate synthesis and unmatched reaction rates between
fast light-harvesting reactions and slow dark chemical synthesis reactions,
and (iii) carbohydrate losses due to the respiration of living plants.
To surpass these limitations in plants, we design a novel scalable
bioprocess integrating high-efficiency solar cells, water electrolysis, and
biological CO2 fixation mediated by cascade enzymes for the similar function
. This synthetic enzymatic pathway containing in vitro numerous enzymes and
coenzymes would fix CO2 into carbohydrates (e.g. starch) and/or ethanol by
using electricity or hydrogen. Such in vitro synthetic enzymatic pathways
are believed to work based on the design principles of synthetic biology,
knowledge in the literature, and thermodynamics analysis. However,
validation experiments and practical application of these systems will
require collaborative efforts from biologists, chemists, electrochemists,
and engineers. Here we present our latest advances in the proof-of-concept
experiment. Large-scale implementation of this artificial photosynthesis
would address such sustainability challenges as electricity and hydrogen
storage, CO2 utilization, fresh water conservation, and maintenance of a
small closed ecosystem for human survival in emergency situations.

z*h2011-10-12 07:10

35 楼

The above abstract is our dream. Hope that solar cells or fusion will have
big breakthroughs. If yes, humans will solve all remaining problems from
energy to food to water to climate change.