Beyond Solar Fuels: Renewable Energy‐Driven Chemistry

Abstract

The ongoing energy transition based on the substitution of fossil feedstocksa se nergy sourcesw ith renewablee nergy (RE) sourcesdemands reconsideration of current industrial chemical production,w hich is anticipated to be at the end of this cycle. The main element determining greenhouse gas (GHG) emissions during chemical production is the use of fossil fuels to drive chemical transformations, rather than their use as sources of carbon.F urthermore, RE will become progressively cheaper as as ource of energy with respectt ot hat derived fromf ossil fuels and new chemical raw materials such as methanol, derived from the conversion of waste CO 2 ,w illb ecome available on al arge scale, being used as energy vectors to transport RE on ag lobals cale. There are thus converging sustainability elements indicating the need to move to af uture scenario of chemicali ndustrialp roduction denoted as "RE-driven chemistry", which can also provide ag reat opportunity for innovation and competitivity in chemical industry.I nt his Essay we discuss how it is realistic to conceive of RE-driven chemistry,w hich will be an on-incremental change to move to al ow-carbon economy,t hat is, with ad ecreasei nG HG emissions by up to 80 %. However,t his objective requires the fulfillment of two criteria: i) the use of RE-driven processes for the production of base raw materials, such as olefins,m ethanol, and ammonia,w hich are at the top of the chemical production value chain and ii)the development of RE-driven routes that simultaneously realize process and energy intensification, that is, which combine the use of RE in substitution of fossil fuels to significantly reducethe number of the process steps. Twospecific examples of using RE to realize novel conversion pathways are discussed: the direct synthesies of ammonia from N 2 andH 2 Oa nd that of acetic acid from CO 2 and H 2 O. They exemplify the above concept and the possibility of ar eductiono fo ver 80 % in GHG emissions. Some aspects of the production of olefins from renewable methanola re also discussed. Enabling this vision of an ew chemical industrial production based on the use of RE requires significant investment in new production technologies, because an on-incremental change in chemical industry-thedevelopment of newm aterials, reactors and processes( for example, based on the use of electrons and photons rather than heat as today)-is an ecessity.T hese novel technologiesw ill offer the opportunity to overcome the actual industrial process, by switching from largei ntegrated chemical plantst oad istributed modelo fp roduction with various sustainability benefits.

Recent Progress in Decoupled H2 and O2 Production from Electrolytic Water Splitting

“…However, the diurnal cycle of sunlight renders solar energy intermittent nature . Solar‐driven water splitting has been acknowledged as an appealing strategy in storing solar energy in chemical forms like H 2 , which can be used on demand . Due to the relatively low intensity of solar irradiation, a benchmark current density of solar‐driven water splitting is merely 10 mA/cm 2 .…”

“…[23] Solar-driven water splitting has been acknowledged as an appealing strategy in storing solar energy in chemical forms like H 2 , which can be used on demand. [24][25][26][27] Due to the relatively low intensity of solar irradiation, a benchmark current density of solar-driven water splitting is merely 10 mA/cm 2 . Such a low current density results in slow production of H 2 and O 2 and hence leads to severe gas permeation and H 2 /O 2 crossover.…”

The Past, Present, and Future of Sustainable Chemistry

“…While ten years ago the focus was still on topics related to what was indicated as the 12 Principles of Green Chemistry, today it is becoming clear that this is a somewhat limited vision. The focus of sustainable chemistry is now on forming the (low‐carbon) chemistry of the future, with the development of novel technologies that can revolutionize chemical production in terms of process and energy intensification by using renewable energy‐ or solar‐driven chemistry . An example is the development of new processes for the production of base chemicals by direct use of renewable energy rather than fossil fuels.…”

“…The focus of sustainable chemistry is now on forming the (low-carbon)c hemistry of the future,w ith the development of novel technologiest hat can revolutionize chemical production in terms of process and energy intensificationb y using renewable energy-or solar-driven chemistry. [3] An example is the development of new processes for the productiono f base chemicals by directu se of renewable energy rather than fossil fuels. Direct ammonia synthesis from nitrogen and water can not only reduce by over 90 %t he carbon footprint, but also opens up an ew innovationl andscape that goes beyond chemicalp roduction.…”

Needs and Gaps for Catalysis in Addressing Transitions in Chemistry and Energy from a Sustainability Perspective

“…[3] Electrocatalysis is not a mere extension of traditional electrochemistry,b ut new methods and materials must be developed to maximize its potential in the future of appliedc hemistry. New approaches are necessary for selective conversion with high reactionr ates.…”