Green Chemistry Centre of Excellence, Department of Chemistry, The University of York, Heslington, York, UK.
ChemSusChem. 2010 Mar 22;3(3):306-22. doi: 10.1002/cssc.200900169.
As a carbon-based life form living in a predominantly carbon-based environment, it is not surprising that we have created a carbon-based consumer society. Our principle sources of energy are carbon-based (coal, oil, and gas) and many of our consumer goods are derived from organic (i.e., carbon-based) chemicals (including plastics, fabrics and materials, personal care and cleaning products, dyes, and coatings). Even our large-volume inorganic-chemicals-based industries, including fertilizers and construction materials, rely on the consumption of carbon, notably in the form of large amounts of energy. The environmental problems which we now face and of which we are becoming increasingly aware result from a human-induced disturbance in the natural carbon cycle of the Earth caused by transferring large quantities of terrestrial carbon (coal, oil, and gas) to the atmosphere, mostly in the form of carbon dioxide. Carbon is by no means the only element whose natural cycle we have disturbed: we are transferring significant quantities of elements including phosphorus, sulfur, copper, and platinum from natural sinks or ores built up over millions of years to unnatural fates in the form of what we refer to as waste or pollution. However, our complete dependence on the carbon cycle means that its disturbance deserves special attention, as is now manifest in indicators such as climate change and escalating public concern over global warming. As with all disturbances in materials balances, we can seek to alleviate the problem by (1) dematerialization: a reduction in consumption; (2) rematerialization: a change in what we consume; or (3) transmaterialization: changing our attitude towards resources and waste. The "low-carbon" mantra that is popularly cited by organizations ranging from nongovernmental organizations to multinational companies and from local authorities to national governments is based on a combination of (1) and (2) (reducing carbon consumption though greater efficiency and lower per capita consumption, and replacing fossil energy sources with sources such as wind, wave, and solar, respectively). "Low carbon" is of inherently less value to the chemical and plastics industries at least in terms of raw materials although a version of (2), the use of biomass, does apply, especially if we use carbon sources that are renewable on a human timescale. There is however, another renewable, natural source of carbon that is widely available and for which greater utilization would help restore material balance and the natural cycle for carbon in terms of resource and waste. CO(2), perhaps the most widely discussed and feared chemical in modern society, is as fundamental to our survival as water, and like water we need to better understand the human as well as natural production and consumption of CO(2) so that we can attempt to get these into a sustainable balance. Current utilization of this valuable resource by the chemical industry is only 90 megatonne per year, compared to the 26.3 gigatonne CO(2) generated annually by combustion of fossil fuels for energy generation, as such significant opportunities exist for increased utilization of CO(2) generated from industrial processes. It is also essential that renewable energy is used if CO(2) is to be utilized as a C1 building block.
作为一种生活在以碳为主要成分的环境中的碳基生命形式,我们创造了一个以碳为基础的消费社会,这并不奇怪。我们的主要能源来源是碳基的(煤、石油和天然气),我们的许多消费品都是从有机(即碳基)化学品中衍生出来的(包括塑料、织物和材料、个人护理和清洁产品、染料和涂料)。即使是我们基于大量无机化学品的大型产业,包括化肥和建筑材料,也依赖于碳的消耗,特别是以大量能源的形式。我们现在面临的环境问题,以及我们越来越意识到的问题,是由于人类活动干扰了地球的自然碳循环,将大量陆地碳(煤、石油和天然气)转移到大气中,主要是以二氧化碳的形式。碳绝不是我们扰乱其自然循环的唯一元素:我们正在将大量包括磷、硫、铜和铂在内的元素从自然汇或经过数百万年积累而成的矿石中转移到我们所谓的废物或污染的非自然命运中。然而,我们对碳循环的完全依赖意味着它的干扰值得特别关注,这在气候变化等指标中表现得很明显,以及公众对全球变暖的日益关注。与所有物质平衡的干扰一样,我们可以通过以下三种方式来减轻问题:(1)去物质化:减少消费;(2)再物质化:改变我们的消费方式;(3)转物质化:改变我们对资源和废物的态度。从非政府组织到跨国公司,从地方当局到各国政府,各种组织都在引用“低碳”口号,这是基于(1)和(2)的结合(通过提高效率和降低人均消费来减少碳消耗,以及分别用风能、波浪能和太阳能替代化石能源)。“低碳”对化学和塑料行业的价值至少在原材料方面较低,尽管(2)的一种版本,即生物质的使用,确实适用,特别是如果我们使用人类时间尺度上可再生的碳源。然而,还有另一种可再生的天然碳源,它广泛可用,更多地利用它将有助于恢复碳的物质平衡和自然循环,无论是资源还是废物。二氧化碳(CO2)可能是现代社会中讨论最多和最令人恐惧的化学物质之一,它与水一样对我们的生存至关重要,我们需要更好地了解人类生产和消耗 CO2 的情况,以便我们能够尝试使其达到可持续的平衡。如果要将 CO2 用作 C1 构建块,那么目前化学工业对这种宝贵资源的利用率仅为每年 9000 万吨,而每年用于能源生产的化石燃料燃烧产生的 CO2 为 263 亿吨。因此,增加工业过程中产生的 CO2 的利用率存在着巨大的机会。如果要利用 CO2,就必须使用可再生能源。