By Rupert Blackstone
with contributions from Roger Middleton, Brian Robinson and Ian Arbon
Although many of us, if not most of us, have some idea of what sustainability means conceptually, how many of us have an idea of what this means in terms of our lifestyle and personal responsibilities? Where the progress of society towards a sustainable future may be viewed as inadequate, it may be easy for us to blame governments and corporations, but given that the activities of governments and organisations serve individuals, what can we as individuals do and influence? How can engineers empower and equip us to live sustainably from day to day and what might a sustainable lifestyle look like? This is the first in a series of Energy, Environment and Sustainability Group (EESG) articles on what a sustainable lifestyle might mean in practice and what engineers can do to influence this. This is an extensive and complex subject that cannot be done justice in one article, but hopefully as we develop the theme there may be an exchange of ideas that can help us all move in the right direction.
Sustainability is generally understood to mean something along the lines of not consuming resources faster than their production and not polluting the environment in an irreversible way. These resources may be environmental, economic or indeed societal. Many people believe they are living sustainably because they are doing better than others around them by for example separating their rubbish for recycling more than others or riding a bicycle to work rather than driving. How do we know though if we are doing enough? Even those who work professionally in the area of sustainability rarely have truly sustainable lifestyles themselves, even if they advocate them for others. Often people suggest that they are not prepared to live sustainably as individuals until there is a collective movement with those around them doing the same; otherwise there is a feeling of self-sacrifice with little notable impact whilst those around them continue to live in relative luxury. Furthermore responsibility is often transferred when it is said that we need the development of centralised systems before we can live a fully sustainable lifestyle. For example, it is often asked, 'Why should we avoid using our car if the bus and railway systems are so inadequate?'
Approach towards understanding the practical consideration of sustainability in our lifestyles
For us to understand the potential both for sustainable engineering solutions and sustainable lifestyle choices, we may consider the sustainability of our lifestyles through subdivision into the following categories:
- Energy including transport
- Finite resource depletion and waste management
In fact there is much overlap between these categories, so the subdivision is not rigid. For example water and energy can have opposing sustainability impacts – desalination uses an abundant water resource but uses much energy; and concentrating solar power (CSP) makes use of an abundant energy resource but may draw from limited water resources for cooling. Certain new designs of wind turbines, which generate energy from a sustainable resource, are dependent on a rare earth, neodymium, which apart from being a scarce resource has a significant environmental impact. There are more common elements that are in short supply such as lead (used for lead acid batteries) and copper (used for cabling and other electrical components), presenting significant challenges for the extensive introduction of electric vehicles, which receive widespread support for a sustainable transport future, as alluded to further on in the article.
Using these categories as guidance, we may consider what we as citizens can do to live sustainably in our everyday lives and also consider the role of engineers in developing systems to help us live more sustainably.
How are we living at the moment?
The resources we need to support our current lifestyles, if they are not finite, are generated over differing timescales. The rate of consumption of these resources by humans is related to population. We need therefore to consider our lifestyles in the context of an increasing population. It might be said that the lifestyles that many of us in the UK have at the moment might be reasonably sustainable if there were many fewer of us on Earth and the population were stable. In the UK there is often a sense of futility when people question what differences to the world changes in their own lifestyle will make when there are rapidly growing populations in other countries, for example, China and India. What is not always recognised is that the per capita the impact of these countries is far lower - for example on average in the UK we have an impact that is around three times as much as that which is sustainable for the global population (UNDP Human Development report). However it should be noted that the energy consumption per capita of these countries is rising very rapidly. It should be recognised that much of the impact we associate with countries such as China is as a direct result of activities in the West. When we compare our national greenhouse gas emissions as a nation with those of other countries, the governmentally approved accounting mechanisms generally fail to take into account the emissions associated with our consumption of products that have been produced elsewhere, or of the emissions from shipping the goods around the world. When this is taken into account the picture for the UK looks less satisfactory.
How do we measure the impact?
Before we start considering what improvements we might make to our lifestyle, we need to have a means of measuring them. Not only do we need to know what to do, but we need to know how much to do. The problem is that sustainability refers to many different flows of material and energy so we need to find ways of navigating complexity. One commonly used method is lifecycle assessment. Resource consumption and waste production and their associated impacts are modelled over the lifecycle of a system or product. This has a significant scientific component in the determination of physical impacts, but then becomes somewhat subjective when the relative importance of the impacts is assessed. For example, which is more of a concern – respiratory disease from local pollution or flooding as a result of sea level change? You might get a different answer from someone in London and someone in Dhaka. This illustrates the importance of gauging the social aspect of sustainability. Some people might be happy living in a high technology sprawling urban jungle surrounded by monocultural genetically modified crops, whereas others may prefer a world with humans living more in harmony with nature. Clearly we need somehow to balance the needs of the world’s population, but perhaps the most important requirement is to empower people to make informed decisions. The range of data presented to us and the extent of conflicting information can be overwhelming, and it can be difficult to know what is best. The right answer is not always obvious. For example, what form of hand drying has the least lifecycle environmental impact – disposable paper towels, washable towelling in a rotary dispenser or electric hand drying (answer at the end of the article)? And are those biodegradable plastic shopping bags really a good idea when they require comparable amounts of energy for their manufacture as an ordinary plastic shopping bag, which can at least be partially converted back into useable energy or recycled? With time the truth should emerge from the cacophony of data as did that about the health impacts of smoking after the clouds of vested interests had been dispersed. With the large amount of data needing to be processed, lifecycle assessment generally requires expensive software and a trained practitioner. We can wait for someone else then to come up with the answers, but is there anything we can do to work out our impact ourselves? David Mackay in his book, ‘Sustainability without the Hot Air’ presents a straightforward approach of representing our individual impact in energy terms as kWh/person/day. Whilst this approach does not account for aspects such as finite resource depletion and water, we can achieve much with energy – for example we can make new materials or recycle old ones and desalinate water – so to express everything in terms of energy at least can give us some idea of our level of sustainability. Carbon dioxide may also be used as a measure of greenhouse gas emissions, an impact of general concern, and there are a number of ‘carbon footprinting’ tools available free on the web that can give some measurement of lifestyle impact. Carbon dioxide emission equivalent can be a useful way of expressing heat and electricity consumption in a common unit, although it should be recognised that as a measure of overall sustainability it is somewhat limited, and though there is a majority scientific view that human activity CO2 emissions are having an impact on the climate, views on the degree and nature of the impacts are in flux.
Energy including transport
The energy required to support our lifestyle may be subdivided into the following categories:
- Electricity for lighting and appliances
- Embodied energy in products
To all of these the energy hierarchy may be applied, which is broadly:
- Avoid the use of energy
- Use energy more efficiently
- Renewable energy supply
This can be expressed specifically for transport as the transport hierarchy, which may take the following form:
- Avoid travel
- Use efficient forms of transport
- Use renewable forms of transport
So what does this mean in practice?
Renewable energy is a constrained resource, given in particular the space required to convert it and also the intermittency of generation for most forms which make it challenging to align with demand. Biomass allows control of timing of generation to supply a demand, unlike wind energy for example, but requires large areas of land as it is not a particularly efficient way of converting sunlight to energy, as compared to photovoltaics for example. Biomass can supply a proportion of current base load, but if we are to supply the rest of our demand from renewables we would largely be dependent on intermittent resources. Intermittency can to some extent be addressed through energy storage, but this is currently expensive. Increased interconnection between countries can also smooth intermittency. However to a large extent the accommodation of intermittent renewable energy needs to come from demand management. Therefore not only do we need to think about reducing our demand, but we also need to think about timing our consumption to coincide with availability of power. This can be done through a combination of occupier intervention and automated controls. The question is the extent to which people either want or feel able to time their energy consumption for optimum matching with renewable generation and how much should be automated. The best balance may be for people to have the option of making relatively simple choices, with more complex energy balancing being managed by control systems. This is an example of where there needs to be attention given to an effective interface between human behaviour and engineering solutions.
A large proportion of our energy consumption in the UK is for heating. Biomass heating can make a significant contribution, but with the constraints on biomass production, it is unlikely that this will meet all of our heating needs, in particular given the opportunities for heat consumption reduction in existing buildings are limited. Therefore for renewable heating it seems likely that some form of electric heating will be required, through heat pumps for example. This gives the advantage of allowing extensive buffering of the intermittency of renewable energy generation, giving the thermal inertia that is typical in heating buildings – building temperature does not generally change quickly if heating is switched off for a while, whereas for many electrical appliances such as televisions, the impact of a power dip can be significant. In terms of lifestyle choice heating systems may be automated, but decisions need to be made as to the timing of heating and the temperature settings. In general we need to get used to far lower levels of heating and compensate by wearing more clothing indoors in winter, for example.
Conventional ways of powering transport cannot be easily sustained, for similar reasons as given for heating above. A switch from fossil transport fuels to biomass transport fuels is limited due to biomass being a constrained resource, and with current agricultural technology and availability of suitable land we would be unable to satisfy all our transport requirements through biomass. Therefore it seems likely that there will be a need for electricity in some form to be used for transport. This may be used in conjunction with batteries or to synthesise a hydrocarbon or produce hydrogen for powering transport, but whichever way, transport presents an opportunity for the buffering of intermittency of renewable electricity generation.
Energy storage is a technology area for which there is room for much development. In general it is currently not economically viable apart from for niche circumstances, but with increasing volatility in energy prices and advancements in technology this is likely to change.
With the availability of feed-in tariffs (FiTs) and the Renewable Heat Incentive (RHI) to householders in the UK, there is increased interest in domestic generation, but is small scale generation connected directly to a dwelling a good idea or is it better to focus on large scale renewable energy generation? It is often suggested that building-integrated renewable energy generation is more efficient than remote large-scale generation for the reason that it does not suffer so much from distribution losses. However this benefit is often outweighed by the increased efficiency of large scale generation due to both the relationship between efficiency and scale and also the availability of more favourable resource remote from the built environment. It may be that for thermal generation, co-location of the generation with the building using the power allows the implementation of combined heat and power (CHP), using the waste heat from electricity generation to heat buildings. However an appropriate scale of CHP should be adopted to give an electrical efficiency that will allow the best use of fuel and satisfactory economic performance. This generally means not limiting the approach to energy generation on a single building, but serving a mix of buildings.
It is clear that with significant constraints on sustainable energy supply it is fundamental that attention is given to energy consumption reduction. Whilst much of this can be achieved through reduction of unnecessary consumption without a notable impact on quality of life, it is likely that some sacrifices will need to be made and getting people to accept this will be a major challenge. It is therefore critical that the societal dimension of sustainability is understood and delivered upon.
Finite resource depletion and waste management
In the same way that we may think in terms of an energy hierarchy and transport hierarchy, we may also consider the waste hierarchy. This may be expressed as:
- Avoid generating waste
- Re-use of waste
It is often thought that if we recycle our waste then we do not need to worry further about it. However the energy use of recycling may be significant and indeed, in certain circumstances, actions 3 and 4 above may be interchangeable in that, in environmental terms, it may be preferable to generate energy than recycle in considering the energy required for recycling. Increasingly thought is being given to treating waste as a resource rather than something to be disposed of. It is therefore helpful to think in terms of the lifecycle of a material with more than one use. For example wood may be used in construction with a view to it later being used as a fuel for energy generation. This is consistent with the emerging way of thinking referred to as the ‘circular economy’. In the context of waste it can be demonstrated that whilst a zero-waste economy is thermodynamically impossible, there is much to be gained by focusing on product design and use, such that there can be a cyclic relationship between systems thereby minimising waste – this may be a more helpful way of viewing waste management than the waste hierarchy.
So much of the production of our machines and materials depends on the extraction of substances from the earth’s crust that that are not replenishable within the timescale of human existence. There is therefore a case for the increased production of materials from sustainable biological resources. An understanding of product lifecycle is however critical since the production of biologically derived materials may require significant energy or even chemical input. For example it may be that the production of cotton, with its use of fertilisers and pesticides might end up requiring more energy and polluting more than the production of certain artificial fibres.
The availability of water suitable for drinking is of significant concern even in countries like the UK where flooding is not uncommon. Increasing population, associated food production and industrial processes are putting significant pressure on our water resources. As for energy and waste, the approach towards the sustainability of water may also be expressed as a hierarchy:
- Avoid the use of water
- Use water more efficiently
- Renewable sourcing of water
It is often thought that local supply of water, for example through rainwater harvesting on buildings, is preferable to large scale water production. However, as for energy generation, it is often the case that centralised water treatment is more efficient than local water treatment even when taken into account distribution requirements.
In some parts of the world, such as Australia and China, there is extraction of fossil water reserves that cannot be replenished. Clearly seawater is plentiful but desalination has a major energy penalty. However it may be that desalination has a role to play in inter-seasonal energy buffering. Renewable energy resource generally not only varies diurnally, but also annually. Electricity storage is even a challenge economically when applied to buffering diurnal variations, but buffering of seasonal variations with electricity storage is currently untenable. Converting this energy to desalination of water and storage of potable water inter-seasonally may however be a worthwhile consideration for some locations.
Role of engineers in facilitating sustainable lifestyles
Engineers traditionally solve problems. For example, if we need to accelerate the industrialisation of a nation or area, engineers generally provide infrastructure, facilities and means of exploiting the area’s natural resources for economic gain. For increased sustainability it is necessary to do more with less or preferably facilitate a solution that requires no additional manufacture or construction – a ‘no build solution’. Considering transport for example, we either develop more energy efficient means of moving goods or people – doing more with less, or we put people closer to their jobs so they do not need to be moved – the ‘no build solution’. The latter is not always an option; for example we may need to grow more food for an expanding world population. The ‘more with less’ option can include a variety of factors such as improved provenance, better use of fertilisers, less energy in the sowing, growing and harvesting processes and better storage and distribution. If all efforts in these and other areas do not keep pace with population growth, or if that growth uses agricultural land, the only ‘no build solution’ may be to control population. This may appear initially untenable, but if we do not do it deliberately, nature may do it for us.
This illustrates that not all sustainability problems have technical solutions. At some point in the timescale of human development we must mature from always wanting more, at the expense of our future, towards a state where sustainability means just that: living a lifestyle which we can maintain indefinitely. In financial terms we must make the transition from living off the capital to living off the interest. Individual citizens have a part to play in making lifestyle choices but engineers can help, not only through technical solutions, but also through helping develop a framework whereby the need for consumption can be reduced in line with the hierarchies presented above. This can be, for example, through combination or co-location of different systems such as energy, transport, water and waste to reduce the need for duplication of process and unnecessary activity.
With this article an attempt has been made to give an introduction to the various aspects that need to be thought through in moving towards a sustainable lifestyle. It is intended that subsequent articles will focus on specific aspects and explore practical considerations more fully. As individuals we need to consider what influence we can have over our own lifestyles and also influence those in Government who implement systems that make this easier for us. For those of us who are engineers we need to consider what we can do to allow people to live more sustainably.
We all need to think globally and not just consider equations within our own ways of life. For example we might think that because we are generating renewable energy on our land that it would acceptable to consume more energy. This is an example of what is sometimes known as the ‘rebound effect’, the Khazzoom-Brookes postulate or ‘Jevons Paradox’. Not only might this result in our own impact not improving with the introduction of renewable energy, but it also undermines the potential for sustainable energy consumption to be achieved globally, due to renewable energy being constrained resource. Many projects that appear to be sustainable within the boundaries of the project, for example with renewable energy generation balancing demand on site, are not necessarily replicable globally. We need to develop ways of measuring our impact and making informed decisions about appropriate action.
Figure 1 encapsulates the transition towards sustainable resource consumption and the division of responsibility in making it happen. The relative size of the sections and their interrelationships will depend on a range of factors including physical constraints, economics and considerations of human behaviour. Subsequent articles will explore what is most desirable and practical. Views on this subject are welcome from readers, and if posted on the forum will be taken into account for forthcoming articles.
1Electric hand drying