Green Metrics, Clean Metrics

A Carbon Footprinting Standard

We finally have the British standard for carbon footprinting of goods and services known as PAS 2050. It builds on existing life-cycle assessment methods (ISO 14040 series) to specify rigorous and consistent requirements for assessing life-cycle GHG emissions of goods and services. I'll highlight some of the more interesting points from the specification:

• Timing of emissions:
  • Production and distribution emissions are modeled as a single release of emissions at the beginning of the 100-year assessment period.
  • If the use and disposal phase emissions occur beyond the first year, a weighting factor is applied to model the average time the emissions are present in the atmosphere during the 100-year period. This is a significant improvement over the static, time-independent calculation of emissions.
• Included:
  • All emissions within the system boundary that can potentially contribute more than 1% of the total life-cycle GHG emissions.
  • Carbon storage in products, such as biogenic carbon stored in wooden furniture, using a weighted average time of storage or uptake emissions.
  • Non-CO2 GHG emissions, such as CH4 and N2O, from products containing biogenic carbon as well as from livestock and soils (the last two based on the highest tier approach set out in the IPCC Guidelines or employed in the country where emissions are produced).
  • For agricultural crops, GHG emissions arising from land use change. This appears to be a stringent requirement, requiring worst-in-class data when the land use history is unknown.
• Excluded:
  • CO2 emissions from biogenic carbon sources, including when a product containing biogenic carbon degrades.
  • GHG emissions from the production of capital goods, such as machinery, equipment and buildings. These input flows to the system are basically "cut off" and removed. No support for a hybrid LCA approach.
  • Carbon sequestration in agricultural soils or carbon release from soils due to tilling practices, crop types, use of compost and other soil management. This is potentially a big omission given the amount of carbon stored in soils.
  • Human or animal labor.
  • Consumer transport to point of purchase.
  • Employee transport to/from place of work.
• Data quality:
  • Primary activity data must be collected from processes owned/operated/controlled by the organization doing the carbon footprinting. If that organization contributes less than 10% of the upstream GHG emissions to the next downstream user, then the primary data requirements fall on the first upstream provider that does contribute 10% or more of the emissions. This can be a very difficult requirement for small companies and retailers who are not in a position to ask their big suppliers for internal operational data.
  • For secondary data, PAS-compliant data gets preference as expected. There seems to be some provision for using secondary data when primary data is not available, but it is not clear if that would prevent a company from claiming compliance with the standard.

So, some coverage of dynamic carbon footprinting, no support for hybrid LCA, no consideration of carbon sequestration in or release from soils, tight system boundary (this enables a "streamlined LCA" approach), and strict data quality requirements. All in all, a good starting point, which I hope will evolve into a more complete specification. This may well become the default global standard for product/service carbon footprinting. The GHG Protocol has an independent effort focused on product life-cycle emissions and corporate scope 3 emissions -- it might be more productive for them to converge with PAS 2050 on the product life-cycle emissions.

Kumar Venkat

Green Deal and Green Buildup

An article in Time magazine suggests that "a recession could be the first step to a truly green economy". There is no question that we need a strong catalyst to start developing a green economy -- not just for environmental reasons, but also to replace the rapidly vanishing blue-collar jobs. Perhaps the current economic metldown and prospects of a long recession can be seen as an opportunity to make a paradigm shift. The article talks about a Green Deal -- a modern version of the New Deal consisting of smart subsidies for alternative energy and green buildings, retraining workers for green jobs, more research in clean tech, and a carbon tax -- and making 'green' a fundamental economic choice as opposed to just a personal lifestyle choice.

Along the same lines, Thomas Friedman in the New York Times says "we can't afford a financial bailout that also isn't a green buildup."

Kumar Venkat

GHG Emissions: Production vs. Use Phase

A recent paper in Environmental Science & Technology gives a nice breakdown of typical life-cycle GHG emissions of conventional vehicles, hybrid electric vehicles, and plug-in hybrids for specific operating conditions. The production emissions are about 35 g of CO2-eq/km traveled, for all of them (slightly more when battery production is included for the hybrids). The use phase dominates, ranging from 145 to 240 g CO2-eq/km (the higher emissions coming from conventional vehicles).

A life-cycle assessment of apparel products shows that 73% of the life-cycle energy use for a pair of men's polyester trousers is due to washing, drying and ironing. Similary, 80% of the energy use in a pack of men's cotton briefs is a result of the use phase (cotton uses more energy in the use phase per unit weight).

Life-cycle emissions for products that last some years and use energy throughout that period are likely to be dominated by the use phase (products such as cars, applicances, clothes, etc.). So, for consumers, switching to hybrid vehicles and purchasing fabrics that consume less energy in washing/drying are all critical steps. However, given the huge amounts of manufactured products in the economy, production and distribution emissions are still important to quantify and optimize from a manufacturing perspective. CO2 emissions for the industrial sector (from fossil fuel combustion) are significantly higher than for the residential sector in the US and second only to transportation.

Kumar Venkat

Carbon Footprinting as a Process Characterization Tool

While product eco-labeling is one of the applications of carbon footprinting, I have argued previously that carbon footprinting can and should be used as a life-cycle process characterization tool that can reveal significant opportunities for optimizations. In that sense, using carbon emissions as a performance metric is analogous to the use of 'time' as a key metric in lean systems. I want to mention two specific examples from recent projects where optimization opportunities were revealed by a footprint analysis -- both are from the food industry, but the idea is by no means limited to any particular industry.

• In a carbon footprint analysis of a soymilk product, we found that most of the transport emissions occurred after the product was manufactured, even though almost all of the ingredients were transported a long way from other countries. It turns out that soymilk is more than 90% water, and all that water was added at the final production step. So, for a given quantity of final product (such as a half-gallon package), transporting all that water from the final production facility to the distribution centers and retail stores dominated the overall transport emissions. Minimizing transport distance after final production -- for example, by making the final production more regional and closer to the points of sale, even if most ingredients are still imported -- would be one way to reduce the footprint and make the process leaner/greener.
• A carbon footprint analysis of ready-to-eat cut fruit that is packaged in plastic containers (with no need for refrigeration) revealed that the fruits were cut by the suppliers in one country and shipped frozen to a packing facility in another country in the same continent by ocean and road. Initial freezing of fresh cut fruit is a highly energy intensive process, which alone accounted for about 30% of the product life-cycle emissions. Eliminating the need for freezing, by locating the packing facility closer to the fruit production (even if this doesn't reduce the total transport distance to consumers), would significantly reduce energy use and carbon footprint.

Kumar Venkat

Time-Limited Carbon Sequestration in Soils

A recent paper in Waste Management & Research opens up a discussion that may become increasingly relevant in mitigating climate change. As the authors point out:

• More than twice as much carbon is held in soils as in vegetation or in the atmosphere, so understanding the build-up of organic carbon in soil is important.
• The loss of organic carbon in soils has been one of the major consequences of industrial agriculture.
• Composted organic fertilizers offer a huge opportunity to lock up considerable amounts of carbon while restoring soil fertility and health.

Application of organic matter on a regular basis increases carbon content in soils, but at some point the system reaches a steady-state where the mineralization of organic carbon into CO2 offsets the annual accumulation of organic matter. The authors argue that there is considerable potential for a time-limited carbon sequestration in soils in the short/medium term as the system moves toward a stead state. This is important because a short-term reduction in net GHG emissions buys us time and can be very valuable while we move toward long-term emission reductions elsewhere in the economy. In addition, as organic soil amendments replace synthetic fertilizers, the slower release of nitrogen make it less prone to producing N2O. (According to the IPCC, about 1.25% of readily-available nitrogen from fertilizers turns into N2O through denitrification/nitrification. N2O has a global warming potential of 310 relative to CO2 -- so any reduction in N2O is a big deal.)

Unfortunately, we lack a good methodology to take into account these dynamics and the time profile of emissions (see my earlier post on dynamic carbon footprinting). Current life-cycle assessment methodologies perform a static analysis, ignoring the dimension of time. This may be fine for modeling thermal processes which lead to CO2 emissions immediately, but not for biological processes that occur over decades or even centuries.

Kumar Venkat

Carbon Footprint Labeling

A quick look at some of the carbon footprint labeling efforts around the world:

• Japan: The trade ministry is working closely with 30 companies on a standardized carbon labeling scheme. Food and beverages are among the initial products to be labeled.
• UK: Tesco is testing carbon labels on its own-brand products (including food/beverages), and a standard is being developed by Carbon Trust, Defra and BSI.
• Europe: Multiple supermarket chains and others in the food industry are moving toward carbon labeling, some following the emerging UK standard.
• US: A lot of interest and some independent initiatives by Wal-Mart, Bon Appetit, others -- we've been involved in some of them, directly or indirectly -- but no large-scale efforts or move toward standards. The US is clearly lagging other advanced economies in systematically quantifying environmental performance. Before we can optimize performance, we need to quantify the current state. My best guess is that we'll be following the UK standard by next year.

Kumar Venkat

Virtual Water

Virtual water is much like carbon footprint. It is the total quantity water used in the production of any product or service. Some shocking figures:

• A cup of coffee requires 140 liters of water to produce
• A single hamburger has a 'water footprint' of 2400 liters -- not to mention large GHG emissions

• The average American consumes 7000 liters of virtual water every day, more than three times the Chinese average

Water production and processing release significant GHG emissions, and global warming is straining fresh water supplies. All inextricably linked.

Kumar Venkat

Glass, Plastic or Aluminum?

A recent article on Environmental Leader argues the PET is environmentally superior to glass or aluminum as a food/beverage packaging material. Our recent work confirms that PET has significantly lower life-cycle GHG emissions compared to glass or virgin aluminum. For a typical 12 oz container, here are some sample GHG emissions figures based on materials and fabrication (assuming container weights of 365 g for glass, 54 g for PET, 40 g for aluminum):

• Glass (virgin): 256 g of CO2-e

• Glass (80% recycled content): 217 g of CO2-eq

• PET (virgin): 139 g of CO2-eq

• Aluminum (virgin): 521 g of CO2-eq

• Aluminum (100% recycled content): 37 g of CO2-eq

So, unless the aluminum includes mostly recycled content, PET would be the best choice from a carbon footprint perspective. When transportation is factored in, glass becomes even less attractive because of its weight. Both aluminum and glass production require very high temperatures and are therefore very energy intensive.

Kumar Venkat

Sustainability in big emerging economies

On my current visit to India, I've been looking at everything through my "sustainability lens". I am not sure if India is really representative of most big emerging economies, but my guess is that it is not very different from China when it comes to sustainability.

The first thing that strikes an observer is that green labels and practices -- such as organic, local, reduced packaging, recycling, low emissions, low carbon footprint, renewable energy, etc. -- are largely absent from public discussion. There are occasional newspaper articles, but both consumers and corporations are focused on other things: quality, cost, convenience. This is not very different from the state of affairs in Western countries just a decade ago. Given the huge numbers of people that are just short of becoming big consumers in India -- and the money to be made by selling to them -- my best guess is that sustainability is unlikely to be front and center in public consciousness for quite a long time.

Government is not leading the way with policy initiatives, so it all comes down to motivating the private sector to take the lead. I believe that any immediate sustainability solutions for India (and possibly China as well) would need to include cost-reduction and profit-making at the core, relying more on the market and less on subsidies, tax breaks and the like. The low cost of labor in these parts might be a big advantage in implementing these solutions. Just looking around, some possibilities come to mind immediately:

• Organized plastic and paper recycling --  segregation/collection (from homes/businesses), state-of-the-art processing, reuse in new products. Increasing cost of raw materials should make this viable. A success story: Bangladesh already has a network of 3000 small factories that are exporting 20000 tons of recycled PET flakes.
• Biodiesel production from used vegetable oils, animal fats and non-edible oil seeds, without consuming edible foods or converting agricultural production. Given the soaring demand for diesel in India and increasing prices (one of the reasons is the increasing use of private diesel generators to offset power outages), an alternative fuel from waste products might be profitable while reducing net GHG emissions. There are some biodiesel plants in operation in India, but the fuel is not widely known or used at this point.
• Small-scale, solar energy systems that can be installed on roofs, possibly off-grid initially. Given the frequent power outages in India and the big part of the population that still doesn't have electricity, something like this is overdue. The cost of solar cells is still an obstacle, but the economics may start making sense in a few years as the $1/watt barrier is breached on a large scale. Government subsidies may be needed to offset capital costs for consumers/businesses, but may turn out to be cheaper than building expensive new coal/gas/nuclear plants -- not to mention lower life-cycle GHG emissions.

Kumar Venkat

Production location and carbon footprints

How does the location of production influence a product's carbon footprint?  Transport to the consumption location is certainly one factor, but what is often overlooked is that the production emissions may vary depending on where it is done.

If the finished product (or the components/ingredients used in production) must be air-freighted, then it is a good bet that air transport distances will heavily influence the final carbon footprint -- this is particularly true for air-freighted food products, where transport emissions can far exceed production emissions. On the other hand, rail and ocean transport are quite benign from a carbon perspective, even with refrigeration added. Road transport can be a critical factor if the production emissions are relatively small -- as in the case of many fruits, vegetables and grains. In one analysis we did concerning transporting dry food ingredients (such as dry beans or grains) from China and the US mid-west to the US west coast, the Chinese imports had the lower carbon emissions. For ocean transport from China to the US, the critical transport links are actually the road segments on either end, and not the long ocean segment that first comes to mind.

If older technology is used in overseas production, for example, then the production emissions per unit product can easily be higher overseas. Even if the same state-of-the-art technology is used at the overseas location, the actual emissions will depend on the fuels and electricity sources used. Here are average CO2 emission factors for energy production in selected countries (2005 data from IEA):

• China: 2.95 t CO2/toe (metric tons of CO2 per 42 GJ)
• India: 2.14
• Brazil: 1.57
• Mexico: 2.21
• France: 1.41
• UK: 2.27
• US: 2.49
• Japan: 2.29

This shows a variation of more than 2x between the best (France) and the worst (China). One big reason: France uses nuclear plants for about 80% of its electricity, and China depends on conventional thermal power plants (dominated by coal) for 74% of its electricity. In Brazil, which is second best in the above list, hydro-power supplies 83% of the electricity.

A related note: Textile and apparel production in China is exacting a heavy environmental toll there. Chinese companies reportedly dump untreated waste water into lakes and rivers. Proper wastewater treatment will add to the product's carbon footprint (US average: 742 Kg of CO2-eq/million gallons of wastewater treated). Prices in the US may be artificially low because we are not paying the costs of pollution for imported products. A VP at Liz Claiborne says the environment is the new frontier after labor issues in overseas production.

Kumar Venkat