5.4.8.1Sub-category description -
The use of mercury in various types of batteries has been extensive and it has been among the largest product uses of mercury. Mercury has mainly - or perhaps solely - been used in primary (that is non-rechargeable) batteries.
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Mercury is used in high concentrations (about 30-32% w/w) in mercury oxide batteries (sometimes called zinc-mercury batteries), where mercury oxide serves as the positive electrode in the battery. These have probably mainly been sold as button shape cells in the west, but also in larger cylindrical and other shapes. Marketing of mercury oxide batteries is now severely restricted in several countries, while some specific uses may still be exempted (for instance military uses in some countries). In the USA, for example, mercury-oxide batteries are now prohibited, but were previously used in transistorized equipment, hearing aids, watches, calculators, computers, smoke detectors, tape recorders, regulated power supplies, radiation detection meters, scientific equipment, pagers, oxygen and metal monitors, and portable electrocardiogram monitors (US EPA, 1997a).
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In the following other battery types, mercury has served as reaction modifier, preventing gas development (and thus breakage) during use of the battery, and a corrosion inhibitor (US EPA, 1997a).
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Earlier, alkaline cylindrical cells on the European market had mercury concentrations of up to around 1%. Due to environmental restrictions on large western markets, mercury consumption with cylindrical alkaline batteries decreased, however, and most global battery brands are now produced without intentionally added mercury content. However, some nationally or regionally traded brands of alkaline batteries with mercury added, still exist.
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Button cell shaped batteries of alkaline, silver oxide and zinc/air types still contain mercury in most cases (at concentrations up to around 1% w/w).
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Other battery types are not considered to contain mercury today. Note that besides plain battery sales, batteries may be imported and exported in substantial amounts in the package of other products like electronics, toys, greeting cards with sounds etc.
5.4.8.2Main factors determining mercury releases and mercury outputs
Table 5 149 Main releases and receiving media throughout the life-cycle of batteries with
mercury
Phase of life cycle
|
Air
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Water
|
Land
|
Products
|
General waste
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Sector specific treatment/
disposal
|
Production
|
X
|
x
|
x
|
X
|
|
x
|
Use
|
|
|
|
|
|
|
Disposal
|
X
|
|
X
|
|
X
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X *1
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Notes: *1 Separately collected batteries containing mercury (or categorized under sorting as such)
may be disposed of in specially secured landfills;
X - Release pathway expected to be predominant for the sub-category;
x - Additional release pathways to be considered, depending on specific source and national situation.
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The workplace procedures in battery manufacture, particularly for mercury oxide batteries, and product reject rates, may be an important factor determining the extent of releases.
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Note that many countries do not have domestic battery production, but rely on imports.
ii) Disposal -
The actual mercury concentrations in the batteries supplied is of major importance for the tonnage of mercury released from this product category.
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For the category as such, the consumption of mercury oxide batteries is of particular importance, because of the relatively high mercury content.
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Besides the mercury content, however, the existence and efficiency of battery collection schemes, as well as the general waste management pattern, are the most important factors influencing mercury releases from batteries. The distribution of the mercury in disposed batteries to receiving pathways is highly dependent of the waste management practice in the country in question.
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In some countries parts of the used batteries are collected for safe handling of the mercury (and cadmium in other types) and possibly recycling. From North European experiences collection rates of about 50% are considered high, and in many cases less is collected, even when considerable information and collection efforts are made. Generally, separately collected batteries are expected to be deposited with a higher degree of safety than household waste. Recycling of batteries with mercury is probably not a widespread procedure today, though more extensive recycling of battery materials is under consideration in some countries.
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Even in countries with separate battery collection, major parts of the consumed batteries are disposed of with general household waste. For batteries in wastes lead to protected landfills, parts of the mercury will be released only slowly as the encapsulation is degraded, by gradual evaporation to the atmosphere, with slow leaching to waste water (or the ground water, if no membrane is used under the landfill), and perhaps ultimately in larger scale if excavation works occur (or even climatic/geological changes). See the description of landfills/deposition in section 5.9. In cases of uncollected, diffusely lost waste, or informal, un-protected waste dumps, the losses occur directly to land. The actual evaporation or bio-availability of the contained mercury may be delayed several years or even decades, because the degradation of the battery encapsulation is expected to happen slowly.
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For batteries in wastes that end up in waste incineration, some of the mercury will be released to the atmosphere when incinerated, while other parts will remain in the solid incineration residues, and if applied, in flue gas cleaning residues, and subsequently deposited in landfills or other deposits, as described in section 5.8. In case of informal waste incineration, parts of the mercury will evaporate and be released to the atmosphere, while other parts will stay in solid residues and be lost to land.
5.4.8.3Discussion of mercury inputs
Table 5 150 Overview of activity rate data and mercury input factor types needed to estimate releases from batteries with mercury
Life-cycle phase
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Activity rate data needed
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Mercury input factor
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Production
|
Metric tons of batteries produced
per year (in the country)
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Kg of mercury released per kg
of mercury in produced batteries
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Use
|
Not needed (Releases negligible)
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Not needed (Releases negligible)
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Disposal
|
Metric tons of batteries supplied
per year a battery lifetime ago *1,
of each battery type
|
Kg mercury per metric ton
of batteries supplied of each type
|
Notes: *1: As a substitute for metric tons disposed of per year. If good estimates of amounts of batteries
disposed of annually exist, these should preferably be used. In times of changing consumption or substitution with mercury-free batteries, the current supply and current disposal will differ from each other.
Production -
Input data on mercury to production of the different mercury containing batteries may not be generally available (except by direct contact to manufacturers). Estimating releases from production as a percentage of the expected mercury content in the battery type in question may be an easier approach for a first estimate. See examples of mercury content and releases from production below.
Disposal -
Mercury input to disposal is the mercury content in the batteries as supplied, multiplied by the number of batteries (of the same type) that are disposed of. Note that mercury disposal with batteries reflects battery mercury content from earlier years (life-times of a few years, depending on type and use). This is important, as mercury concentrations in batteries have changed in the last few years in many countries. If no historical data are available, input numbers from current supply can be used as an estimate.
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Examples of mercury content in batteries per type and region (for data) are presented in Table 5 -151 below.
Table 5 151 Examples of mercury content in batteries in g mercury per kg of batteries, per type and origin of data
Battery type
|
Mercury content in battery (kg Hg/metric ton batteries)
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Country/region for data
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Remarks
|
Mercury oxide (all sizes); also called zinc-mercury cells
|
320
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European Union
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Floyd et al. (2002). The sale of mercury oxide batteries is prohibited in the EU since 2000.
|
Zinc-air button cells
|
12.4
|
European Union
|
EBPA (industry) data as cited by Floyd et al. (2002). Probably mean values, as mercury concentrations may vary somewhat. Mercury content in button cells above 20 kg/metric ton battery are prohibited in the EU since 2000.
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Alkaline button cells
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4.5 - 10 *1
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European Union
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Remarks identical as for zinc-air. 10 kg/metric ton is an older value from Scandinavia (early 1980's).
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Silver oxide button cells
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3.4 - 10 *1
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European Union
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Remarks identical as for zinc-air. 10 kg/metric ton is an older value from Scandinavia (early 1980's).
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Alkaline, other than button cell shapes
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"0" - 10 *1
|
European Union
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Most internal brands are mercury free today, but some nationally or regionally traded brands of alkaline batteries with mercury added, still exist. Non-button alkaline cells with mercury content above 0.25 kg/metric ton battery were prohibited in the EU since 1993, while content above 0.005 kg/metric ton are prohibited since 2000.
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Notes: *1: 10 kg/metric ton is an older value from Scandinavia (early 1980's). Used here to illustrate potential maximum values in battery brands produced with older technology.
5.4.8.4Examples of mercury in releases and wastes/residues Production -
US EPA (1997a) reports an example of one mercury oxide production facility where ventilation air from the production rooms was filtered with particle retaining fabric filters and a charcoal filter, where only 0.1% (1 g/kg) of the mercury used in the production was released to the atmosphere. Presumable, additional amounts of mercury were disposed with used filter material, but this is not reported. US EPA states that this example should be used with caution, because of questionable data quality, and because other battery manufacturers may not have similar emission reduction equipment.
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Another example have been reported from Russia where up to about 27% of the mercury used for mercury oxide battery production was lost during the production, with rejected products and other solid waste (24%), with releases to waste water (2%) and the atmosphere (1%); (Lassen et al., 2004).
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Regarding production of other battery types with much lower mercury content, release percentages could be similar to mercury oxide battery production.
ii) Disposal -
In Denmark an estimated 20-30% of the button cell consumption was collected separately in 2001, while the number was higher - an estimated 30-60% - for larger alkali batteries (Hansen and Hansen, 2003). The remaining parts of the batteries were expected to be disposed of with household waste, of which most ended up in waste incineration. Diffuse, informal waste dumping or incineration is deemed negligible in Denmark. Mercury disposal with batteries reflects battery mercury content from earlier years, therefore mercury oxide still represented the majority of the mercury releases/wastes from batteries in Denmark in 2001 (after mercury oxide sales were prohibited in 2000; Skårup et al., 2003). In the Netherlands collection efficiency across all battery types can be estimated at about 50-70% of the potential, depending on how the collection efficiency is calculated. Collection rates at or slightly below this level were also reported for the (large) municipality of Göteborg in Sweden (based on Hansen and Hansen, 2003). These examples are likely to be among the highest collection rates among current battery collection schemes.
5.4.8.5Input factors and output distribution factors -
Based on the so far compiled examples given above, the following preliminary default input and output distribution factors are suggested for use in cases where source specific data are not available. It is emphasized that the default factors suggested in this Toolkit are based on a limited data base, and as such, they should be considered subject to revisions as the data base grows.
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Table 5 152 Preliminary default mercury input factors, by battery type
Battery type
|
Mercury content in battery (kg Hg/metric ton batteries)
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Mercury oxide (all sizes); also called mercury-zinc cells
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320
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Zinc-air button cells
|
12
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Alkaline button cells
|
5
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Silver oxide button cells
|
4
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Alkaline, other than button cell shapes
|
0.25 *1
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Notes: *1 In EU countries an input factor of 0.005 kg/metric ton should likely be used.
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b) Default mercury output distribution factors -
Note that the output factors for battery production are only relevant for countries with domestic production. Inputs to production are actually the purchases of mercury for the production (of which some is lost during production), but they can be estimated from concentrations in the batteries combined with data on production volumes.
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As regards disposal, quantifications of the actual waste streams in the country will give a more relevant picture of the mercury outputs from this products group. If no such specific quantitative data are available, the distribution factors given in the table below can be used. They are simplifications indicating main trends only, set with the aim of raising the signal that substantial releases may occur to these pathways.
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Note that the table only distributes outputs on direct releases to the environment and the two waste categories mentioned. The final destiny of mercury in wastes depends highly on the national/regional waste treatment scenario and the emission reduction designs involved. See descriptions of these issues in the sections covering general waste incineration (section 5.8) and landfills/deposition (section 5.9).
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Note also that in the default mercury output distribution factors mentioned here, informal dumping or incineration of waste is quantified as direct releases to air, land and water, as relevant. Beware of double-counting, if estimates of mercury releases are also made separately for informal dumping or incineration of waste.
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The estimated mercury outputs to separately collected waste and general household waste from this sub-category contributes to the mercury inputs to landfills/deposits (section 5.9) and household waste incineration (section 5.8).
Table 5 153 Preliminary default mercury output distribution factors for battery production and disposal
Phase in life cycle
|
Default output distribution factors, share of Hg input
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Air
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Water
|
Land
|
General waste
|
Sector specific treatment/
disposal
|
Production *2
|
0.005
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0.005
|
?
|
?
|
0.01
|
Disposal (Actual waste management status in country) *4:
|
|
|
|
|
|
No or very limited separate battery collection. All or most general is waste collected and handled in a publicly controlled manner
|
|
|
|
1
|
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No or very limited separate battery collection. Missing or informal collection and handling of general waste is widespread
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0.25
|
|
0.25
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0.5
|
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Separate battery collection with high collection rates. All or most general is waste collected and handled in a publicly controlled manner
|
|
|
|
0.6
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0.4 *1
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Notes: *1 For button cell batteries, this category will often be special deposits with higher safety guards against
mercury releases;
*2 Outputs in share of mercury amounts in produced batteries. Note that output factors for battery
production are only relevant for countries with domestic production;
*3 High separate collection rates for batteries combined with a high degree of informal general waste
handling is not deemed a relevant combination, as separate collection is often an advanced step
following high general standards;
*4 Mercury inputs to disposal are the concentrations of mercury in the battery types, combined with
disposed amounts of the respective battery types. If annual supply data for a few years earlier
(for the same battery types) are available, they can be used as approximations for disposed amounts.
5.4.8.6Source specific main data -
The most important source specific data would in this case be:
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Consumption of mercury oxide batteries; including imports (also imports incorporated in other products such as toys, greeting cards etc.)
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National or regional trends in mercury concentrations in other batteries (local brands, national/regional regulation etc.); and
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Setup end efficiency of waste management systems.
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Regarding mercury oxide batteries, it is an often encountered problem that national trade statistics are often severely inaccurate, because these batteries are normally sold in small quantities and are therefore very vulnerable to miss-categorization of other batteries in traders' reports to the statistics bureaus. This has consequences, because even moderate reported sales of mercury-oxide batteries may represent mercury turnover exceeding by far the total mercury consumption with other battery types.
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Most likely, batteries are mainly produced in relatively few, larger production plants, and a point source approach to mercury release estimates from production is therefore recommended, where possible.
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See also advice on data gathering in section 4.4.5.
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