E STUDIOS ACADÉMICOS SOBRE PERFILES PROFESIONALES EN TRADUCCIÓN

A risk assessment of the biogas network based on expected site conditions was completed as part of the Feasibility Study (Section 3.2.1) and includes the hazards, consequences and controls relating the installation and operation of the biogas network.

Delivery of the first biogas network would expect to be complete within 18 - 24 months (Phase 2 would be expected to start in September 2013); initially connecting at least 2 rural AD plants, with subsequent plants to follow. A number of potential network opportunities are currently in discussion, located in the North West and the South West regions.

The team are currently in discussion with National Grid for the „biogas network‟ element of the first demonstration unit. The Innovation Fund Incentive (IFI) scheme is a mechanism introduced by Ofgem to encourage GDNs to invest in appropriate research and development activities that focus on technical aspects of network design, operation and maintenance. The principle objective of the IFI is to deliver benefits to consumers, taking a longer term view, by enhancing efficiency in network operating costs and capital expenditure.

National Grid have previously expressed an interest in the biogas network concept, but due to funding eligibility constraints could not be involved in supporting a feasibility assessment. Upon submission of the feasibility report to WRAP, National Grid will also get sight of the

Biogas networks 55 initial findings to provide the evidence that is necessary to confirm their interest in funding and the degree of support. Concerns have been expressed regarding receipt of grant monies for such activities, and potential conflict with RHI or FIT payments – further exploratory work is required on this prior to funding being committed.

To allow this step to take place and discussions to progress, we have not yet completed the detailed project plan for Phase 2. This will be completed within 10 working days and

submitted to WRAP as a separate document, for insertion into or annexing to the feasibility report in due course.

Biogas networks 56

Appendix 1 Manure estimates

Dairy cattle

Various means for calculating manure production are available. DEFRA have previously published broad estimates for manure production rates of dairy cattle using milk yield as a basis for their calculations (Table ).

Table 33 Manure production by dairy cattle20

Milk yield (l/year) Manure production

(kg/day) Manure production (t/year)

<6000 64 23

6000 – 9000 53 19

>9000 42 15

The average milk yield for dairy cattle across the UK for 2011/12 was 7,617 litres per cow21_.

Using this figure it can be estimated that on average, a UK dairy cow produces 53.9kg of manure per day, equivalent to 19.7 tonnes per year.

Meanwhile, a standard method for estimation manure production from dairy cattle was also developed by Nennich et al. using multiple data sets acquired from a variety of US

universities22_{. The study again established manure production rates using milk yields (Figure}

12) and concluded that the following equation can be used for this purpose: Manure production (kg/day) = 0.647 x Milk production (kg/day) + 43.212

Figure 12 Manure production by dairy cattle

Using this equation it can be estimated that UK dairy cows produce 56.7 kg manure per day on average, a figure in line with that calculated using information provided by DEFRA. On account of the transparency provided by the report of Nennich et al. this study used a

20 _{Defra, Guidance for farmers in nitrate vulnerable zones (leaflet 3), April 2009} 21 _{DairyCo, Average Milk Yield, August 2012}

22 _{Nennich et al., Development of standard methods to estimate manure production and nutrient characteristics from dairy} cattle, December 2003

Biogas networks 57 standard estimate for manure production of UK dairy cattle of 56.7 kg manure per day, equivalent to 20.7 tonnes per year.

Collected volumes of manure will vary from farm to farm although it is possible to apply assumptions to estimate the percentage of manure that in would in general be collected from dairy farms23_.

For a 150 head unit the cattle will be housed inside for 6 months during the winter period, for which time all manure can be easily collected. During the outside period it can be assumed that around 30% of manure can be collected during milking and yard movements. Therefore, around 65% of manure produced annually will be collected from a 150 head unit. For a 300 head unit the cattle will also be housed for 6 months. However, during the

summer period the cattle are likely to be housed at night and will result in manure collection rates of around 50% during this period. Therefore, around 75% of manure produced annually will be collected from a 150 head unit.

On account that around 90% of UK dairy farms are of a herd size below 300 head, we assumed a collection rate of 65% for calculating total manure volumes produced at the county level. However, it should be noted that those farms most likely to be interested in involvement with biogas networks schemes are those that are likely to have the higher manure collection rate.

Pig manure

Application of pig manure estimates is more troublesome than for dairy cattle. The data available from DEFRA‟s 2010 agricultural census only accounts for total pig numbers and does not segregate into type (e.g. fattening or breeding), type of feed or age/weight bands, all of which impact upon volumes of manure produced. To provide a standard estimate per head of livestock required analysis of the relevant distribution of pigs in the UK in regards to these factors. The outputs of this analysis is shown in Table and

23 _{Reaseheath Enterprise, Economic viability of farm scale AD biogas generation across Cheshire and Warrington, November} 2010

Biogas networks 58 Table . Distribution and manure production data was sourced from the relevant documents cited in the tables, while conversion of volumes to mass was calculated assuming a density of 1.023 t/m3 _{for pig manure} 24_.

Table 34 Manure production by fattening pigs 25,26

Weight category Proportion

(%) Manure production (kg/day) (Dry- fed) Manure production (kg/day) (Wet- fed) Over 80 kg (finisher) 17 5.85 10.23 50 to 80 kg (grower) 25 4.38 7.31 20 to 50 kg (grower) 29 4.38 7.31 Under 20 kg (weaner) 29 1.43 1.46

24 _{Malley et al., Analysis of nutrients in hog manure by field-portable near-infrared spectroscopy, September 2001} 25 _{Defra, June Survey of Agriculture and Horticulture: Methodology, 2011}

Biogas networks 59

Table 35 Manure production by breeding pigs27 28,

Category Proportion (%) Manure production

(kg/day)

Sows in pig 53 11.25

Gilts in pig 13.5 11.25

Other sows 12.5 5.12

Boars used for service 3 5.12

Gilts for first time breeding 18 4.43

By further assuming that fattening pigs are responsible for 85.5% of the national pig herd - with breeding pigs constituting the remainder20 _{- and that dry-fed to wed-fed fattening pigs}

are distributed in a 2:1 ratio (as estimated by pig nutrionists) it can be calculated that on average 4.39 kg/day of manure is produced per head of pig livestock in England. Clearly, the numerous assumptions made for the calculation mean that this is a very rough estimate but nevertheless, it should be suitable for application for determining manure production by pig farming at a county-level of resolution.

Collected volumes of manure will again vary from farm to farm depending on the housing and husbandry system, but it can be expected that a collection rate of around 90% is generally achievable. This figure was therefore applied to total pig manure production to determine collectible volumes.

27 _{Defra, Guidance for farmers in nitrate vulnerable zones (leaflet 3), April 2009}

Biogas networks 60