Trevor Young

CONSTRUCTING A FARM LEVEL INDICATOR OF SUSTAINABLE AGRICULTURAL PRACTICE

Abstract There has been a concerted effort since the Rio Earth Summit to construct indicators to monitor progress towards sustainable development. This has included indicators of sustainable land management, land quality indicators and indicators of sustainable agriculture. It is argued in this paper that the design and use of such indicators can be extremely useful in that they force those involved in the discussion of sustainability to identify the key aspects of sustainable agriculture and to assign weights to them. In this process the discussion of sustainability may be coaxed from the realms of general discussion and abstraction to a more operational context, and ultimately to the discussion and classification of actual practices and farms. To this end, a farm-level indicator of agricultural sustainability, based on patterns of input use, is constructed for a sample of 80 organic and 157 conventional producers in the UK. The paper serves to highlight some of the conceptual issues, examines some of the technical issues and choices associated with indicator construction, and informs discussion of the relationship between organic production and agricultural sustainability.

The impact of BSE on the demand for beef and other meats in Great Britain

Indices of media coverage of BSE are incorporated in a dynamic AIDS model of meat demand. The publicity which BSE has received is found to have had significant effects on the allocation of consumer expenditure among the meats. A short-run impact has been identified which accounts in large part for the discernible drop in the market share of beef in the early 1990s. And more important, there also appears to be a significant long-run impact of BSE, which by the end of 1993 has reduced the beef market share by 4.5%.

Modelling the adoption of organic horticultural technology in the UK using Duration Analysis

Duration Analysis, which allows the timing of an event to be explored in a dynamic framework, is used to model the adoption of organic horticultural technology in the UK. The influence of a range of economic and non-economic determinants is explored using discrete time models. The empirical results highlight the importance of gender, attitudes to the environment and information networks, as well as systematic effects that influence the adoption decision over the lifetime of the producer and over the survey period.

The development of and prospects for organic farming in the UK

Abstract The organic sector in the UK is booming with the largest ever wave of farm conversions underway. Consumer demand is currently growing faster than supply. The evidence regarding the factors that have been critical, now and in the past, in causing producers to establish organic systems is reviewed. This review draws on the authors’ own work as well as that of other researchers in Europe and the USA. In the second part of the paper we report on a recent study of the factors that prompt organic producers to abandon registered organic production. This analysis is based on a survey of producers, formerly registered with the Soil Association, who have left the scheme since 1990. Finally, the paper considers the current policy regime with respect to organic farming, the scope for the continued growth of the sector and the debate regarding the design of future policy.

Factors Influencing the Adoption of Sustainable Agricultural Technologies: Evidence from the State of Espı́rito Santo, Brazil

Abstract A dynamic econometric framework (duration analysis) is used to analyze the determinants of farmers’ decisions on whether or not to adopt low-external-input and sustainable agriculture (LEISA) technology. A wide range of potential determinants (both economic and non-economic) are considered. Our results suggest that the probability of a farmer adopting this technology increased if the farmer was more integrated with farmers’ organizations, had contacts with nongovernmental organizations, was aware of the negative effect of chemicals on health and the environment, could rely on family labor, and had a farm located in an area with better soil conditions. On the other hand, the probability of adoption was reduced by increases in farm size. In addition, time-varying economic variables outside farmers’ control were found to be significant determinants of adoption and the rate of diffusion. Changes in relative prices were particularly influential. Specifically, the diffusion of sustainable technology accelerated when declining output prices squeezed agricultural profit and many farmers faced difficulties in buying external inputs. Similarly, when labor became relatively cheap in periods of economic crisis, low-external-input practices became a more attractive option for family smallholdings.

Estimating Irreversible Supply Functions

The question of specifying and estimating irreversible functions has arisen most frequently in the context of agricultural supply. Theoretical arguments in favor of an asymmetric response of output to rising and falling prices were advanced by Johnson. A number of authors have attempted to estimate such relationships (Hartman, Houck, Saylor, Tweeten and Quance 1969). In this paper, we argue that the general lack of success of these studies is the result of a misunderstanding of the nature of the supply irreversibility. An alternative method of segmenting the price series is proposed and an empirical example presented.

Entry of foreign banks in the People's Republic of China: a survival analysis

This study uses survival analysis to examine the factors determining the decision of a foreign bank to establish a branch in the PRC. Bank size and international diversification are found to have a significant positive impact on the probability of entry. Banks from Asia have particular cultural and locational advantages in this context and are found to be more likely to enter this market. Market conditions in the host economy, exemplified by an improved political environment and increasing levels of international trade, are also found to be significant determinants of the timing of entry. Access to Chinas banking sector will increase upon entry to the WTO and again cultural links and location are likely to play a key role for foreign entrants, particularly for those operating in local currency markets.

Investigation of polycrystalline silicon deposition on glass substrates

Abstract Borosilicate glass has been chosen as substrate for solution growth of silicon due to its potential role as the superstrate of a solar module. Several approaches has been used to deposit polycrystalline silicon layer from solution on to glass substrates, namely, silicon particle seeded growth, growth on α-silicon coated glass substrates and growth on bare glass from the solutions containing Al or Mg. Large grain polycrystalline silicon crystals have been grown on glass substrates previously seeded by silicon particles. Continuous silicon thin films have been deposited onto α-silicon coated glass substrates. For the third approach, impinging growth of silicon layers has been obtained on sandblasted glass substrates from solutions containing Al and Mg at temperatures below 600°C, if the concentration of Al and Mg in the solution and the contact time between the solution and the substrate are appropriately adjusted. Large grain continuous silicon thin films with an area of 10 cm2 have also been groown on glass substrates at temperatures around the softening points of the glass.

Optical analysis of perovskite/silicon tandem solar cells

Semi-transparent perovskite solar cells have significant potential as the top cell in a tandem structure with silicon (Si) or copper indium gallium selenide (CIGS) as the bottom cell. The efficiency of such tandem cells depends on careful light management and optical design of the device. Here, using the transfer matrix method, we report a detailed optical analysis of the absorption distribution, parasitic absorption and reflection losses in various semi-transparent perovskite solar cell structures and their impact on tandem cell efficiencies. The optical properties of some key layers of a semi perovskite cell are measured and modelled to facilitate the optical analysis. It is found that the encapsulation glass and the absorption in the transparent conductive electrode have a huge impact on the tandem efficiency. The tandem efficiency limit is also calculated to present the design of a two-terminal current-matched tandem device required to achieve 30% conversion efficiency. This work provides directions for further improving the power conversion efficiency of perovskite/Si tandem cells.

Rear surface passivation of high‐efficiency silicon solar cells by a floating junction

The passivated emitter, rear locally diffused (PERL) cells, fabricated in our laboratory, reach an efficiency of 24.0%, the highest value for any silicon‐based solar cell under terrestrial illumination. In an attempt to improve the rear surface passivation, which is usually obtained by a thermally grown oxide, we add a floating (i.e., noncontacted) p–n junction at the rear surface, resulting in the passivated emitter, rear floating p–n junction (PERF) cell design. Although these cells exhibit record 1‐sun open‐circuit voltages of up to 720 mV, their efficiency is degraded by nonlinearities (‘‘shoulders’’) in the logarithmic I–V curves. In order to understand and manipulate such nonlinearities, this paper presents a detailed investigation of the internal operation of PERF cells by means of numerical modelling based on experimentally determined device parameters. From the model, we derive design rules for optimum cell performance and develop a generalized argumentation that is suitable to compare the passiv...