School of Biological Sciences, University of Adelaide, PMB 1, Glen Osmond, SA, 5064, Australia.
CSIRO Land and Water, Waite Campus, SA, 5064, Australia.
J Environ Manage. 2017 May 1;192:171-183. doi: 10.1016/j.jenvman.2017.01.049. Epub 2017 Feb 2.
The economics of establishing perennial species as renewable energy feedstocks has been widely investigated as a climate change adapted diversification option for landholders, primarily using net present value (NPV) analysis. NPV does not account for key uncertainties likely to influence relevant landholder decision making. While real options analysis (ROA) is an alternative method that accounts for the uncertainty over future conditions and the large upfront irreversible investment involved in establishing perennials, there have been limited applications of ROA to evaluating land use change decision economics and even fewer applications considering climate change risks. Further, while the influence of spatially varying climate risk on biomass conversion economic has been widely evaluated using NPV methods, effects of spatial variability and climate on land use change have been scarcely assessed with ROA. In this study we applied a simulation-based ROA model to evaluate a landholder's decision to convert land from agriculture to biomass. This spatially explicit model considers price and yield risks under baseline climate and two climate change scenarios over a geographically diverse farming region. We found that underlying variability in primary productivity across the study area had a substantial effect on conversion thresholds required to trigger land use change when compared to results from NPV analysis. Areas traditionally thought of as being quite similar in average productive capacity can display large differences in response to the inclusion of production and price risks. The effects of climate change, broadly reduced returns required for land use change to biomass in low and medium rainfall zones and increased them in higher rainfall areas. Additionally, the risks posed by climate change can further exacerbate the tendency for NPV methods to underestimate true conversion thresholds. Our results show that even under severe drying and warming where crop yield variability is more affected than perennial biomass plantings, comparatively little of the study area is economically viable for conversion to biomass under $200/DM t, and it is not until prices exceed $200/DM t that significant areas become profitable for biomass plantings. We conclude that for biomass to become a valuable diversification option the synchronisation of products and services derived from biomass and the development of markets is vital.
将多年生物种作为可再生能源饲料进行开发的经济问题已被广泛研究，作为土地所有者适应气候变化的多样化选择，主要采用净现值（NPV）分析。NPV 并未考虑可能影响相关土地所有者决策的关键不确定性。虽然实物期权分析（ROA）是一种替代方法，可以考虑未来条件的不确定性和多年生植物建立所涉及的巨额前期不可逆投资，但 ROA 很少被应用于评估土地利用变化决策的经济学，考虑气候变化风险的应用则更少。此外，虽然使用 NPV 方法广泛评估了空间变化的气候风险对生物质转化经济的影响，但很少使用 ROA 评估空间变异性和气候对土地利用变化的影响。在本研究中，我们应用了基于模拟的 ROA 模型来评估土地所有者将土地从农业转为生物量的决策。该空间显式模型考虑了在地理多样化的农业区，在基准气候和两种气候变化情景下的价格和产量风险。我们发现，与 NPV 分析结果相比，研究区域内初级生产力的基本变异性对触发土地利用变化所需的转换阈值有很大影响。传统上认为在平均生产力方面非常相似的区域，在纳入生产和价格风险后，其反应可能存在很大差异。气候变化的影响广泛降低了低中降雨量区土地利用向生物质转变所需的回报率，并增加了高降雨量区的回报率。此外，气候变化带来的风险可能会进一步加剧 NPV 方法低估真实转换阈值的趋势。我们的研究结果表明，即使在作物产量变化比多年生生物质种植更受影响的严重干燥和变暖情况下，在 200 美元/干物质吨以下，研究区域内只有相对较少的区域在经济上可行，而只有当价格超过 200 美元/干物质吨时，才有大量区域对生物质种植有利可图。我们得出的结论是，要使生物质成为一种有价值的多样化选择，就必须同步来自生物质的产品和服务，并发展市场。
