Measurement and Analysis of bioenergy greenhouse gases: Integrating GHGs into LCAs and the UK Biomass Value Chain Modelling Environment (MAGLUE)

为了实现2020年的可再生能源目标，英国将需要生物质，而且数量巨大。DECC希望到2020年增加20-38TWh的生物质发电，这将需要大约1200万-2300万干吨生物质。这是一种巨大的材料，其中绝大多数将作为球团从加拿大和美国进口，并在改装后的燃煤发电厂燃烧。其他进口的液体燃料原料可能包括来自巴西的甘蔗乙醇和来自东南亚的棕榈油。英国并不是唯一想要使用更多生物质的国家。荷兰、比利时、丹麦和瑞典都预计会使用更多木质颗粒，例如，对欧盟未来对木质颗粒的需求估计在2300万吨到8000万吨之间。英国的一家燃煤发电站正寻求每年生产高达1000万吨的生物质。如果英国想要大规模生产生物质能源，很明显，发电商将需要成为跨大西洋木球贸易的主要参与者。在这种需求增加的背景下，生物质能源的使用在环境上是否可持续仍然存在很大的不确定性。任何类型的有管理的土地使用都会招致碳“债务”--碳或其他温室气体在大气中的净损失，从而导致全球变暖。其他温室气体包括甲烷和氮氧化物。但是，要量化一种生物能源作物相对于它可能取代的作物的净影响(有时被称为反事实)，并不直接。这导致了许多来自商业利益集团、环保组织和学者关于土地利用变化对生物能源系统的真实温室气体影响的索赔和反索赔，在这方面仍然存在许多分歧和争议。这里描述的项目旨在解决这个有争议的问题-量化英国和进口生物能源原料不同土地利用向生物能源作物过渡的实际温室气体平衡。我们将部署能够非常快速地测量温室气体的尖端最先进的仪器，以更好地了解在这类系统中可能发生的温室气体排放的动态范围，包括当耕种田地和添加化肥时。在数据收集之后，我们将通过对整个英国和来自世界其他地区的生物质原料进行广泛的地理范围建模来扩展我们的分析。如果我们能够在全球范围内利用现有的天气、土壤和感兴趣作物产量数据的数据集，我们使用的模型应该会奏效。这类系统中的温室气体数据通常被用来制定排放因素，这些因素被输入到碳(或碳当量)成本的全生命周期评估(LCA)中，但过去这些数据往往是未经验证的数据。我们将评估过去数据的质量，并从我们的测量和模型活动中测试排放因素的有效性，以及如何通过我们的工作改进这些因素，包括海外原料。最后，在一个联合项目中，我们开发了一个价值链模型，根据成本、温室气体平衡和土地可获得性的定义，优化英国的生物能源技术选择。我们将运行这一模型，以确定英国温室气体平衡方面的最佳生物能源链，并测试情景(假设问题)，以确定未来有多少进口原料可能是可持续的。

To meet the 2020 renewable energy target the UK is going to need biomass, and lots of it. DECC has an aspiration for an additional 20-38TWh of biomass electricity by 2020 and this will require around 12-23 million dry tonnes of biomass. This is a huge quantity of material, the vast majority of which would be imported as pellets from Canada and the USA and burnt in converted coal fired power plants. Other imported feedstocks for liquid fuels might include Brazilian ethanol from sugar cane and oils from palm oil in Southeast Asia. The UK is not alone in wanting to use more biomass. The Netherlands, Belgium, Denmark, and Sweden all expect to use more, and estimates of future EU demand for wood pellets alone, for example, range from 23-80 million tonnes. One single coal power station in the UK is looking to source up to 10 million tonnes of biomass each year. If the UK wants biomass power on a large scale it is clear that the power generators will need to become major players in the transatlantic wood pellet trade. Against this background of increased demand, there remains significant uncertainty on whether the use of biomass for energy is environmentally sustainable. Any type of managed land use can incur a carbon 'debt' - a net loss of carbon or other greenhouse gases to the atmosphere that contributes to global warming. Other greenhouse gases include methane and the oxides of nitrogen. But quantifying the net impact of a bioenergy crop relative to what it might replace (sometimes called the counterfactual), is less than straightforward. This has led to many claims and counter-claims from commercial interests, environmental groups and academics, on the real greenhouse gas impact of land use change to bioenergy systems, where there still remains much disagreement and controversy.The project described here is aimed at addressing this controversial issue - quantifying the real GHG balance of different land use transitions to bioenergy crops, for both UK and imported bioenergy feedstocks. We will deploy sophisticated state-of-the-art instrumentation that is able to measure GHGs very rapidly, to gain a better insight into the dynamic range of GHG emissions that can occur in such systems, including when fields are ploughed and planted and when fertilisers are added. Following data collection, we will extend our analysis by modelling a wide geographical range across the UK and for biomass feedstock sourced from other areas of the world. The models we use should work if we can utilise available datasets, globally, for weather, soils and yield data of the range of crops of interest.The GHG data in such systems are usually used to develop emissions factors that are inputted into whole life cycle assessments (LCAs) of carbon (or C equivalent) costs, but these in the past have often been unverified data. We will assess the quality of past data and from our measurement and model campaigns we can test the effectiveness of emissions factors and how they might be improved from our work, including for overseas feedstocks. Finally, in an allied project we have developed a value chain model to optimise the technology options for the UK for bioenergy, depending on how cost, GHG balance and land availability are defined. We will run this model to identify the best bioenergy chains, in terms of GHG balance, for the UK and test scenarios ('what if' questions), to determine how much imported feedstock might be sustainable in the future.