Life cycle environmental impacts of generating electricity and heat from biogas produced by anaerobic digestion

AbstractFinancial incentives in many European countries have led to a surge in anaerobic digestion (AD) installations to produce heat and/or electricity from biogas. This paper presents the life cycle environmental impacts of a system producing biogas from agricultural wastes by AD and co-generating heat and electricity in a combined heat and power (CHP) plant. The results suggest that this can lead to significant reductions in most impacts compared to fossil-fuel alternatives, including the global warming potential (GWP) which can be reduced by up to 50%. However, the acidification and eutrophication potentials are respectively 25 and 12 times higher than for natural gas CHP. The impacts are influenced by the type and source of feedstock, digestate storage and its application on land. Using energy crops such as maize instead of waste reduces the GWP owing to higher biogas yields, but eight out of 11 impacts increase compared to using waste feedstocks. If digestate is not used to displace artificial fertilisers, the majority of impacts are higher than from natural gas CHP. Some other bioenergy options have lower GWP than energy from biogas, including woodchip CHP plants. Implications for policy are discussed based on the results of the study

Investigating the importance of motivations and barriers related to microgeneration uptake in the UK

AbstractMicrogeneration technologies such as solar photovoltaics, solar thermal, wind and heat pumps may be able to contribute to meeting UK climate change and energy security targets, but their contribution to UK domestic energy supply remains low. This research uses a best-worst scaling survey of microgeneration adopters, considerers and rejecters (n=291) to determine the relative importance of different motivations and barriers in microgeneration (non) adoption decisions. The most important motivations are earning money from installation, increasing household energy independence and protecting against future high energy costs. Results indicate that the introduction of Feed-in Tariffs has clearly encouraged a new, more financially-motivated, group to install. Financial factors are the most important barriers and of most importance to rejecters is the prospect of losing money if they moved home. The Green Deal was introduced to reduce this barrier, but may instead exacerbate the problem as potential homebuyers are put off purchasing a home with an attached Green Deal debt. The difficulty in finding trustworthy information on microgeneration is also a major obstacle to adoption, particularly for considerers, despite efforts by the government and microgeneration interest groups to reduce this barrier. Self-sufficiency in energy is a more important motivation for those considering or having rejected installation than for adopters. Provision of accessible information and greater emphasis on household self-sufficiency in energy could help improve the uptake

Evaluation of environmental impacts in the catering sector: the case of pasta

n/

Environmental implications of decarbonising electricity supply in large economies: The case of Mexico

AbstractDriven by the security of supply and climate change concerns, decarbonisation of energy supply has become a priority for many countries. This study focuses on Mexico, the world’s 14th largest economy, and considers the environmental implications of decarbonising its electricity supply. Eleven scenarios are considered for the year 2050 with different technology mixes and GHG reduction targets, ranging from stabilisation at the year 2000 level to a reduction of 60–85%. Unlike most energy scenario analyses which focus mainly on direct CO2 or GHG emissions, this paper presents the full life cycle impacts of electricity generation in 2050 considering ten environmental impacts which, in addition to global warming, include resource and ozone layer depletion, acidification, eutrophication, summer smog, human and eco-toxicity. The results indicate that continuing with business as usual (BAU) would double the current life cycle GHG emissions, even if annual electricity demand growth was reduced to 2.25% from the current 2.8%. Switching from the current fossil fuel mix to a higher contribution of renewables (55–86%) and nuclear power (up to 30%) would lead to a significant reduction of all ten life cycle impacts compared to the current situation and up to an 80% reduction compared to BAU

Sustainability assessment of electricity options for Mexico : current situation and future scenarios

The aim of this research has been to identify the most sustainable options for electricity production in Mexico with an outlook to 2050. An integrated methodology for sustainability assessment of different electricity technologies and scenarios has been developed, taking into account environmental, economic and social aspects. The environmental impacts have been estimated using life cycle assessment; the economic costs considered include total capital and annualised costs while social aspects include security and diversity of energy supply, public acceptability, health and safety impacts and intergenerational issues. To help identify the most sustainable options, multi-criteria decision analysis has been used. The methodology has been applied to Mexican conditions for the assessment of both current and future electricity production. The results for the current situation show that on a life cycle basis 129 million tonnes of CO2 eq. are emitted annually from 225 TWh of electricity generated in Mexico. Heavy fuel oil, gas and coal power plants contribute together to 87% of CO2 eq. emissions. Total annualised costs are estimated at US$ 22.4 billion/yr with the fuel costs contributing 54%, mainly due to the operation of gas and heavy fuel oil power plants. A range of future scenarios up to 2050 has been developed in an attempt to identify the most sustainable options. The development of the scenarios has been driven and informed by the national greenhouse gas emission reduction target of 50% by 2050 on the 2000 levels, translating to an 85% reduction from the power sector. The results show that the business as usual (BAU) scenario (with the highest contribution from fossil fuels) is the least sustainable option with the CO2 eq. emissions increasing by almost 300% and the annualised costs by 290% for a projected electricity demand of 813 TWh in 2050. Overall, the most sustainable scenarios are those with higher penetration of renewable energies (wind, solar and hydro) and nuclear power, as in Green, A-3 and C-3. For example, compared to the BAU scenarios, the CO2 eq. emissions reduce by 84%, 89% and 89%, respectively. Although renewable energy based scenarios require high capital costs, the total annualised costs even out over time due to lower fuel costs. The lowest annualised costs are for C-3 scenario, representing a 40% reduction on BAU. With respect to social issues, the BAU scenario is also the least preferred option with the highest risks related to security and diversity of supply, health and safety and climate change. The most sustainable options are scenarios A-3 and Green, with social barriers related to public acceptability, reliability of supply and availability of energy resource. Most critical aspects for scenario C-3 are health and safety risks, and intergenerational issues related to nuclear power. Therefore, the Mexican Government should aim to strengthen the current low carbon energy policies as well as put measures in place to encourage reducing the electricity demand. In the case of the energy policy driver focusing on climate change mitigation or annualised costs, scenarios A-3 and C-3 are the most sustainable options.EThOS - Electronic Theses Online ServiceMexican Council of Science and Technology (CONACyT)Mexican Ministry of Education (SEP)GBUnited Kingdo

Towards sustainable production and consumption: A novel DEcision-Support Framework IntegRating Economic, Environmental and Social Sustainability (DESIRES)

AbstractThe idea of sustainable production and consumption is becoming a widely-accepted societal goal worldwide. However, its implementation is slow and the world continues to speed down an unsustainable path. One of the difficulties is the sheer complexity of production and consumption systems that would need to be re-engineered in a more sustainable way as well as the number of sustainability constraints that have to be considered and satisfied simultaneously. This paper argues that bringing about sustainable production and consumption requires a systems approach underpinned by life cycle thinking as well as an integration of economic, environmental and social aspects. In an attempt to aid this process, a novel decision-support framework DESIRES has been developed comprising a suite of tools, including scenario analysis, life cycle costing, life cycle assessment, social sustainability assessment, system optimisation and multi-attribute decision analysis. An application of the framework is illustrated by a case study related to energy