Greenhouse gas emissions and energy balances of jatropha biodiesel as an alternative fuel in Tanzania

This paper evaluates GHG emissions and energy balances (i.e. net energy value (NEV), net renewable energy value (NREV) and net energy ratio (NER)) of jatropha biodiesel as an alternative fuel in Tanzania by using life cycle assessment (LCA) approach. The functional unit (FU) was defined as 1 tonne (t) of combusted jatropha biodiesel. The findings of the study prove wrong the notion that biofuels are carbon neutral, thus can mitigate climate change. A net GHG equivalent emission of about 848 kg t⁻¹ was observed. The processes which account significantly to GHG emissions are the end use of biodiesel (about 82%) followed by farming of jatropha for about 13%. Sensitivity analysis indicates that replacing diesel with biodiesel in irrigation of jatropha farms decreases the net GHG emissions by 7.7% while avoiding irrigation may reduce net GHG emissions by 12%. About 22.0 GJ of energy is consumed to produce 1 t of biodiesel. Biodiesel conversion found to be a major energy consuming process (about 64.7%) followed by jatropha farming for about 30.4% of total energy. The NEV is 19.2 GJ t⁻¹, indicating significant energy gain of jatropha biodiesel. The NREV is 23.1 GJ t⁻¹ while NER is 2.3; the two values indicate that large amount of fossil energy is used to produce biodiesel. The results of the study are meant to inform stakeholders and policy makers in the bioenergy sector.     

Interactions and implications of renewable and climate change policy on UK energy scenarios

As a response to the twin challenges of climate change mitigation and energy security, the UK government has set a groundbreaking target of reducing the UK’s economy-wide carbon emissions by 80% from 1990 levels by 2050. A second key UK energy policy is to increase the share of final energy consumption from renewables sources to 15% by 2020, as part of the wider EU Renewable Directive. The UK’s principle mechanisms to meet this renewable target are the Renewable Obligation (RO) in the electricity sector, the Renewable Transport Fuel Obligation (RTFO), and most recently the Renewable Heat Programme (RHP) for buildings. This study quantifies a range of policies, energy pathways, and sectoral trade-offs when combining mid- and long-term UK renewables and CO₂ reduction policies. Stringent renewable policies are the binding constraints through 2020. Furthermore, the interactions between RO, RTFO, and RHP policies drive trade-offs between low carbon electricity, bio-fuels, high efficiency natural gas, and demand reductions as well as resulting 2020 welfare costs. In the longer term, CO₂ reduction constraints drive the costs and characteristics of the UK energy system through 2050.     

Renewable energy and policy options in an integrated ASEAN electricity market: Quantitative assessments and policy implications

Energy market integration (EMI) in the ASEAN region is a promising solution to relieve the current immobilization of its renewable energy resources and would serve the fast increasing demand for electricity in the region. EMI could be further extended with coordinated policies in carbon pricing, renewable energy portfolio standards (RPS), and feed-in-tariffs (FIT) in the ASEAN countries. Using a linear dynamic programming model, this study quantitatively assesses the impacts of EMI and the above-mentioned policies on the development of renewable energy in the power generation sector of the region, and the carbon emissions reduction achievable with these policies. According to our results, EMI is expected to significantly promote the adoption of renewable energy. Along with EMI, FIT appears to be more cost-effective than RPS and is recommended for the ASEAN region, albeit political barriers for policy coordination among the countries might be a practical concern. In addition, an RPS of 30% electricity from renewable sources by 2030, which is considered politically a “low-hanging fruit”, would achieve moderate improvements in carbon emissions reductions and renewable energy development, while incurring negligible increases in the total cost of electricity.     

Characterization of fine root system and potential contribution to soil organic carbon of six perennial bioenergy crops

Perennial bioenergy crops provide biomass for renewable energy production, but also sequester atmospheric carbon (C) in the soil. Roots represent one of the most important soil C inputs-root length density (RLD, cm cm⁻³), root diameter and fine root biomass (FRB, Mg ha⁻¹) in the top 1 m of soil were characterized for three woody (poplar, black locust, willow) and three herbaceous (giant reed, miscanthus, switchgrass) perennial crops in the same location. The vertical distribution of FRB and RLD was described by fitting the “beta” (β) model to the experimental data. The herbaceous species had higher β values for FRB and RLD than woody crops, suggesting that the former explore the deeper soil layers with a greater proportion of roots. In particular, 3.7 Mg ha⁻¹, or 43% of the whole root mass, was found below the ploughing soil layer (0.3 m) for the herbaceous species, while only 1.2 Mg ha⁻¹, or 26% of the whole root mass, was allocated by woody crops to the same soil layer. In all the species, the majority of the sampled roots (99.1%) had a diameter lower than 2 mm, and in the first 10 cm of the soil the woody species tended to produce roots with a smaller diameter than those of the herbaceous species. Overall, the herbaceous crops have a higher potential to contribute to C storage in the deep soil layers, while the woody species, have a greater potential to affect soil organic carbon in the top soil layer.     

Investment in wind power and pumped storage in a real options model

Promoting renewable energy has been a key ingredient in energy policy seeking to de-carbonize the energy mix and will continue to do so in the future given the European Union's high ambitions to further curb carbon emissions. A wide range of instruments has been suggested and implemented in various countries of the EU. A prominent policy promoting investment in renewable technologies is the use of feed-in tariffs, which has worked well at large scale in, e.g. Germany, but which has only been implemented in a very limited way in countries such as the UK.Being subject to environmental uncertainties, however, renewables cannot be seen in isolation: while renewables-based technologies such as wind and solar energy, for example, suffer from uncertain loads depending on environmental conditions, hydropower allows for the storage of water for release at peak prices, which can be treated as a premium (partially) offsetting higher upfront investment costs. In addition, electricity prices will respond to changes in electric capacity in the market, which is often neglected in standard investment models of the electricity sector.This paper contributes to the existing literature in two ways: it provides a review of a renewables-based technology in a specific policy context and provides additional insight by employing a real options approach to investigate the specific characteristics of renewables and their associated uncertainties in a stylized setting taking explicitly into account market effects of investment decisions. The prices of the model are determined endogenously by the supply of electricity in the market and by exogenous electricity price uncertainty. The inclusion of market effects allows us to capture the full impact of public incentives for companies to invest into wind power and hydro pumped storage installations.     

Opportunities for low carbon sustainability in large commercial buildings in China

China's building sector consumes one quarter of total energy consumption in the country and plays an important role in long-term ability of the country to achieve sustainable development. This paper discusses a comprehensive approach to achieving low carbon sustainability in large commercial buildings in China incorporating both energy and carbon-reduction strategies. The approach concentrates primarily on three complementary aspects: (a) the introduction of an effective energy management system; (b) the incorporation of relevant advanced energy saving technologies and measures and (c) the promotion of awareness among occupants to make changes in their behaviour towards a more environmental-friendly behaviour. However, reference is also made to the role that renewable energy and offsetting may have in the effective management and environmental performance of buildings.Nine examples of large commercial buildings in Beijing and Shanghai were studied and the average electricity consumption of around 153 kWh/m² per annum is about 5 times higher than average electricity use in residential buildings. At the same time the associated green house gas (GHG) emissions are around 158 kg/m² per annum.     

Bioenergy technologies for carbon abatement

In this paper, bioenergy technologies (BETs) are presented as potential carbon abatement opportunities substituting fossil fuel or traditional (less efficient) biomass energy systems. Cost of energy (produced or saved) of BETs is compared with fossil fuel and traditional biomass energy systems to estimate the incremental cost (IC). The IC of carbon abatement for each of the selected BETs (in $ kWh⁻¹ or $ GJ⁻¹) is estimated using the carbon emission (tC kWh⁻¹ or tC GJ⁻¹) reduction obtained by substituting fossil fuel and traditional biomass alternatives. The abatement costs are estimated and compared for ten combinations of BETs (with seven technology alternatives) substituting conventional technologies. The analysis indicates that out of the ten project cases six have negative ICs in the range of −37 to −688 $ tC⁻¹ and four have positive ICs in the range of 52–162 $ tC⁻¹ mitigation. The negative ICs indicate that the suggested alternatives are cheaper than the original technologies. Thus, results indicate that the chosen BETs are cost-effective mitigation opportunities and are currently aggressive candidates under Clean Development Mechanism.     

Wind farms on undegraded peatlands are unlikely to reduce future carbon emissions

Onshore wind energy is a key component of the renewable energies used by governments to reduce carbon emissions from electricity production, but will carbon emissions be reduced when wind farms are located on carbon-rich peatands? Wind farms are often located in uplands because most are of low agricultural value, are distant from residential areas, and are windy. Many UK uplands are peatlands, with layers of accumulated peat that represent a large stock of soil carbon. When peatlands are drained for construction there is a higher risk of net carbon loss than for mineral soils. Previous work suggests that wind farms sited on peatlands can reduce net carbon emissions if strictly managed for maximum retention of carbon. Here we show that, whereas in 2010, most sites had potential to provide net carbon savings, by 2040 most sites will not reduce carbon emissions even with careful management. This is due to projected changes in the proportion of fossil fuels used to generate electricity. The results suggest future policy should avoid constructing wind farms on undegraded peatlands unless drainage of peat is minimal and the volume excavated in foundations can be significantly reduced compared to energy output.     

The role of energy efficiency in reducing Scottish and UK CO2 emissions

In 2003, the UK government launched its long-anticipated White Paper on energy, the centrepieces of which were ambitious targets for the production of electricity from renewable technologies and the long-term aspiration of a 60% reduction in UK greenhouse gas emissions by 2050. In the White Paper it was recognised that such a dramatic reduction in emissions will require significant changes in the way in which energy is produced and used. However there has been a general failure to recognise the fact that in order to meet emissions targets, the UK will have to significantly reduce its energy consumption; this is not helped by the general misconception in the UK that reductions in CO₂ emissions will occur simply by increasing the production of electricity from renewable sources.

Specifically, this paper highlights the current trends in renewables deployment and energy demand, with a specific focus on Scotland, where the authorities have set more ambitious renewables targets than the rest of the UK. As will be demonstrated in this paper, without energy demand reduction, the deployment of renewables alone will not be sufficient to curtail growth in UK CO₂ emissions. This is illustrated using a case study of the Scottish housing sector; whilst this case study is necessarily local in scope, the results have global relevance. The paper will also address the magnitude of energy savings required to bring about a reduction in emissions and assesses the status of the policies and technologies that could help bring such reductions about.     

Economics of herbaceous bioenergy crops for electricity generation: Implications for greenhouse gas mitigation

This paper examines the optimal land allocation for two perennial crops, switchgrass and miscanthus that can be co-fired with coal for electricity generation. Detailed spatial data at county level is used to determine the costs of producing and transporting biomass to power plants in Illinois over a 15-year period. A supply curve for bioenergy is generated at various levels of bioenergy subsidies and the implications of production for farm income and greenhouse gas (GHG) emissions are analyzed. GHG emissions are estimated using lifecycle analysis and include the soil carbon sequestered by perennial grasses and the carbon emissions displaced by these grasses due to both conversion of land from row crops and co-firing the grasses with coal. We find that the conversion of less than 2% of the cropland to bioenergy crops could produce 5.5% of the electricity generated by coal-fired power plants in Illinois and reduce carbon emissions by 11% over the 15-year period. However, the cost of energy from biomass in Illinois is more than twice as high as that of coal. Costly government subsidies for bioenergy or mandates in the form of Renewable Portfolio Standards would be needed to induce the production and use of bioenergy for electricity generation. Alternatively, a modest price for GHG emissions under a cap-and-trade policy could make bioenergy competitive with coal without imposing a fiscal burden on the government.     

Implications of CO2 reduction policies for a high carbon emitting economy

This paper uses a dynamic computable general equilibrium model to compare the macroeconomic and sectoral impacts of three environmental policies in Australia — an emissions trading scheme (ETS), an ETS combined with technological innovation in the renewable energy sector and a fuel tax as an alternative to the ETS. Overall, the impacts of the ETS were not significantly adverse. Although the fuel tax had similar impacts to the ETS on key macro-variables such as real GDP, employment, household consumption, exports and imports, it was however not effective compared to the latter in reducing emissions. Neither policy led to inflation growth of more than 0.8% for any coal mining and non-mining Australian state. At the sectoral level, the GDP growth of energy-intensive industries such as coal, iron ore, steel and coal-powered electricity generators is adversely affected while electricity generators who use gas and renewable energy sources and the forestry sector gain. It was also found that a 10% technological change in the renewable energy sector over a decade did not significantly improve the outcome when coupled with the ETS. Thus the Australian government's industry assistance to invest in low pollution technologies needs to be more aggressive to meet current and future international emission abatement targets.     

Policies to reduce energy use and carbon emissions in the UK

The UK differs from may other industrialized nations in that its carbon dioxide (CO₂) emissions from energy use have declined in recent years despite relatively rapid economic growth. In all sectors but transport, substantial reductions have already occurred in the level of carbon emissions per unit of GDP output. At the same time, a number of official and unofficial studies have pointed out that the UK has one of the largest remaining potentials amongst comparable industrialized countries for achieving further CO₂ reductions through the implementation of cost-effective energy efficiency and fuel switching measures. This paper discusses past and present patterns of energy use and carbons emissions in the UK. The analysis then examines historical trends in UK energy policy and presents policy options for further reducing the UK's energy-use and carbon emissions in the future.     

Demand reduction in the UK—with a focus on the non-domestic sector

A demand reduction strategy is considered in the context of the UK and in the light of the UK Government's 2006 Energy Review. This paper discusses how a mechanism—a Demand Reduction Obligation (DRO)—can be established to achieve radical energy demand reduction targets in electricity and gas use in the industrial, commercial and public administration sectors. A DRO would require energy suppliers to invest in energy-saving measures so as to reduce energy demand in these sectors. The investment for this activity would be funded by energy suppliers who would increase prices in order to cover the cost of achieving the carbon reductions. Public opinion surveys suggest that a large proportion of the public would prefer to support demand reduction measures compared to other energy options. It may be practical to deliver carbon emission reductions equivalent to around 30% of emissions from the UK electricity sector over a 15-year period through a broad-based demand reduction strategy. Demand reduction is considered in the context of an assessment of costs and resources available from other low carbon options including renewable energy and nuclear power.     

Evaluating carbon dioxide emissions in international trade of China

China is the world's largest emitter of carbon dioxide (CO₂). As exports account for about one-third of China's GDP, the CO₂ emissions are related to not only China's own consumption but also external demand. Using the input–output analysis (IOA), we analyze the embodied CO₂ emissions of China's import and export. Our results show that about 3357 million tons CO₂ emissions were embodied in the exports and the emissions avoided by imports (EAI) were 2333 million tons in 2005. The average contribution to embodied emission factors by electricity generation was over 35%. And that by cement production was about 20%. It implies that the production-based emissions of China are more than the consumption-based emissions, which is evidence that carbon leakage occurs under the current climate policies and international trade rules. In addition to the call for a new global framework to allocate emission responsibilities, China should make great efforts to improve its energy efficiency, carry out electricity pricing reforms and increase renewable energy. In particular, to use advanced technology in cement production will be helpful to China's CO₂ abatement.     

Life cycle assessment of the electrolytic production and utilization of low carbon hydrogen vehicle fuel

Environmental burdens associated with small scale (40 L hydrogen per minute) production of hydrogen fuel using electrolysis powered by electricity generated from stand-alone wind turbines (30 kW), stand-alone photovoltaic panels (3 kW peak) and UK grid electricity (current and future) has been undertaken. Utilization of fuel within a proton exchange membrane fuel cell passenger vehicle was included and compared to the operation of a petrol vehicle, a fuel cell vehicle fuelled with non-renewable hydrogen, and an electric (battery only) vehicle. The production of renewable hydrogen from wind energy incurs increased climate change burdens compared with extraction and processing of fossil petrol (0.09 mPt compared with 0.07 mPt). However, lower burdens for fossil fuel (1.85 mPt) and climate change (0.26 mPt) are realised by the renewable hydrogen options compared with petrol (4.44 mPt and 0.44 mPt, respectively) following utilization of the fuel due to lower emissions at end use. Utilizing a combination of renewable hydrogen fuelled vehicles and grid powered electric vehicles was considered to be a viable option for meeting UK policy ambitions.     

The forest products industry at an energy/climate crossroads

Transformational energy and climate policies are being debated worldwide that could have significant impact upon the future of the forest products industry. Because woody biomass can produce alternative transportation fuels, low-carbon electricity, and numerous other “green” products in addition to traditional paper and lumber commodities, the future use of forest resources is highly uncertain. Using the National Energy Modeling System (NEMS), this paper assesses the future of the forest products industry under three possible U.S. policy scenarios: (1) a national renewable electricity standard, (2) a national policy of carbon constraints, and (3) incentives for industrial energy efficiency. In addition, we discuss how these policy scenarios might interface with the recently strengthened U.S. renewable fuels standards. The principal focus is on how forest products including residues might be utilized under different policy scenarios, and what such market shifts might mean for electricity and biomass prices, as well as energy consumption and carbon emissions. The results underscore the value of incentivizing energy efficiency in a portfolio of energy and climate policies in order to moderate electricity and biomass price escalation while strengthening energy security and reducing CO₂ emissions.     

The case for a new energy research,development and promotion policy for the UK

This paper is a critical assessment of the current balance of efforts towards energy research and development (R&D) and the promotion of low-carbon electricity technologies in the UK. We review the UK's main technological options and their estimated cost ranges in the medium term. We contrast the energy R&D spending with the current and expected future cost of renewable promotion policies and point out the high cost of carbon saving through existing renewable promotion arrangements. We also note that liberalisation of the electricity sector has had significant implications for the landscape of energy R&D in the UK. We argue that there is a need for reappraisal of the soundness and balance of the energy R&D and renewable capacity deployment efforts towards new energy technologies. We suggest that the cost-effectiveness of UK deployment policies needs to be more closely analysed as associated costs are non-trivial and expected to rise. We also make a case for considering increasing the current low level of energy R&D expenditure. Much of energy R&D is a public good and we should consider whether the current organisation of R&D effort is fit for purpose. We argue that it is important to build and maintain the research capability in the UK in order to absorb spillovers of technological progress elsewhere in the world. Against this background, the recent signs that an energy R&D renaissance could be underway are therefore positive and welcome.     

Green electricity production with living plants and bacteria in a fuel cell

The world needs sustainable, efficient, and renewable energy production. We present the plant microbial fuel cell (plant-MFC), a concept that exploits a bioenergy source in situ. In the plant-MFC, plants and bacteria were present to convert solar energy into green electricity. The principal idea is that plants produce rhizodeposits, mostly in the form of carbohydrates, and the bacteria convert these rhizodeposits into electrical energy via the fuel cell. Here, we demonstrated the proof of principle using Reed mannagrass. We achieved a maximal electrical power production of 67 mW m⁻² anode surface. This system was characterized by: (1) nondestructive, in situ harvesting of bioenergy; (2) potential implementation in wetlands and poor soils without competition to food or conventional bioenergy production, which makes it an additional bioenergy supply; (3) an estimated potential electricity production of 21 GJ ha⁻¹ year⁻¹ (5800 kWh ha⁻¹ year⁻¹) in Europe; and (4) carbon neutral and combustion emission-free operation. Copyright © 2008 John Wiley & Sons, Ltd.     

The production of hydrogen fuel from renewable sources and its role in grid operations

Understanding the scale and nature of hydrogen's potential role in the development of low carbon energy systems requires an examination of the operation of the whole energy system, including heat, power, industrial and transport sectors, on an hour-by-hour basis. The Future Energy Scenario Assessment (FESA) software model used for this study is unique in providing a holistic, high resolution, functional analysis, which incorporates variations in supply resulting from weather-dependent renewable energy generators. The outputs of this model, arising from any given user-definable scenario, are year round supply and demand profiles that can be used to assess the market size and operational regime of energy technologies. FESA was used in this case to assess what - if anything - might be the role for hydrogen in a low carbon economy future for the UK.In this study, three UK energy supply pathways were considered, all of which reduce greenhouse gas emissions by 80% by 2050, and substantially reduce reliance on oil and gas while maintaining a stable electricity grid and meeting the energy needs of a modern economy. All use more nuclear power and renewable energy of all kinds than today's system. The first of these scenarios relies on substantial amounts of ‘clean coal’ in combination with intermittent renewable energy sources by year the 2050. The second uses twice as much intermittent renewable energy as the first and virtually no coal. The third uses 2.5 times as much nuclear power as the first and virtually no coal.All scenarios clearly indicate that the use of hydrogen in the transport sector is important in reducing distributed carbon emissions that cannot easily be mitigated by Carbon Capture and Storage (CCS). In the first scenario, this hydrogen derives mainly from steam reformation of fossil fuels (principally coal), whereas in the second and third scenarios, hydrogen is made mainly by electrolysis using variable surpluses of low-carbon electricity. Hydrogen thereby fulfils a double facetted role of Demand Side Management (DSM) for the electricity grid and the provision of a ‘clean’ fuel, predominantly for the transport sector. When each of the scenarios was examined without the use of hydrogen as a transport fuel, substantially larger amounts of primary energy were required in the form of imported coal.The FESA model also indicates that the challenge of grid balancing is not a valid reason for limiting the amount of intermittent renewable energy generated. Engineering limitations, economic viability, local environmental considerations and conflicting uses of land and sea may limit the amount of renewable energy available, but there is no practical limit to the conversion of this energy into whatever is required, be it electricity, heat, motive power or chemical feedstocks.     

Adoption of energy efficient technologies and carbon abatement: the electricity generating sector in India

A behavioral micro-economic framework was developed to analyze the impact of alternative mixes of policy reforms that eliminate existing regulatory distortions and a carbon emissions-tax on incentives to adopt energy efficient technologies and their implications for carbon emissions and output. An empirical application of this framework to the electricity-generating sector in India demonstrates that elimination of existing domestic and trade policy distortions has the potential to reduce carbon emissions even in the absence of an emissions-tax, by inducing the adoption of energy efficient technologies. In the presence of these policy reforms, an emissions-tax achieves a given level of abatement with higher output levels than in the absence of these reforms. This analysis indicates the potential for achieving a complementarity between the goals of reducing carbon emissions and increasing electricity generation by identifying the regulatory distortions that are hindering adoption of energy efficient technologies and tailoring policy reforms to specific distortions.