What is the global potential for renewable energy?

World energy demand is projected to rise to 1000 EJ (EJ = 10¹⁸ J) or more by 2050 if economic growth continues its course of recent decades. Both reserve depletion and greenhouse gas emissions will necessitate a major shift from fossil fuels as the dominant energy source. Since nuclear power is now unlikely to increase its present modest share, renewable energy (RE) will have to provide for most energy in the future. This paper addresses the questions of what energy levels RE can eventually provide, and in what time frame. We find that when the energy costs of energy are considered, it is unlikely that RE can provide anywhere near a 1000 EJ by 2050. We further show that the overall technical potential for RE will fall if climate change continues. We conclude that the global shift to RE will have to be accompanied by large reductions in overall energy use for environmental sustainability.     

What changes,if any,would increased levels of low-carbon decentralised energy have on the built environment?

Low-carbon decentralised energy technologies (DETs) have become increasingly popular in recent UK energy policy debates. Many of the technologies involved are well established, but it is only with their increased technical maturity and the imperatives of climate change, energy security and fuel poverty that DETs have been realistically suggested as an integral part of our future built environment. This review will consider the possible physical and behavioural impacts of increased levels of low-carbon decentralised energy, presenting both recent research in this field and an analysis of policy trends and future scenarios.     

Do energy efficiency measures really reduce household energy consumption? A difference-in-difference analysis

This study investigates the impact of energy efficiency measures installed through the Carbon Emission Reduction Target (CERT) and the Community Energy Saving Programme (CESP) on domestic gas and total energy consumptions. The recently released National Energy Efficiency Data-Framework (NEED) database is used to examine the changes in domestic gas and total energy consumptions for the dwellings in the sample relative to the changes in gas and total energy consumptions for a comparable control group in the year after installation. The results obtained from this difference-in-difference analysis confirm that observed energy consumption decreases significantly in dwellings following upgrades such as cavity wall insulation, loft insulation and a new efficient boiler. The single most effective energy efficiency measure when installed alone is found to be cavity wall insulation, reducing annual gas consumption by 10.5 % and annual total energy consumption by 8.0 % in the year following installation. Comparing bundles of different energy efficiency measures, we find that dwellings retrofitted with both cavity wall insulation and a new efficient boiler experience the largest reductions in annual gas and total energy consumptions of 13.3 and 13.5 %, respectively. This is followed by a mean annual reduction of 11.9 and 10.5 % in gas and total energy consumptions for dwellings with all three energy efficiency measures installed in the same year. Contrary to expectations, installing cavity wall insulation on its own is found to be more effective in reducing measured energy consumption than combining loft insulation and a new efficient boiler.     

Community renewable energy: What should it mean?

Community is a much used word that is readily attached to projects, initiatives and policies as part of the discursive politics of modern governance. In this viewpoint, we consider the way in which community has become attached to renewable energy projects in the UK, both in grassroot action and in mainstream energy policy. We ask what those involved have seen as distinctive about community renewable energy projects that makes them different from other renewable energy installations. We identify a diversity of understandings and interpretations that revolve around questions of both process (who the project is by) and outcome (who the project is for). We evaluate the implications of this diversity, identifying the importance of the process of project development for realising the catalytic and learning effects of meaningful and substantial local involvement.     

A hydrogen standard for future energy accounting?

Present methods of energy accounting include both primary energy and final energy consumption. Both these methods have inconsistencies, although today their impact is minor. Some level of inconsistency and approximation in energy accounting is unavoidable when energy inputs come from such heterogeneous sources. We argue that in the decades to come, renewable energy will probably come to dominate the energy supply system, with most from intermittent energy sources, particularly wind and solar. In such an energy system, existing measures will become increasingly irrelevant for tracking energy use over time, for assessing a renewable energy source’s technical potential, and in determining future energy infrastructure needs. Further, conversion of most primary electricity to a storable energy form will be needed, with some then perhaps converted back to electricity as needed. We propose that in this case energy production and demand, and technical potential for renewable energy sources, will be more accurately measured by use of a new energy accounting framework, based on the energy content of hydrogen.     

What are the key drivers of MAC curves? A partial-equilibrium modelling approach for the UK

Marginal abatement cost (MAC) curves are widely used for the assessment of costs related to CO₂ emissions reduction in environmental economics, as well as domestic and international climate policy. Several meta-analyses and model comparisons have previously been performed that aim to identify the causes for the wide range of MAC curves. Most of these concentrate on general equilibrium models with a focus on aspects such as specific model type and technology learning, while other important aspects remain almost unconsidered, including the availability of abatement technologies and level of discount rates. This paper addresses the influence of several key parameters on MAC curves for the United Kingdom and the year 2030. A technology-rich energy system model, UK MARKAL, is used to derive the MAC curves. The results of this study show that MAC curves are robust even to extreme fossil fuel price changes, while uncertainty around the choice of the discount rate, the availability of key abatement technologies and the demand level were singled out as the most important influencing factors. By using a different model type and studying a wider range of influencing factors, this paper contributes to the debate on the sensitivity of MAC curves.     

National energy policies: Obstructing the reduction of global CO2 emissions? An analysis of Swedish energy policies for the district heating sector

The effect of national energy policies on a local Swedish district heating (DH) system has been studied, regarding the profitability of new investments and the potential for climate change mitigation. The DH system has been optimised regarding three investments: biomass-fuelled CHP (bio CHP), natural gas-fuelled combined cycle CHP (NGCC CHP) and biomass-fuelled heat-only boiler (bio HOB) in two scenarios (with or without national taxes and policy instruments). In both scenarios EU’s tradable CO₂ emission permits are included. Results from the study show that when national policies are included, the most cost-effective investment option is the bio CHP technology. However, when national taxes and policy instruments are excluded, the DH system containing the NGCC CHP plant has 30% lower system cost than the bio CHP system. Regardless of the scenario and when coal condensing is considered as marginal electricity production, the NGCC CHP has the largest global CO₂ reduction potential, about 300 ktonne CO₂. However, the CO₂ reduction potential is highly dependent on the marginal electricity production. Demonstrated here is that national policies such as tradable green certificates can, when applied to DH systems, contribute to investments that will not fully utilise the DH systems’ potential for global CO₂ emissions reductions.     

Cost analysis of wind-electrolyzer-fuel cell system for energy demand in Pınarbaşı-Kayseri

In this study, the hydrogen production potential and costs by using wind/electrolysis system in P?narba??-Kayseri were considered. In order to evaluate costs and quantities of produced hydrogen, for three different hub heights (50 m, 80 m and 100 m) and two different electrolyzer cases, such as one electrolyzer with rated power of 120 kW (Case-I) and three electrolyzers with rated power of 40 kW (Case-II) were investigated. Levelised cost of electricity method was used in order to determine the cost analysis of wind energy and hydrogen production. The results of calculations brought out that the electricity costs of the wind turbines and hydrogen production costs of the electrolyzers are decreased with the increase of turbine hub height. The maximum hydrogen production quantity was obtained 14192 kgH₂/year and minimum hydrogen cost was obtained 8.5 $/kgH₂ at 100 m hub height in the Case-II.     

Energy and behavioral impacts of integrative retrofits for residential buildings: What is at stake for building energy policy reforms in northern China?

Based upon the results from extensive building monitoring and surveys on occupant’s behaviors in a representative nine-story apartment building in northern China, building energy simulations were performed to evaluate the impacts of integrative retrofits implemented. Integrative retrofits required by the newer building energy standard produced significant heating-energy savings (i.e., 53%) when compared with baseline buildings commonly built in early 1980s. Taking into account district-heating-system upgrades as part of integrative retrofit measures, a representative apartment building was 66% more efficient than the baseline building. Contrary to expectation, little behavioral change was found in response to the provisions of monetary incentive, billing-method reform, or metering of heating energy use in individual apartment units. Yet this paper identified sizable energy savings potential if occupants’ behavioral changes were to actually happen. This indicates that provisions of financial incentives or individual metering were insufficient for triggering substantial behavioral changes leading toward more energy savings in the current buildings. It is recommended that innovative energy policies, technology upgrades, and education would be needed to promote behavioral changes toward additional energy savings. Finally, measures and strategies to further enhance thermal integrity criteria (e.g., insulations of roof and balcony) are recommended in China’s future building energy policy reforms.     

What lessons have been learned in reforming the Renewables Obligation? An analysis of internal and external failures in UK renewable energy policy

Despite operating a delivery programme for RES-E since 1990, UK targets and policy goals have not been achieved. In response, the Government reformed the RO. This article re-examines UK renewable energy policy by analysing the internal and external failures of the various mechanisms to determine if Government has learnt from previous experience in reforming the RO. Government did not learn from their own actions during the NFFO/RO transition, evidenced by high-levels of similarity in internal/external failures. The reformed-RO is expected to significantly increase deployment, has provided a ‘renewables package’ by comprehensively addressing both internal/external failures but major internal failures (price/financial risk) still remain, resulting in contiguous failures over two decades and two mechanism changes (NFFO, RO, RO/reformed-RO). Success will again be heavily dependent on a select few technologies and new/untested measures to combat external failures. Mechanism-extension to 2037 is probably the single most important factor underlying potential deployment increases. However, introducing a FIT-like system via the sheer number of ‘bolt-on’ reforms to counter policy failures indicates loss of direction and clarity. Overall, although Government appears to have learnt some of its lessons from the past two-decades, significant doubt remains whether renewable energy policy objectives will be met via the latest mechanism change.     

Richer and healthier,but not Greener? Choices concerning household energy use in India

India is among the world lowest per capita greenhouse gas (GHG) emitters, but rapid increases are expected. At the same time, World Health Organization (WHO) estimates show that 424,000 die prematurely in Indian households each year from air pollution exposure due to solid fuel use. We analyze GHG emissions and health through three policy scenarios for household energy, using projections for population, income and urbanization. In policy scenarios called Business as Usual (BAU), Improved Health, and Green Future, projected per capita household GHG emissions in 2026 increase by 169%, 164% and 139%, respectively, compared to 2001, whereas household mortality rates decrease by 45%, 67% and 45%, respectively. Due to income growth and urbanization, an increase in GHG emissions is likely inevitable, but can be slowed. For health, in contrast, improvements are expected and can be expanded.     

Saving money vs investing money: Do energy ratings influence consumer demand for energy efficient goods?

The article analyses economic barriers leading to the energy efficiency gap in the market for energy-using products by observing several million transactions in the UK over two years. The empirical exercise estimates AIDS models for refrigerators, washing machines, TVs, and light bulbs. Results indicate that market barriers are crucial in the demand for energy efficient options, and consumer response to changes in appliance prices, total expenditures, and energy prices depends on the possibility of behavioural adjustments in consumption. In contrast with the induced innovation hypothesis, current electricity prices can fail to induce innovation because of their short-term impact on disposable income, while consumers invest in energy efficiency when expecting electricity prices to rise in the future.     

Renewable energy strategies for rural Africa: is a PV-led renewable energy strategy the right approach for providing modern energy to the rural poor of sub-Saharan Africa?

Rural areas continue to be home to majority of the population in Africa. The importance of providing modern energy to rural areas cannot, therefore, be overemphasised. Despite numerous efforts by Governments and donors in the region to promote solar photovoltaics (PVs) for rural electrification (almost every country in the region has had a rural electrification PV project), access to modern energy in rural Africa continues to be woefully low. In addition to being unaffordable to the rural masses, solar PV has the limitation that it can only be used for lighting and powering low-voltage appliances. This article reviews emerging trends in the rural energy sector of sub-Saharan Africa, and discusses the limitations of over-reliance on solar PV. It suggests possible options that could have greater impact on rural clean energy development. For the majority of rural households in the region, biomass fuels will continue to be the dominant fuel of choice. Efficient technologies for the use of biomass would, therefore, ensure that scarce biomass resources are effectively utilised, and reduce the negative impacts of biomass use on women and children's health. Solar thermal, windpumps, micro-/pico-hydropower and cleaner fuels such as kerosene and LPG, have not received adequate attention from policy makers. These energy options could significantly improve the performance of rural small- and micro-enterprises. This article argues that rural energy policies that emphasise a broader range of renewables and target income-generating activities are likely to yield greater benefits to the rural poor than the current policies that rely on the solar PV option.     

A new method of energy degradation on-line analysis for coal-fired unit—expansion line approximating method

An energy degradation analysis process of unit and thermal system for coal-fired power plant under condition at discretion is discussed when load has been changed greatly in this paper. A new method of expansion line approximating method, which can rationally calculate the quantity of every component of energy degradation and identify the places where energy degradations arise, is put forward. In addition, the quality of every component of energy degradation is also discussed.     

Is there a role for biofuels in promoting energy self sufficiency and security? A CGE analysis of biofuel policy in Thailand

Given the rising price of crude oil, some developing countries including Thailand are looking towards developing their domestic renewable energy resources, in particular biofuels. However, there are concerns about the possible adverse effects such a policy strategy would have on key variables such as sectoral output, land allocation and the effects of prices, particularly food prices. This study develops a computable general equilibrium (CGE) model of the Thailand economy that features enhancements of the energy sector and uses it to analyze the government’s recent renewable energy development plan. This plan aims to increase domestic energy use from renewable sources to replace fossil fuel imports. The study simulated specific policies contained in the plan. Among other things, we found that promoting biofuel use causes a rapid increase in the price of biofuel and biofuel feedstock in the short-run, whereas these prices only increase slightly in the long-run due to more elastic supplies. The prices of food and other products marginally increase, implying that food security is not undermined by the policy. On the basis of the findings, the study recommends a review of some of the targets because they were found to be rather high, and a phasing in of others.     

Feedback on household electricity consumption: a tool for saving energy?

Improved feedback on electricity consumption may provide a tool for customers to better control their consumption and ultimately save energy. This paper asks which kind of feedback is most successful. For this purpose, a psychological model is presented that illustrates how and why feedback works. Relevant features of feedback are identified that may determine its effectiveness: frequency, duration, content, breakdown, medium and way of presentation, comparisons, and combination with other instruments. The paper continues with an analysis of international experience in order to find empirical evidence for which kinds of feedback work best. In spite of considerable data restraints and research gaps, there is some indication that the most successful feedback combines the following features: it is given frequently and over a long time, provides an appliance-specific breakdown, is presented in a clear and appealing way, and uses computerized and interactive tools.

Fuelwood: The “other” renewable energy source for Africa?

In recent years, increasing concerns over rising oil prices, supply shortfalls and the environmental impacts of fossil fuel use have fed growing interest in renewable energy sources for Sub-Saharan Africa. Although traditional biofuels already enjoy widespread popularity, their use has often been actively discouraged due to the lingering influence of “fuelwood crisis” era narratives. In particular, urban fuelwood consumption is frequently portrayed as a cause of environmental degradation leading to energy insecurity among low-income households, especially where the resource is commercialized. Such views have had significant influence among policy makers, often resulting in repressive forestry legislation. In contrast, however, a number of researchers have demonstrated that wood energy dependence is often not a significant cause of deforestation and can provide important livelihood opportunities. This article reassesses urban fuelwood sourcing and its impacts using a recent case study conducted by the authors in Maun, Botswana and results previously reported in the literature. Findings indicate that although harvesting is unregulated, its impacts are significantly mitigated by collectors' strong preferences for source sites with abundant dead wood, low competition and recognized access rights. As well, fuelwood vending is found to provide critical support to rural incomes and a key source of low-cost urban energy. As such, the benefits of fuelwood use and avoidance of negative effects will most effectively be achieved by decentralised management approaches that build on local institutions and understandings of the resource.     

What can we learn from high-frequency appliance-level energy metering? Results from a field experiment

This study uses high-frequency appliance-level electricity consumption data for 124 apartments over 24 months to provide a better understanding of appliance-level electricity consumption behavior. We conduct our analysis in a standardized set of apartments with similar appliances, which allows us to identify behavioral differences in electricity use. The Results show that households' estimations of appliance-level consumption are inaccurate and that they overestimate lighting use by 75% and underestimate plug-load use by 29%. We find that similar households using the same major appliances exhibit substantial variation in appliance-level electricity consumption. For example, households in the 75th percentile of HVAC usage use over four times as much electricity as a user in the 25th percentile. Additionally, we show that behavior accounts for 25–58% of this variation. Lastly, we find that replacing the existing refrigerator with a more energy-efficient model leads to overall energy savings of approximately 11%. This is equivalent to results from behavioral interventions targeting all appliances but might not be as cost effective. Our findings have important implications for behavior-based energy conservation policies.