Technical and economic performance of residential solar water heating in the United States

This paper examines the regional, technical, and economic performance of residential rooftop solar water heating (SWH) technology in the U.S. It focuses on the application of SWH to consumers in the U.S. currently using electricity for water heating, which currently uses over 120 billion kWh per year. The variation in electrical energy savings due to water heating use, inlet water temperature and solar resource is estimated and applied to determine the regional “break-even” cost of SWH where the life-cycle cost of SWH is equal the life-cycle energy savings. For a typical residential consumer, a SWH system will reduce water heating energy demand by 50–85%, or a savings of 1600–2600 kWh per year. For the largest 1000 electric utilities serving residential customers in the United States as of 2008, this corresponds to an annual electric bill savings range of about $100 to over $300, reflecting the large range in residential electricity prices. This range in electricity prices, along with a variety of incentives programs corresponds to a break-even cost of SWH in the United States varying by more than a factor of five (from less than $2250/system to over $10,000/system excluding Hawaii and Alaska), despite a much smaller variation in the amount of energy saved by the systems (a factor of approximately one and a half). We also consider the relationships between collector area and technical performance, SWH price and solar fraction (percent of daily energy requirements supplied by the SWH system) and examine the key drivers behind break-even costs.     

Energy efficiency standards for refrigerators in Brazil: A methodology for impact evaluation

In Brazil energy efficiency standards for cold appliances was established in 2007. A specified single set of MEPS (minimum energy performance standards) for refrigerators, freezers and freezer refrigerators was implemented without evaluating its impacts and estimation of potential electricity savings. This paper presents a methodology for assessing the impacts of the Brazilian MEPS for cold appliances. It uses a bottom-up approach to estimate residential end-use consumption and to evaluate the energy saving potential for refrigerators. The household electricity consumption is projected by modeling appliance ownership using an econometric approach based on the recent household survey data. A cost–benefit analysis for more stringent standards is presented from the perspective of the society and electricity customers. The results showed that even considering the current market conditions (high discount rate for financing new efficient equipment) some MEPS options are advantageous for customers. The analysis also demonstrates significant cost-effective saving potential from the society perspective that could reach 21 TWh throughout the period of 2010–2030—about 25% of current residential consumption.     

Can deployment of renewable energy put downward pressure on natural gas prices?

High and volatile natural gas prices have increasingly led to calls for investments in renewable energy. One line of argument is that deployment of these resources may lead to reductions in the demand for and price of natural gas. Many recent US-based modeling studies have demonstrated that this effect could provide significant consumer savings. In this article we evaluate these studies, and benchmark their findings against economic theory, other modeling results, and a limited empirical literature. We find that many uncertainties remain regarding the absolute magnitude of this effect, and that the reduction in natural gas prices may not represent an increase in aggregate economic wealth. Nonetheless, we conclude that many of the studies of the impact of renewable energy on natural gas prices appear to have represented this effect within reason, given current knowledge. These studies specifically suggest that a 1% reduction in US natural gas demand could lead to long-term average wellhead price reductions of 0.8–2%, and that each megawatt-hour of renewable energy may benefit natural gas consumers to the tune of at least $7.5–20.     

Industrial combined heat and power (CHP) planning: Development of a methodology and application in Greece

This paper establishes a methodology for the estimation of the primary energy savings of an industrial (sub)-sector and the primary energy savings of the total energy system due to CHP. A primary energy savings indicator within a (sub)-sector and a total primary energy savings indicator are developed which are related with the actual energy use of a (sub)-sector and the way of disposal of the excess CHP energy produced. The methodology is applied in an industrial sub-sector in Greece according to the ‘power match’ and the ‘thermal match’ CHP sizing scenarios; subsequently results are presented and the developed indicators are fully explained. It was found that the primary energy savings indicator of a sub-sector is determined by the efficiencies of the relevant technologies, and the interrelation of the ‘power to heat’ ratio of the CHP technology used and the ‘power to heat’ ratio of the sub-sector examined; the total primary energy savings indicator is determined by the efficiencies of the relevant technologies and the percentage of the CHP energy exported from the sub-sector. The methodology can be utilized for optimum CHP planning.     

Effect of heat-saving measures on the CO2 savings attributable to micro-combined heat and power (μCHP) systems in UK dwellings

This paper considers the relationship between heat-saving and micro-combined heat and power (μCHP) technological interventions for reducing the carbon footprint of existing domestic dwellings within the UK housing stock. The relationship between the annual heat requirement of individual dwellings and the CO₂ savings attributable to different μCHP systems is investigated (by means of predictive modelling based on heat and power demand datasets recorded on a 1-min time base for nine dwellings). An assessment is made of the effects of various heat-saving measures upon the annual CO₂ savings predictions for candidate μCHP system implementations, when applied to ‘domestic building variants’ (as defined within the Carbon Vision TARBASE research programme). The increasing application of heat-saving interventions serves to reduce the CO₂ savings solely attributable to a μCHP system. The magnitude of this effect is a function of the μCHP system's electrical efficiency and electrical power output. For example, a 1 kW prime mover of 10% electrical efficiency is predicted to reduce annual CO₂ emissions by 72 kg CO₂ for a dwelling with an annual heat requirement of 11.9 MWh, but if the identified set of heat-saving measures is implemented first the demand falls to 5.0 MWh and the μCHP system will actually result in an emissions increase of 100 kg CO₂ p.a. By comparison, relative savings of 467 and 294 kg CO₂ p.a. are predicted if this dwelling is fitted with a 1 kW prime mover of 30% electrical efficiency. Still greater savings are predicted for higher power output systems of high efficiency, but a relatively large proportion of the generated electricity (44–75% depending on the heat and electrical demand of the dwelling) must then be exported.     

Economic and environmental impacts from the implementation of an intelligent demand side management system at the European level

This paper presents the results of an analysis on the economic and environmental impacts of the application of an intelligent demand side management system, called the Energy Consumption Management System (ECMS), in the European countries. The ECMS can be applied for the control of individual, widely distributed electric loads, using the power distribution network as the command communication channel. The system can be applied in public lighting, in the tertiary and residential sectors, as well as in the industry. A top-down analysis investigates the possible penetration levels in each application area. The long-term impacts following the application of system are evaluated using the LEAP2006 platform. The WASP IV model is also used for the optimization of the power generation expansion and the corresponding calibration of LEAP2006. Several operational strategies combining variable market penetration of the ECMS and expected energy savings are examined. Results show that, under a logical market penetration, a reduction of 1–4% in primary energy, of 1.5–5% in CO₂ emissions and a 2–8% saving in investment costs for power generation expansion is to be expected for the EU-15. The results also justify that innovative devices may be attractive to end users and also help in the implementation of global energy-saving policies.     

Refurbishment of public housing villas in the United Arab Emirates (UAE): energy and economic impact

This study aims at assessing the technical and economic benefits of refurbishing existing public housing villas in the UAE. Four representative federal public housing villas built between 1980s and 2010s were modeled and analyzed. The Integrated Environmental Solutions-Virtual Environment (IES-VE) energy modeling software was used to estimate the energy consumption and savings due to different refurbishment configurations applied to the villas. The refurbishment technical configurations were based on the UAE’s Estidama green buildings sustainability assessment system. The refurbishment configurations include upgrading three elements: the wall and roof insulation as well as replacing the glazing. The annual electricity savings results indicated that the most cost-efficient refurbishment strategy is upgrading of wall insulation (savings up to 20.8 %) followed by upgrading the roof’s insulation (savings up to 11.6 %) and lastly replacing the glazing (savings up to 3.2 %). When all three elements were refurbished simultaneously, savings up to 36.7 % were achieved (villa model 670). The savings translated to CO₂ emission reduction of 22.6 t/year. The simple and discounted payback periods for the different configurations tested ranged between 8 and 28 and 10 and 50 years, respectively.     

The role of energy efficiency spending in Maryland’s implementation of the Regional Greenhouse Gas Initiative

What are the economic consequences of increased state spending on electricity consumption efficiency? The State of Maryland faces this question in deciding how much of its CO₂ allowances auction proceeds (under the Regional Greenhouse Gas Initiative) to devote to such programs. Starting at a base of 25% of the proceeds, we consider the energy savings, emissions reductions, employment, and other impacts of increasing that percentage to 50% and 100%. A series of models – Haiku, JHU-OUTEC, and IMPLAN – are used for the analysis. We conclude that increasing the state’s expenditures on energy efficiency programs would result in a decline in electricity consumption in the state and a corresponding decline in expenditures on electricity. Program implementation would lead to net positive growth in statewide economic activity and include growth in both jobs and wages.     

中国与苏丹的石油合作

苏丹石油资源丰富,2007年石油探明储量为66×108bbl。为了开发本国的石油资源,苏丹出台了一系列鼓励投资的优惠政策,为中苏石油合作提供了机会。苏丹是中国海外寻油最早的目的地之一,经过10多年的不懈努力,中国已在苏丹逐步形成集生产、精炼、运输、销售于一体的完整的石油工业产业链。中国与苏丹在石油领域的合作堪称中国在非洲实施＂走出去＂战略的成功典范,每年为中国带来数百万吨的权益油和稳定的石油供应渠道,同时也有力地促进了苏丹的经济发展。中国企业积极投身公益事业,热情为当地民众造福,赢得了苏丹政府和人民的称赞。然而由于苏丹产业结构单一,经济发展存在不稳定性,再加上达尔富尔问题和西方的恶意诽谤,使得中苏石油合作面临着挑战。但随着中苏石油领域合作的不断深入,相信两国互惠互利、共同发展的目标一定能实现。     

The assessment of health damage caused by air pollution and its implication for policy making in Taiyuan,Shanxi, China

We establish the link between energy use, air pollution, and public health impacts in Taiyuan for 2000, and for 2010 and 2015 under alternative scenarios. We find that in year 2000 more than 2200 excess deaths may have been caused by particulate matter (PM) pollution. Using alternative methods for monetization of health impacts the total health damage amounts to 0.8–1.7 billion Yuan, which is 2.4–4.9% of the city's GDP in 2000. Compared to the business-as-usual scenario, scenarios assuming extensive fuel switch in low-and-medium-stack pollution sources and extension of the district heating system could prevent 200–1100 PM₁₀-related premature deaths in 2010 and substantially reduce population morbidity. The actual PM pollution in 2007 was lower than modeled in these two scenarios. We also find that if air quality in urban Taiyuan were to reach the Chinese National Grade II Standard in 2015, the number of premature deaths would still be around 1330 and the economic cost about 1–2% of the city's GDP in 2015. Our results imply that there are large health benefits to be gained by setting stricter standards for the future in China, and that targeting low-and-medium-stack source effectively reduces health damage.     

Assessment of China's energy-saving and emission-reduction accomplishments and opportunities during the 11th Five Year Plan

From 1980 to 2002, China experienced a 5% average annual reduction in energy consumption per unit of gross domestic product (GDP). With a dramatic reversal of this historic relationship, energy intensity increased 5% per year during 2002–2005. China's 11th Five Year Plan (FYP) set a target of reducing energy intensity by 20% by 2010. This paper assesses selected policies and programs that China has instituted to fulfill the national goal, finding that China made substantial progress and many of the energy-efficiency programs appear to be on track to meet – or in some cases exceed – their energy-saving targets. Most of the Ten Key Projects, the Top-1000 Program, and the Small Plant Closure Program will meet or surpass the 11th FYP savings goals. China's appliance standards and labeling program has become very robust. China has greatly enhanced its enforcement of new building energy standards but energy-efficiency programs for buildings retrofits, as well as the goal of adjusting China's economic structure, are failing. It is important to maintain and strengthen the existing energy-saving policies and programs that are successful while revising programs or adding new policy mechanisms to improve the programs that are not on track to achieve the stated goals.     

Evaluating the need for economic support policies in promoting greenhouse gas emission reduction measures in the building sector: The case of Greece

During the last decade the CO₂ emissions from the residential and tertiary sectors have been rising continuously. This is cause for concern but also an area to be targeted for emission reduction measures in national action plans. This paper proposes a methodological framework, using the Greek building sector (characterized by an aging building stock constructed mostly in the period before 1980) as a case study for the examination of the economic attractiveness of possible measures, which incorporates crucial parameters such as local climate, use of buildings, age of building stock, etc. that affect the energy conservation potential and consequently the economic performance of available measures. Utilizing this framework, the approach is able to classify measures into three categories, namely ‘win–win’ cases (i.e. where the implementation of emission reduction measures presents a net economic benefit for end-users), measures that require the implementation of appropriate economic support policies in order to make them economically attractive for end-users, and measures that have excessive cost. The results indicate that the emissions reduction potential of ‘win–win’ cases is significant. They also demonstrate how individual measures can provide significant reductions if carefully targeted economic support policies are applied. Finally, sensitivity analyses performed with respect to the discount rate applied indicate that it has a substantial impact on the economic performance of some measures and consequently on the magnitude of the ‘win–win’ potential associated to emissions reduction.     

Assessment of bottom-up sectoral and regional mitigation potentials

The greenhouse gas mitigation potential of different economic sectors in three world regions are estimated using a bottom-up approach. These estimates provide updates of the numbers reported in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4). This study is part of a larger project aimed at comparing greenhouse gas mitigation potentials from bottom-up and top-down approaches. The sectors included in the analysis are energy supply, transport, industry and the residential and service sector. The mitigation potentials range from 11 to 15 GtCO₂eq. This is 26–38% of the baseline in 2030 and 47–68% relative to the year 2000. Potential savings are estimated for different cost levels. The total potential at negative costs is estimated at 5–8% relative to the baseline, with the largest share in the residential and service sector and the highest reduction percentage for the transport and industry sectors. These (negative) costs include investment, operation and maintenance and fuel costs and revenues at moderate discount rates of 3–10%. At costs below 100 US$/tCO₂, the largest potential reductions in absolute terms are estimated in the energy supply sector, while the transport sector has the lowest reduction potential.     

The energy and environmental impacts of Italian households consumptions: An input–output approach

Promoting sustainable consumption and production patterns is a key challenge for the future, in order to use the Earth resources efficiently, to reduce the greenhouse gas emissions, and to decouple the economic growth from the environmental degradation.New or customized methods have to be applied to support decisions makers in the choice of environmental-friendly products, and to select policy priorities and sustainable strategies.A modified input–output model can aid to analyse the relationships among economic growth, energy consumptions and pollutants, in order to assess the energy and environmental impacts due to the actual production and consumption patterns.The following paper introduces an energy and environmental extended input–output model and combines it with the Life Cycle Assessment (LCA) methodology.The authors apply this model to the Italian context in order to assess the energy and environmental impacts related to the consumptions of the Italian households in the period 1999–2006 and to identify the economic sectors involving the highest impacts.The paper represents one of the first Italian studies aimed at identifying those national economic sectors and final goods and services to be assumed prior in the definition of sustainable production and consumption strategies. Results show that about the 70% of the total energy, needed to meet the household final demand of products, is consumed by the productive sectors. In particular tertiary, “electricity, gas and vapour”, road transports and “food and beverage” sectors are the most contributors, accounting for about 75%.Further, the environmental impact analysis associated to Italian households consumptions is carried out, starting from three different data sources The results point out that, to include emissions arising both from energy and non-energy sources, in the assessment of environmental impacts is of paramount importance to obtain reliable simulations of the link between households consumptions and energy and environmental performances.     

Implications of private sector participation in power generation—a case study from India

India suffers from widespread shortages of electricity supply. These shortages, among others, are detrimental to the economic growth. The prospects for the next decade do not seem to be much brighter. Efforts in expanding generation capacity by the state-owned electric utilities are hampered by severe resource constraints. Against this backdrop, to mobilize additional resources to help bridge the gap in demand and supply, the Government of India formulated a policy in 1991 with the objective to encourage greater investment by private enterprises in the electricity sector. To study the implications of such an initiative on various stakeholders, viz., public utilities, consumers and private sector, the present paper tries to analyse issues like planned rationing, guarantees to private sector, backing down of existing capacity. Using the state of Karnataka (in Southern India) as a case study, the paper develops multiple scenarios using an integrated mixed integer-programming model. The results show the advantage of marginal non-supply (rationing) of electricity in terms of achieving overall effective supply demand matching as well as providing economic benefits to the state that could be generated through cost savings. The results also show the negative impacts of high guarantees offered to the private sector in terms of the opportunity costs of reduced utilization of both the existing and the new public capacity. The estimated generation losses and the associated economic impacts of backing down of existing and new public capacity on account of guarantees are found to be significantly high. For 2011–12, depending on the type of scenarios, the estimated generation and economic losses are likely to be in the range of 3200–10,000 GWh and Rs. 4200–13,600 million respectively. The impact of these losses on the consumers could be in terms of significant increase in energy bills (in the range of 19–40% for different scenarios) due to rise in tariffs.     

Potential of practical implementation of rice straw-based power generation in Thailand

This paper uses life cycle assessment to evaluate the potential of rice straw power plant implementation in Thailand in terms of GHG emission savings from avoided open burning and from implementing rice straw power production, which can substitute that from natural gas. Annually, 8.5–14.3 Mt rice straw burning contributes 5.0–8.6 MtCO₂-eq which could be converted to 786–1325 MW of power, yielding a total greenhouse gas (GHG) reduction of 7.8–13.2 MtCO₂-eq. Moreover, 1090–1837 Mm³ of natural gas could be substituted annually. A total of 25 provinces in central Thailand have potential to generate electricity with a total capacity of 210–292 MW (plant efficiency 20–27%), resulting in an annual GHG emission savings of 2.3–2.6 MtCO₂-eq, and with a provincial capacity of over 20 MW in 6 provinces, 10–20 MW in 7 provinces, 1–10 MW in 6 provinces and less than 1 MW in 6 provinces.     

Energy and economic evaluation of cooling,heating, and power systems based on primary energy

Cooling, Heating, and Power (CHP) systems have the potential to make better use of fuels than other technologies because of their ability to increase the overall thermal energy efficiency. Feasibility of CHP systems is generally driven by economic savings. In addition, economic evaluation of CHP systems is based on site energy use and cost, which could lead to misleading conclusions about energy savings. Since energy savings from CHP systems only occurs in primary energy, the objective of this investigation is to demonstrate that feasibility of CHP systems should be performed based on primary energy savings followed by economic considerations. This paper also evaluates the effect of the power generation unit (PGU) efficiency over the primary energy reduction when a CHP system is utilized. The advantages of operating CHP systems under a primary energy operational strategy, such as the proposed Building Primary Energy Ratio (BPER) strategy, are also discussed. Results show that for some cases economic savings are attained without the corresponding primary energy savings. However, the use of the BPER operational strategy guarantees better energy performance regardless of economic savings. Regarding to the PGU efficiency, an increase of the efficiency reduces the primary energy use more than proportionally. For example, increasing the PGU efficiency from 0.25 to 0.35 (increase of 40%) can reduce the primary energy use from 5.4% to 16% (increase of 200%).     

Thermo-economic analysis of solar powered adsorption heat pump

The economic feasibility of the residential solar thermal (ST) cooling system designed in the companion article [1] is ascertained by comparing it with a solar electric (SE) cooling system, and also with the baseline (i.e., control case), a grid dependent, highest efficiency COP_C = 5.66 heat pump. The economic scenario is analyzed for 24 cities across the southern USA, south of the 37°N. The SE cooling system provides lifecycle (20 year) savings to the homeowner only where electric rates are high and it is heavily subsidized. The overall societal effect (sum of taxpayer funded rebate and homeowner savings) is actually an increased cost everywhere except the California Central Valley, where the net savings is $1500. In the same valley, The ST cooling system provides greater lifecycle savings to the homeowner with more modest subsidies, and the overall societal effect is a benefit, a savings of $3600. The far and away best location for a ST system is Hawaii, where it affords homeowner savings of $9900 and societal savings of $7600.     

Energy,exergy and economic analysis of industrial boilers

In this paper, the useful concept of energy and exergy utilization is analyzed, and applied to the boiler system. Energy and exergy flows in a boiler have been shown in this paper. The energy and exergy efficiencies have been determined as well. In a boiler, the energy and exergy efficiencies are found to be 72.46% and 24.89%, respectively. A boiler energy and exergy efficiencies are compared with others work as well. It has been found that the combustion chamber is the major contributor for exergy destruction followed by heat exchanger of a boiler system. Furthermore, several energy saving measures such as use of variable speed drive in boiler's fan energy savings and heat recovery from flue gas are applied in reducing a boiler energy use. It has been found that the payback period is about 1 yr for heat recovery from a boiler flue gas. The payback period for using VSD with 19 kW motor found to be economically viable for energy savings in a boiler fan.     

A methodology for analysis of impacts of grid integration of renewable energy

Present electricity grids are predominantly thermal (coal, gas) and hydro based. Conventional power planning involves hydro-thermal scheduling and merit order dispatch. In the future, modern renewables (hydro, solar and biomass) are likely to have a significant share in the power sector. This paper presents a method to analyse the impacts of renewables in the electricity grid. A load duration curve based approach has been developed. Renewable energy sources have been treated as negative loads to obtain a modified load duration curve from which capacity savings in terms of base and peak load generation can be computed. The methodology is illustrated for solar, wind and biomass power for Tamil Nadu (a state in India). The trade-offs and interaction between renewable sources are analysed. The impacts on capacity savings by varying the wind regime have also been shown. Scenarios for 2021–22 have been constructed to illustrate the methodology proposed. This technique can be useful for power planners for an analysis of renewables in future electricity grids.