Exajoules Research Articles

Energy impacts of envelope tightening and mechanical ventilation for the U.S. residential sector

Effective residential envelope air sealing reduces infiltration and associated energy costs for thermal conditioning, yet often creates a need for mechanical ventilation to protect indoor air quality. This study estimated the potential energy savings of implementing airtightness improvements or absolute standards along with mechanical ventilation throughout the U.S. housing stock. We used a physics-based modeling framework to simulate the impact of envelope tightening, providing mechanical ventilation as needed. There are 113 million homes in the US. We calculated the change in energy demand for each home in a nationally representative sample of 50,000 virtual homes developed from the 2009 Residential Energy Consumption Survey. Ventilation was provided as required by 2010 and proposed 2013 versions of ASHRAE Standard 62.2. Ensuring that all current homes comply with 62.2-2010 would increase residential site energy demand by 0.07quads (0.07 exajoules (EJ)) annually. Improving airtightness of all homes at current average retrofit performance levels would decrease demand by 0.7quads (0.74 EJ) annually and upgrading all homes to be as airtight as the top 10% of similar homes would double the savings, leading to roughly $22 billion in annual savings in energy bills. We also analyzed the potential benefits of bringing the entire stock to airtightness specifications of IECC 2012, Canada's R2000, and passive house standards.

Agriculture and greenhouse gases, a common tragedy. A review

Increased atmospheric concentrations of greenhouse gases has led to global warming and associated climatic changes. The problem has been aggravated by the perception that the atmosphere is an infinite and toll-free resource. The well-known concept proposed by Garrett Hardin—“The Tragedy of the Commons”—highlights the misuse of common resources, which ultimately lead to their depletion. This article emphasizes the relevance of the same concept to the current climatic changes and highlights the impact of agriculture on the environment. The specific focus is on field crop production and livestock husbandry that have resulted in deteriorating environmental services and increased greenhouse gas emissions. Meanwhile, the total amount of energy consumed by these sectors is enormous, encompassing 11 exajoules (EJ) annually. In addition, the article highlights possible impacts of climate change on agricultural productivity. Considering the foreseen growth of the global human population, it is expected that additional pressures will aggravate natural environments. Adoption of recommended management practices is crucial to reverse the environmental footprint of agriculture and lessen its impact on climate change. Regarding croplands, these practices can include reduced tillage systems, crop residue management, improved management of nutrients and pests, cover cropping, agroforestry, biochar application as soil amendment, and utilization of precision agriculture technologies. In the livestock sector, recommended management practices include changes in animals’ diet and appropriate management of manure. Adoption of these practices is also expected to decrease the on-farm and off-farm energy use. To encourage the adoption of these practices, authorities should provide the farmers with incentives, such as payments for improving environmental services. Also, international regulations must be enforced to instigate a notable shift in human diets with the goal of reducing the environmental impact of food production. Judicious implementation of related policies would be crucial for promoting the required links between agricultural production and environmental sustainability.

Demand for mini cars and large cars; decay effects, and gasoline demand in Japan

This article explains why: (a) consumers underinvest in new car fuel economy by opting to buy large vehicles; (b) macro shifts in vehicle classes have occurred in the last decades; and how (c) the effects of vehicle fuel economy and shifts in vehicle type influence the growth path of gasoline demand, which is the key to designing effective energy efficiency goals for transport. From 2008, 1.9EXJ (Exajoules) of energy were consumed in Japan by private vehicles producing 124 MtCO2 emissions. For the period 1980 to 2008, we estimated: (1) gasoline demand for three vehicle sizes; (2) vehicle sales; (3) new car fuel economy changes (the ‘real’ technical change); and (4) vehicle stocks. Using a data sample for 1980–2008 we found that: (a) in the short term consumers buy fuel economy, that is sales of mini and small cars increase, but this is not sustained in the long term: and (b) consumers increasingly traded in their cars for larger cars. A further finding was that gasoline demand is projected to increase to 2.3EXJ by 2035, even with a growing number of mini cars. The policy implication is clear: Japan’s policy to reduce oil dependency to 80% by 2030 is in peril as long as buyers prefer larger cars and drive ever longer distances.

Benchmarking the energy use of energy-intensive industries in industrialized and in developing countries

Improved energy efficiency is among the key measures for CO 2 emission abatement in the industry. Energy benchmark curves provide data measured at individual plants and they offer a basis to estimate the sectoral energy efficiency improvement potentials (IP) compared to a best practice technology (BPT) currently in operation worldwide. In this paper, we estimate the BPT energy use of 17 industry sectors based on such curves or energy indicators prepared at country-level. We compare BPT data with current energy use to estimate the IP. According to our analysis, BPT offers improvement potentials of 27 ± 8% worldwide. This is equivalent to 32.5 ± 9.6 EJ (exajoules) of final energy savings worldwide, of which three-quarters can be achieved in developing countries. Due to lack of benchmark curves and limited data availability for developing countries, our results include uncertainties. We used literature data at country-level and international energy statistics to fill data gaps and to develop energy indicators. Quality of these data should be improved and benchmark data needs to be collected for more sectors. By doing so, energy benchmarking could become a key tool to estimate energy saving potentials and energy indicators could serve as strong supplementary methodology.

Assessing Environmental Impacts Embodied in Manufacturing and Labor Input for the China−U.S. Trade

Previous studies on environmental impacts embodied in trade have paid little attention to the impacts of labor input, or environmental overhead of labor input (EOLI). EOLI occurs to support lifestyles both in the purchase of goods and services and in the consumption of fuels and electricity by workers. This research investigates both supply chain manufacturing and EOLI energy use and carbon dioxide (CO(2)) emissions embodied in the 2002 China-U.S. trade. EOLI is substantial in scale: 24% of manufacturing energy in the U.S. and 6% for China. The higher share of EOLI in the U.S. is the result of higher energy use to support worker lifestyles. Analysis shows China's EOLI is dominated by the manufacturing of products consumed by workers, while EOLI on the U.S. side is primarily from workers' direct consumption. The total manufacturing and EOLI energy and CO(2) embodied in the eastbound trade from China to the U.S. are 6.5 exajoules (EJ) of energy (6% EOLI) and 440 million tons (Mt) of CO(2) (8% EOLI). The total manufacturing and EOLI energy and CO(2) embodied in the westbound trade from the U.S. to China are 424 petajoules (PJ) of energy (19% EOLI) and 25.3 Mt of CO(2) (21% EOLI).

Scenarios of global bioenergy production: The trade-offs between agricultural expansion, intensification and trade

Increased future demands for food, fibre and fuels from biomass can only be met if the available land and water resources on a global scale are used and managed as efficiently as possible. The main routes for making the global agricultural system more productive are through intensification and technological change on currently used agricultural land, land expansion into currently non-agricultural areas, and international trade in agricultural commodities and processed goods. In order to analyse the trade-offs and synergies between these options, we present a global bio-economic modelling approach with a special focus on spatially explicit land and water constraints as well as technological change in agricultural production. For a global bioenergy demand scenario reaching 100 ExaJoule (EJ) until 2055 we derive a required rate of productivity increase on agricultural land between 1.2 and 1.4 percent per year under different land allocation options. A very high pressure for yield increase occurs in Sub-Saharan Africa and the Middle East, even without additional bioenergy demand. Moreover, we analyse the implicit values (shadow prices) of limited water resources. The shadow prices for bioenergy are provided as a metric for assessing the trade-offs between different land allocation options and as a link between the agricultural and energy sector.

Energy and Air Emissions Embodied in China−U.S. Trade: Eastbound Assessment Using Adjusted Bilateral Trade Data

It is critical to understand environmental impacts embodied in the bilateral trade between China and the United States, given the political, economic, and geographical importance of the two countries and the fact that few studies have investigated this before. This article studies the environmental impacts, particularly energy consumption and air emissions, embodied in the eastbound (from China to the U.S.) trade from 2002 to 2007 using an environmental input-output analysis technique and the adjusted bilateral trade data. In general,trade volume increased until the panic of 2008, and shifting trade patterns cause fluctuating embodied energy and air emissions in trade in China. Results show that embodied energy ranges from 7 to 11 exajoule (EJ) and takes about 12-17% of China's energy consumption. Embodied CO2 ranges between 400 and 800 Mt and represents about 8-12% of China's CO2 emissions. SO2 and NOx embodied in the eastbound trade generally grow over this period, from 4.2 to 6.3 Mt and from 1.4 to 2.9 Mt and account for 10-15% and 8-12% of China's total emissions, respectively.

Applying bottom-up analysis to identify the system boundaries of non-energy use data in international energy statistics

Data on the non-energy use of fossil fuels in energy statistics are subject to major uncertainties. We apply a simple bottom-up methodology to recalculate non-energy use for the entire world and for the 50 countries with the highest consumption of fossil fuels for non-energy purposes. We quantify worldwide non-energy use in the year 2000 to be 24±2 exajoules (EJ), thereby accounting for 6% of the global total primary energy supply (TPES). Our bottom-up estimates are in line with data from international energy statistics for the entire world and for 14 individual countries. Our estimates exceed official non-energy use data for 22 countries, whereas they are lower than official data in the case of 14 countries. Inconsistent system boundaries of non-energy use data in international energy statistics can explain parts of the observed deviations. We regard our bottom-up methodology as reliable albeit being attached with uncertainties. We recommend its use for energy statisticians and greenhouse gas (GHG) inventory makers to generate a shortlist of countries, for which efforts should be made to clarify and improve the quality of non-energy use data in national and international energy statistics.

Reducing Industrial Energy Use and CO2 Emissions: The Role of Materials Science

AbstractNearly one-third of the world's energy consumption and 36% of its carbon dioxide (CO2) emissions are attributable to manufacturing industries. However, the adoption of advanced technologies already in commercial use could provide technical energy savings in industry of 27–41 exajoules (EJ), along with a reduction in CO2 emissions of 2.2–3.2 gigatonnes (Gt) per year, about 7–12% of today's global CO2 emissions. Even more significant savings can be attained on the supply side if fuel switching and CO2 capture and storage are considered. However, such changes must start in the coming decade to have a substantial impact by 2050.

The value of energy efficiency programs for US residential and commercial buildings in a warmer world

US residential and commercial buildings were responsible for about 41 exajoules (EJ) of primary energy use per year in 2002, accounting for approximately 9% of the world fossil-fuel related anthropogenic carbon (C) emissions of 6.7 Gt that contribute to climate change. US Government-sponsored building energy efficiency research and implementation programs are focused on reducing energy consumption in US residential and commercial buildings and reducing these carbon (C) emissions. Although not specifically intended for adaptation to a warmer climate and less effective than under today’s cooler climate, these programs also could help reduce energy demand in a future warmer world. Warming scenarios projected by the United Nations Intergovernmental Panel on Climate Change (IPCC) in 2001 imply net overall decreases in both site energy and primary energy consumption in US residential and commercial buildings, largely because of the reduced need for heating. However, there would be as much as a 25% increase in building space cooling demand and a significant part of the increase could be offset by energy-efficiency improvements in buildings. Overall, in the US, buildings-related energy efficiency programs would reduce site energy consumption in buildings in the US by more than 2 EJ in 2020 and primary energy by more than 3.5 EJ, more than enough to offset the projected growth in cooling energy consumption due to climate change and growth in the US building stock. The savings would have an estimated annual net value at 2005 energy prices of between $45.0 and $47.3 billion to consumers.

Screening Analysis for EPACT-Covered Commercial HVAC and Water-Heating Equipment

PNNL, under direction from DOE, conducted a screening analysis to determine the energy savings potential from the efficiency levels for commercial HVAC and water-heating equipment listed in Standard 90.1-1999, as well as the potential from several higher efficiency levels. We estimated the annual energy consumption for each type of equipment, at various efficiency levels, through engineering simulations for seven building types in 11 U.S. locations. We also conducted an economic analysis to identify the efficiency levels that would provide the highest value of economic benefits. From 2004 through 2030, the estimated national energy savings for the equipment meeting the Standard 90.1-1999 efficiency levels is about 3.8 exajoules (EJ) (3.6 quads).1 The total estimated carbon emissions reduction is 52 MMtons.

Greenhouse Gas Emissions in a Dynamics-as-Usual Scenario of Economic and Energy Development

This article describes two greenhouse gas (GHG) emission scenarios covering the period 1990–2100. The first of these, the B2 scenario, is a successful attempt to provide an internally consistent quantification—checked by the computer models Scenario Generator (SG), MESSAGE, MACRO, and MAGICC—of key variables describing a plausible but unremarkable “storyline” that complements the other storylines discussed in this special issue of Technological Forecasting and Social Change. In the B2 scenario global carbon emissions from energy use and industrial sources rise from 6.5 gigatons of carbon (GtC) in 1990 to 14.2 GtC in 2100. Primary energy use climbs from 350 exajoules (EJ) to 1360 EJ. The global primary energy structure shifts away from gas and oil (28% in 2100 compared to 55% in 1990) and toward non-fossil energy sources (50% in 2100 compared in 18% in 1990). The share of coal is 22% in 2100, only four percentage points lower than in 1990. Among regions there are significant variations in the primary energy structure. Synthetic liquid fuel production grows to 330 EJ in 2100, driven largely by assumptions about the long-term decline of oil and a continuation in current trends towards increasingly flexible, convenient, and cleaner forms of final energy. On the global level sulfur emissions decline from 63 megatons of sulfur (MtS) in 1990 to 43 MtS in 2100. Radiative forcing grows by approximately 1% per year from 1990 through 2100. The “best guess” temperature change (assumed climate sensitivity = 2.5°C) associated with this increase in radiative forcing is 2°C in 2100. The B2S550 scenario is a variation of the B2 scenario constrained to stabilize the atmospheric carbon concentration below 550 parts per million by volume (ppmv). Carbon emissions in the B2S550 scenario peak in 2040 at 10.7 GtC, before dropping to 5.5 GtC by 2100. Roughly 40% of the 8.7 GtC difference in 2100 between the B2 scenario and the B2S550 scenario is due to fuel switching, primarily away from coal. 32% is from carbon scrubbing, 14% is due to price-induced energy demand reductions, and 12% is from hydrogen injection into the natural gas system. The B2S550 scenario's radiative forcing in 2100 is 8% lower than that of the B2 scenario, and its best guess temperature change is 0.2°C lower.

Combined heat and power: how much carbon and energy can manufacturers save?

In this paper we analyze the potential for CHP in US manufacturing. We use typical efficiencies of today's available CHP technologies to estimate the technical potential for the frozen technology case. We find that if manufacturers in 1994 had self-generated all their steam and electric needs with existing cost-effective CHP technologies, they could have reduced carbon equivalent (=12/44 carbon dioxide) emissions by up to 30 million metric tons of carbon (MtC) or nearly 20 percent, and energy use by nearly an Exajoule (EJ). With growth in manufacturing and expected improvements in CHP technologies, this technical potential could be much larger. However, without environmental regulatory reform and innovation-oriented utility restructuring policies, actual CHP installed by US manufacturers could fall far short.

Savings from energy-efficient industrialized housing for the U.S.

Yearly and cumulative energy savings in industrialized housing projects are estimated for the period 1995–2030. The sensitivity analysis is based on experimental results and existing market conditions. The cumulative savings in 2030 will be about 12 exajoules (EJ) if the necessary steps toward housing industrialization are taken.

Canadian Natural Gas Export Policies And Prospects

Introduction Over the past 15 years Canada has exported over 13 Tcf [13.6 EJ (exajoules)] of natural gas to the United States but gas exports have been running considerably below authorized levels since 1979. If U.S. gas demand increases, with little change in the gas reserves-to-production ratio (Fig. 1), exports of Canadian gas will probably regain and surpass their earlier levels. The compatibility of gas export pricing rules with those for gas consumed domestically will continue to challenge Canadian government policy. Canadian Gas Reserves Remaining non-frontier established Canadian gas reserves at the end of 1982 were about 84 EJ. National Energy Board procedure limits "remaining reserves" to those with demonstrated viable delivery systems. Very significant quantities of "tight" gas (in place) (as high as 400 EJ) are known to exist in the "Deep Basin" of western Canada. They are also excluded even though a portion may be contiguous to conventional, producible, gas reserves. An improved market situation, in terms of both price and volume as U.S. requirements for Canadian gas accelerate, should elicit 44 to 50 EJ of conventional gas in the next 15years with an expected concentration in the late 19805 and early 1990s. Table 1 breaks out total reserves of gas. Frontier resources are expected to be drawn on as the more accessible non-frontier reserves are depleted. Canada's combined ultimate potential may be as much as 6 times greater than currently established non-frontier reserves of 84 EJ. Domestic Natural Gas Consumption Figure 2 projects trends in Canadian oil, natural gas and electricity shares of secondary energy demand (i.e. energy commodities sought by energy users for consumption as energy by them) to the year 2000. Total annual energy demand growth is expected to continue slower than growth of Real Domestic Product over the balance of this decade as conservation measures contribute to further decline in the energy-output ratio. By the 19905, the effects of the price shocks of the early 19805 should have been absorbed. Barring further major price disruptions, energy demand will begin to track output growth more closely. Both natural gas and electricity shares of the Canadian energy market will almost certainly increase. Most of the increase in the gas portion will come from the penetration of new markets-in Quebec, if the Trans Quebec and Maritimes Pipeline makes natural gas available to regions east of Montreal; in Saskatchewan, due to expansion of the distribution system in rural areas; in the Maritime Provinces, as Sable Island gas comes on stream; and in British Columbia, through possible extension of the natural gas pipeline system to Vancouver Island. By the year 2000, natural gas is anticipated to supply about one-third of the needs of the Canadian energy market compared with 27.5 per cent in 1983 and 20 per cent in 1970. Domestic gas requirements will then be about 2.8 EJ, compared with the current level of about 1.8 EJ.