If seems that no matter who you ask, renewable energy is finally considered a serious answer to several of the world’s most pressing problems – but why? In this report, Anil Cabraal, Sachin Agarwal and Masaki Takahashi look at some of the reasons and discuss the economic feasibility of various electricity generation technologies as well as the implications of these findings for power system planners. Finally, they take a quick look at World Bank plans in this area.The recent report by the Intergovernmental Panel on Climate Change (IPCC) should convince the few remaining skeptics that global warming is a fact, and this, coupled with the increasing convergence of the world’s most influential policy makers that climate change must be dealt with as a top priority are sure to result in another shot in the arm for renewable energy technologies. With the world’s energy needs increasing at a rapid rate, renewable energy and energy efficiency can help in ensuring that these needs are met in an environmentally sustainable manner.
Even prior to the IPCC report, 2006 was a remarkable time for sustainable energy. Record amounts of venture capital flowed into the clean energy sector. Wall Street welcomed clean energy players with successful IPOs, and the popular press ran cover stories and special reports on carbon-free energy options, eco-friendly corporate practices and the greening of America.1 Even Wal-Mart announced several initiatives embracing renewable energy,2 and a powerful coalition of institutional investors continued to ask the world’s largest public companies for information related to their greenhouse gas emissions under the Carbon Disclosure Project.3
After spending the last several decades in relative obscurity, this is an opportune time for renewable energy practitioners to ask themselves some questions. Why is renewable energy becoming an increasingly mainstream option? How prepared are we as practitioners to answer the barrage of feasibility-related questions that are bound to come our way? What is it that we still don’t know?Why renewable energy?
As mentioned, one of the main reasons why renewable energy is an increasingly attractive option is because it helps meet energy demand in an environmentally sustainable manner. But there are several other reasons which make renewable energy an increasingly feasible option.Energy security
The recent volatility in the price of oil and natural gas has caused concern and disruption in both developing and developed countries. The electricity sector has been particularly affected as it remains overexposed to both oil and gas. In a World Bank supported research paper, Shimon Awerbuch and Martin Berger show that renewable energy systems broaden the portfolio of options for electricity resources.4 Renewable energy systems thus reduce the dependence on fuels with significant price volatility and availability concerns.
Awerbuch and Berger argue that the traditional least-cost approach of electricity planning is no longer suitable. According to them, electricity planners now have a wide range of technological and institutional options for generating electricity. Furthermore, the future that they are planning for is more dynamic, complex and uncertain. This makes predicting the long-run, least-cost alternative very difficult. They propose using a portfolio approach to value generating alternatives and energy diversity and security objectives. (The portfolio approach is a standard technique used by financial investors to diversify away idiosyncratic risk and increase expected returns.)
Using the portfolio approach, Awerbuch and Berger challenge the widely held belief that adopting renewable energy targets results in higher generation costs since renewable energy costs more on a stand-alone basis. They say that portfolio-based analyses in the US have indicated that adding PV, wind and other fixed-cost renewable technologies to a fossil generating portfolio lowered the overall generating cost and risk. They explain this as resulting from the portfolio effect.
They then went on and evaluated the EU renewables targets and energy security objectives using a similar approach and discovered that the EU generating mixes are sub-optimal because it is possible to have portfolios with lower costs and risk by including more wind or other fixed-cost renewables. Not only does this reduce energy cost but it also increases energy security. They also show how introducing renewables like wind and geothermal technologies into the electricity generating mix for Mexico can reduce both the cost and the risk of future electricity generation. Thus, there is a possibility that all electricity generating portfolios can reduce costs and risks by including some portion of fixed-cost renewable generation.Economic valuation
Traditional financial analysis is based on discounted cash-flow accounting. This sort of analysis fails to adequately capture the future fuel price risks. It also completely ignores the environmental and health costs of fossil-fuelled power plant emissions. Consequently, most countries utilize modern renewable energy (excluding traditional biomass) in an extremely limited way. Yet, if we consider the life-cycle cost, some renewable energy technologies are already cost competitive with conventional energy sources. Despite this, the potential of these financially viable renewable energy technologies is not fully realized because of a variety of market barriers, such as large public subsidies for conventional fuels (Figure 1), lack of adequate regulatory and legal frameworks in support of renewable energy, and undeserved risk premiums built into renewable energy deals, making access to credit difficult.5
FIGURE 1. Energy subsidies in selected countries (IEA, World Energy Outlook 2006)
If we include the costs of local environmental externalities and global externalities (e.g. through carbon credits) in the economic valuation, as is done in a typical World Bank economic calculation (when projects could benefit form carbon financing), then the economic viability of renewable energy increases. Furthermore, if the diversification value (as discussed above) is also added to the economic cost, then the economically viable optimum quantity of renewable energy increases even more. Such economic analyses have been performed for various renewable energy projects, for example in China, Croatia, Mexico and South Africa, to determine the economically viable optimum quantity of renewable energy and these can be found on the World Bank’s energy website.6Achieving the MDGs
For those of us in the international development sector, the Millennium Development Goals (MDGs) are the ‘Holy Grail’. For a renewable energy practitioner, it is important to know that the international development agenda is driven by the MDGs. The MDGs are eight goals (see boxed text) which the world community (countries, multilateral banks, development agencies, NGOs, United Nations) has set for itself in order to mount a focused fight against poverty. The MDGs grew out of the agreements and resolutions of world conferences organized by the United Nations in the past decade. In September 2000, the 189 member states of the UN unanimously adopted the Millennium Declaration, which outlined these goals. The first seven goals focus the world community’s attention on particular aspects of poverty. The eighth goal focuses on an ideal macroeconomic environment which would facilitate the achievement of the first seven goals. Each of the first seven MDGs has definite quantifiable targets (total 15) and is also time bound. Thus, the MDGs create a sense of urgency. They also come with indicators (48 in total) to monitor progress. Most of the MDGs are supposed to be achieved by 2015.
Geothermal power plant in Northern Negros, Philippines, is receiving carbon credits from carbon funds managed by the World Bank. LASSE RINGIUS, WORLD BANK
Although the MDGs do not specifically mention energy, energy plays an essential role in their achievement. According to the International Energy Agency estimates, in order to meet the MDG poverty-reduction target, modern energy services will have to be provided to an additional 700 million people by 2015. Two very interesting papers highlight the role that energy and renewable energy have to play in achieving the MDGs. The first paper, by the UN, called The Energy Challenge for Achieving the Millennium Development Goals discusses the direct and indirect role that energy can play in achieving each of the eight MDGs.7 For example, the second MDG is to achieve universal primary education. Energy can help achieve this goal by providing after-dusk illumination which will enable students to study. Electrified rural schools and villages also make it easier to attract teachers to rural areas.
Solar PV project in Lao pdr
The second paper – by The Worldwatch Institute – is called Energy for Development: The Potential Role of Renewable Energy in Meeting the Millennium Development Goals.8 This paper says that renewable energy can contribute both directly and indirectly. It contributes directly to poverty alleviation by providing the energy needed for creating businesses and jobs. This turns locally available resources into productive economic assets. The paper also provides several examples of the indirect ways in which renewable energy can help facilitate achieving the MDGs. For example, locally produced biomass reduces expenses and frees up time for learning and income-generating opportunities. Renewable energy for cooking and heating reduces the time that children, especially girls, spend out of school collecting fuel. Renewable energy also contributes to improved health by providing energy to refrigerate medicine, sterilize medical equipment and incinerate medical waste. Thus, the MDGs are also playing a part in creating a more mainstream role for renewable energy.Assessment of various electricity generation technologies
As the excitement over the potential of renewable energy continues to grow, it makes obvious the need for more knowledge. It is essential that both renewable energy practitioners as well as energy planners have a good sense of just exactly when renewable energy is feasible and when is it not. The China study mentioned above underscored the importance of having robust and credible knowledge.
A rural families in Bolivia enjoying electricity services from photovoltaics with support from a project funded by the World Bank and Global Environment Facility, kilian reiche
So far we have been having this discussion using the umbrella term ‘renewable energy’, but, in reality, various renewable energy technologies are as different from one another as nuclear energy is from coal-fired generation. Thus, it is important to get a good sense of which renewable energy technologies are competitive and which are not. Also important to consider are the various configurations: off-grid, mini-grid and grid. Furthermore, any feasibility analysis is extremely sensitive to the time period under consideration, and thus a robust analysis must consider various time period scenarios as well. Anticipating the need for a sophisticated and exhaustive analysis which takes all of the above-mentioned factors into account, the World Bank commissioned a study. This electrification assessment study was undertaken by a team comprising Chubu Electric Power Co Inc, Toyo Engineering Corporation, Princeton Energy Resources International, Energy Technologies Enterprises Corp, Global Energy Associates Inc, and The Energy and Resources Institute.Scope of the study
The study examined power generation technologies across a size range of 50 W to 500 MW organized into three distinct electricity delivery configurations: off-grid, mini-grid and grid (see Table 1). Generation technologies examined included renewable energy technologies (photovoltaics, wind, geothermal, hydro, biomass-electric, biogas-electric); conventional generation technologies (gasoline or diesel generator; oil/gas steam-electric, combustion turbines and combined cycle; coal-fired steam-electric, oil/gas-fired combustion turbine and combined cycle technologies, and coal-fired and oil-fired steam cycle technologies); and emerging technologies (integrated gasification combined cycle, atmospheric fluidized bed combustion, fuel cells and micro-turbines). The economic assessment was performed for three different time periods (2005, 2010 and 2015) in order to incorporate projected cost reductions from scaling-up of emerging technologies. A levelized analysis of capital and generation costs was conducted in economic, rather than financial, terms to allow generic applications of results to any developing country. Capital and generation cost projections incorporated uncertainty analysis, allowing the results to reflect sensitivity to key input assumptions. The study results make it possible to compare the levelized economic costs of electricity technologies over a broad range of deployment modes and demand levels, both at present and in future.
TABLE 1. Representative generation technology options and configurations examined
Methodology of the study
A five-step process comprised the methodology. First, a technology assessment was performed for each candidate generation technology. The assessment covered operating principles, application for electrification purposes, and prospects for performance improvement and capital cost reduction. Next, they did an environmental characterization which focused on typical environmental impacts from normal operations using typical emissions control measures and costs. The assessment assumed use of emissions controls in accordance with World Bank environmental guidelines; these costs were included in the economic assessment. The third step was to do a capital cost assessment using a standard mathematical model and actual cost data (where available) and reflecting typical deployment. Future capital costs of generation were then developed, based on technology forecasts (e.g. learning curves) and incorporating uncertainties in equipment cost, fuel cost and capacity factor. The uncertainty analysis was a parametric analysis of variability in key inputs and generated a band of maximum and minimum costs for each period (2005, 2010 and 2015). Finally, levelized generating costs were calculated using a consistent economic analysis method but differentiated according to deployment conditions. This last step also included an uncertainty analysis on the inputs to the levelized cost calculation, again generating a band of maximum and minimum costs for the 2005, 2010 and 2015 periods. All cost estimates were developed for a single reference location (India) to minimize any site-specific discrepancies when comparing technologies.
Mini-hydro power plant in Sri Lanka, one of over 117 MW of mini-hydro plants, each under 10 MW, receiving financing from the World Bank. An additional loan for another 50 MW was approved in 2007, dominic sansoni, 2002
The study revealed emerging trends in terms of the relative economics of renewable and conventional generation technologies according to size and configuration. In interpreting and applying these findings it should be kept in mind that the assessment effort is a desk study bound by time (technology and prices are not static) and method (it consolidates secondary source information rather than generating new content).Renewable energy is more economical than conventional generation for off-grid (less than 5 kW) applications.
Several renewable energy technologies – wind, mini-hydro and biomass-electric – can deliver the lowest levelized generation costs for off-grid electrification (see Figure 2), assuming availability of the renewable resource. Pico-hydro in particular can deliver electricity for 10-20 cents/kWh, less than one-quarter of the 40-60 cents/kWh for comparably-sized gasoline and diesel engine generators. Even relatively expensive renewable energy technology (solar PV) is comparable in levelized electricity costs to the small fuel-using engine-generators under 1 kW in size.
FIGURE 2. Off-grid forecast generating cost
Several renewable energy technologies are potentially the least-cost, mini-grid generation technology.
Mini-grid applications are village and district-level isolated networks with loads of 5 kW – 500 kW. The assessment results suggest several renewable energy technologies (biomass, geothermal, wind and hydro) may be the most economical generation choice for mini-grids, assuming a sufficient renewable resource is available (see Figure 3). Two biomass technologies – biogas digesters and biomass gasifiers – seem particularly promising due to their high capacity factors and availability in size ranges matched to mini-grid loads. Since so many renewable energy sources are viable in this size range, mini-grid planners should thoroughly review their options to make the best selection.
FIGURE 3. Mini-grid forecast generating costs
Conventional power generation technologies
For the foreseeable future, conventional power generation technologies (open cycle and combined cycle gas turbines, coal- and oil-fired steam turbines) remain more economical for most large grid-connected applications, even with increases in oil price forecasts (see Figure 4). Site-specific considerations such as load profile, demand and cost differentials between oil, natural gas and coal prices determine which configuration is the least expensive. Using super-critical or ultra-supercritical (USC) for very large (over 500 MW) power plants is most cost-effective when fuel prices are high and CO2 reductions are sought.
FIGURE 4. Grid-connected forecast generating costs (cents/kWh)
Two new coal technologies have considerable potential for developing economies
Two new coal-fired power plant technologies – IGCC and AFBC – are attracting considerable attention by planners of large power grids in countries with coal or lignite reserves. AFBC is already commercially available up to 300 MW size and is used widely worldwide, including in China and India. This technology is competitive in situations where low-quality inexpensive fuel is available and when SO2 emission regulations require a wet scrubber. In the 100 MW to 300 MW range, the circulating fluidized bed (CFB) option is preferable. The AFBC option may also be applicable to smaller thermal power plants (under 100 MW) using biomass and municipal solid wastes (MSW). IGCC is in the early commercialization stage and could become a viable and competitive option in the future given its excellent environmental performance (see Figure 4).Implications for power system planners
Power system planners tend to operate on an incremental basis, with new capacity additions selected to accommodate the location and pace of load growth on a least-cost basis. The study suggests that scale is a critical aspect affecting the economics of different generation configurations. When a national or regional grid is developed with sufficient transmission capacity, and incremental load growth is fast, large, central-station gas combined cycle and coal fired power plants would clearly be the least-cost alternatives. However, based on site-specific characteristics, if the size of the grid is limited or the incremental load growth is small, it may make economic sense, reduce financing and construction risk and secure power system stability to add several smaller power stations rather than one very large power station.
A wind farm in Huitengxile in Inner Mongolia, China, with ‘guest’ yurts for tourists in the foreground. The World Bank has financed 220 MW of wind farms in China as well as providing carbon credits for a 100.25 MW wind farm in Huitengxile, dai cunfen, international finance corporation
Furthermore, if local resources such as indigenous coal, gas, biomass or geothermal or wind or hydro are used, this may increase energy security and mitigate some of the uncertainty caused by volatile international fuel prices.More research required
The findings reached by the study suggest that choosing generation technologies and electrification arrangements is becoming a more complicated process. New technologies are becoming more economical and technologically mature, uncertainty in fuel and other inputs is creating increasing risk regarding future electricity costs, and old assumptions about economies of scale in generation may no longer be valid. Although the assessment methods used in the study provided a useful comparison among technologies, there needs to be further refinement in the methodology. That will generate even more confidence in the conclusions reached, which can then become the basis of national or regional electrification plans.
Accounting for the locational and stochastic variability of renewable resources, as well as balancing costs, land costs, labour and transport costs, all need further investigation, as does the method of accounting for the incremental cost of delivering electricity. The need to accommodate environmental externalities in the economic assessment also needs more attention.
Finally, the relative economics of conventional vs. renewable energy is largely driven by forecasts of fuel prices together with certain construction and manufacturing materials prices, such as steel, concrete, glass and silicon. All these commodity prices are increasingly subject to uncertainties and price fluctuations in possibly countervailing directions, which make forecasts of future generation costs extremely uncertain. Since the study was conducted, there have been cost increases in coal-fired power plants, gas and steam turbine prices, wind energy and photovoltaic modules. This will have an impact on the findings of the study.
Cost estimates for electricity from US coal-fired power plants used to hover around the US$1000 per kW mark but were closer to $1400 per kW in 2006. Gas and steam turbine prices have seen more than a 50% increase because of strong demand from oil producing countries. Wind farm bids are coming in at $1700-$2000 compared to much more modest assumptions in study. Recent (2007) bids for World Bank and GEF-financed solar thermal power plants have been about 1.5 times more than estimated costs. Similarly, for photovoltaic modules the study assumes continued decreases in costs of 20% between 2004 and 2015 due to technology advancement and growing production volume; whereas costs have actually been climbing steadily, as shown in Figure 5.
FIGURE 5. Photovoltaic module price trends
In the light of the above, it is obvious that additional work, including use of hedging or other financial risk mitigation instruments, is needed to quantify and reflect these future fuel and commodity price uncertainties as part of the electrification planning process. Following in the footsteps of Awerbuch and others, the World Bank has begun to investigate alternative electric power systems planning models that explicitly incorporate risks and uncertainties in the decision process. A workshop to examine the issues and to develop a plan of action was hosted recently at the World Bank.9Role of the World Bank
The World Bank Group (WBG) is committed to promote not just investments but also adequate policy environments supporting renewable energy. In September 2005, after the Gleneagles G8 summit, the WBG began preparing a Clean Energy and Development Investment Framework. The investment framework covers three inter-related areas.
Pillar 1 focuses on the role of energy for economic growth and development. It includes issues such as access for the poor and poverty reduction. Pillar 2 focuses on the policies and financial requirements to support a transition to a low-carbon economy. Pillar 3 focuses on the need for investments to reduce vulnerability to climate variability, especially for the poor, who suffer the most from this problem. The investment framework is intended to be a vehicle to accelerate investment along each of these three pillars. Renewable energy will be a key ingredient as the WBG moves forward on Pillars 1 and 2.
The WBG has begun implementing the Investment Framework for Clean Energy for Development.10 This offers a structure upon which the global community can direct its support for renewable energy in the coming years. Although this article is focused on renewable energy, from a climate change standpoint we cannot ignore the vast untapped potential of the ‘cheapest’ source of energy – energy efficiency. Renewable energy and energy efficiency development must go hand in hand.
Many children in rural areas do odd jobs to help out their parents during the day. Electricity has allowed them to study at night. One of the successful solar home systems projects supported by the World Bank is in Bangladesh, where 5000 units are being installed every month with over 100,000 units installed to date with financing provided through microfinance institutions. The government has requested further support from the World Bank for 300,000 solar home systems, THE DAILY STAR, DHAKA, BANGLADESH
The growth of the WBG RE and EE portfolio is evidence of this. Since 1990, the WBG has committed more than $10 billion to renewable energy and energy efficiency. Since the Bonn Renewable Energy Conference in 2004, our new renewable energy and energy efficiency commitments have accelerated, reaching $1.13 billion in the past two fiscal years. In fiscal 2006, commitments for new renewable energy and energy efficiency were $668 million, growing at more than double the 20% Bonn growth target.11
Although a lot has been accomplished by the WBG in this area, it is extremely aware that to fully integrate RE and EE into global markets, there are several issues that will need to be addressed. Some of these issues are:
- Increased access to long-term financing to make capital intensive renewable energy technologies financially viable and affordable.
- More effective technology transfer and strengthening the capacity to plan, supply, install and maintain technologies
- Making energy prices reflect full costs of supply and eliminating fuel subsidies
- Reducing perceived risk and high cost of RE/EE transactions
- Improving regulatory and policy frameworks and establishing the enabling legislation
Moving forward, the WBG’s Investment Framework will serve as a platform for assisting partner countries to meet energy demand and incorporate low-carbon technologies such as renewable energy and energy efficiency into their investment strategies.
Anil Cabraal is a Lead Energy Specialist at the World Bank
e-mail: [email protected]
Sachin Agarwal is a consultant to the World Bank;
e-mail: [email protected]
Masaki Takahashi is a Senior Power Engineer in the Energy, Transport and Water Department, Sustainable Development Vice Presidency at the World Bank in Washington DC. The study was managed by Masaki Takahashi.
e-mail: [email protected]
Note: This paper is based on a World Bank study undertaken by a team comprising Chubu Electric Power Co Inc, Toyo Engineering Corporation, Princeton Energy Resources International, Energy Technologies Enterprises Corp, Global Energy Associates Inc and The Energy Research Institute. Funding from the Japan Consultant Trust Fund is acknowledged. The detailed study will be available from the World Bank by July 2007. It is posted on the website, www.worldbank.org/re.Disclaimers
The findings, interpretations and conclusions expressed in this paper are entirely those of the authors and should not be attributed in any manner to the World Bank, to its affiliated organizations or to members of its Board of Executive Directors or the countries they represent. The World Bank does not guarantee the accuracy of the data included in this paper and accepts no responsibility whatsoever for any consequences of their use.References
- Please see the September 2006 Special Issue of Scientific American; the Special Report in the 29 January 2007 issue of BusinessWeek, the Special Report in the 27 January 2007 issue of The Economist; cover story called ‘Green is Good’ in Information Week (March 12, 2007); cover story called ‘Green dreams – The risky boom in the clean-energy business’ in The Economist (18 November 2006); cover story called ‘Go Green. Get Rich.’ in Business 2.0 (January/February 2007); and the Energy Journal Report in The Wall Street Journal (February 12, 2007)
- See Wal-Mart website at www.walmartstores.com/GlobalWMStoresWeb/navigate.do?catg=678
- See Carbon Disclosure Project at www.cdproject.net
- S. Awerbuch, and M. Berger, ‘A Portfolio Approach to Energy Planning in Mexico,’ The World Bank, Washington DC. Report available at www.worldbank.org/retoolkit
- International Energy Agency, ‘World Energy Outlook 2006,’ Paris, France
- Reports available at www.worldbank.org/retoolkit
- UN Energy, ‘The Energy Challenge for Achieving the Millennium Development Goals,’ United Nations, New York, NY. http://esa.un.org/un-energy/pdf/UN-ENRG%20paper.pdf
- The Worldwatch Institute, ‘Energy for Development: The Potential Role of Renewable Energy in Meeting the Millennium Development Goals, Renewable Energy Network for the 21st Century, Paris, France. www.ren21.net
- Donald Hertzmark, ‘Risk Assessment Methods for Power Utility Planning,’ Energy Sector Management Assistance Programme Special Report 001/07, The World Bank, Washington DC, March 2007. www.worldbank.org/re
- The World Bank, ‘An Investment Framework for Clean Energy for Development,’ Washington DC. See http://www.worldbank.org/sustainabledevelopment
- The World Bank, ‘Improving Lives: World Bank Group Progress on Renewable Energy & Energy Efficiency in Fiscal Year 2006,’ Energy and Mining Sector Board, Washington DC, December 2006. http://www.worldbank.org/re
THE EIGHT MILLENNIUM DEVELOPMENT GOALS (MDGS)
- Eradicate extreme poverty and hunger: Energy inputs such as electricity and fuels are essential to generate jobs, industrial activities, transportation, commerce, microenterprises and agriculture outputs. Most staple foods must be processed, conserved and cooked, requiring heat from various fuels.
- Achieve universal primary education: To attract teachers to rural areas electricity is needed for homes and schools. After-dusk study requires illumination. Many children, especially girls, do not attend primary schools because they have to carry wood and water to meet family subsistence needs.
- Promote gender equality and empower women: Lack of access to modern fuels and electricity contributes to gender inequality. Women are responsible for most household cooking and water-boiling activities. This takes time away from other productive activities as well as from educational and social participation. Access to modern fuels eases women’s domestic burden and allows them to pursue educational, economic and other opportunities.
- Reduce child mortality: Diseases caused by unboiled water, and respiratory illness caused by the effects of indoor air pollution from traditional fuels and stoves, directly contribute to infant and child disease and mortality.
- Improve maternal health: Women are disproportionately affected by indoor air pollution and water- and food-borne illnesses. Lack of electricity in health clinics, illumination for night-time deliveries, and the daily drudgery and physical burden of fuel collection and transport all contribute to poor maternal health conditions, especially in rural areas.
- Combat HIV/AIDS, malaria and other diseases: Electricity for communication such as radio and television can spread important public health information to combat deadly diseases. Healthcare facilities, doctors and nurses all require electricity and the services that it provides (illumination, refrigeration, sterilization, etc) to deliver effective health services.
- Ensure environmental sustainability: Energy production, distribution and consumption has many adverse effects on the local, regional and global environment, including indoor, local and regional air pollution, local particulates, land degradation, acidification of land and water, and climate change. Cleaner energy systems are needed to address all of these effects and to contribute to environmental sustainability.
- Develop a global partnership for development: The World Summit for Sustainable Development called for partnerships between public entities, development agencies, civil society and the private sector to support sustainable development, including the delivery of affordable, reliable and environmentally sustainable energy services.
Source: UN Energy, The Energy Challenge for Achieving the Millennium Development Goals, United Nations, New York, NY. http://esa.un.org/un-energy