The impact of retail rate structures on the economics of commercial photovoltaic systems in California

This article examines the impact of retail electricity rate design on the economic value of grid-connected photovoltaic (PV) systems, focusing on commercial customers in California. Using 15-min interval building load and PV production data from a sample of 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial-customer retail electricity rates currently offered in the state. Across all combinations of customers and rates, we find that the annual bill savings from PV, per kWh generated, ranges from $0.05 to $0.24/kWh. This sizable range in rate-reduction value reflects differences in rate structures, revenue requirements, the size of the PV system relative to building load, and customer load shape. The most significant rate design issue for the value of commercial PV is found to be the percentage of total utility bills recovered through demand charges, though a variety of other factors are also found to be of importance. The value of net metering is found to be substantial, but only when energy from commercial PV systems represents a sizable portion of annual customer load. Though the analysis presented here is specific to California, our general results demonstrate the fundamental importance of retail rate design for the customer-economics of grid-connected, customer-sited PV.     

The impact of rate design and net metering on the bill savings from distributed PV for residential customers in California

Net metering has become a widespread mechanism in the U.S. for supporting customer adoption of distributed photovoltaics (PV), but has faced challenges as PV installations grow to a larger share of generation in a number of states. This paper examines the value of the bill savings that customers receive under net metering, and the associated role of retail rate design, based on a sample of approximately two hundred residential customers of California's two largest electric utilities. We find that the bill savings per kWh of PV electricity generated varies by more than a factor of four across the customers in the sample, which is largely attributable to the inclining block structure of the utilities' residential retail rates. We also compare the bill savings under net metering to that received under three potential alternative compensation mechanisms, based on California's Market Price Referent (MPR). We find that net metering provides significantly greater bill savings than a full MPR-based feed-in tariff, but only modestly greater savings than alternative mechanisms under which hourly or monthly net excess generation is compensated at the MPR rate.     

Compensating customer-generators: a taxonomy describing methods of compensating customer-generators for electricity supplied to the grid

The increasing popularity of on-site power generation is driving the demand for methods to compensate customer-generators that supply electricity to the grid. Although many practices exist for providing such compensation, confusion surrounds the terms often used to describe such practices (notably, net metering and net billing). To help clarify this situation, the following paper proposes a taxonomy that distinguishes between 16 distinct compensation practices.     

油田供配电系统矿、队分级计量管理实践

油田供配电系统矿、队分级计量管理,在保证"零投入"的前提下,针对错综复杂的供电网络,以"庞大系统区块化、交叉供电简单化、特殊问题具体化、计量采取组合化"为思路,在厂、矿这一层次,将庞大的供电网络,利用"划分、劈分、再组合"方法,喇嘛甸油田实现了四个采油矿及试验大队的电力分矿计量。在矿、队这一层次,实施"两分一控"节电管理法,将电力消耗指标分解到小队、班组进行节奖超罚,充分调动了全体员工参与节能降耗工作的积极性。     

Coal power overcapacity and investment bubble in China during 2015–2020

Electricity consumption growth in China has experienced radical adjustment from high speed to medium speed with the advent of new economy normal. However, the investment enthusiasm on coal power remains unabated and leads to continuous operation efficiency deterioration in recent years. In this paper, we quantify the rational capacity and potential investment of coal power in China during the 13th FYP period (2016–2020). By employing power planning model and fully considering the power sector's contribution in the 15% non-fossil primary energy supply target by 2020, we estimate that the reasonable capacity addition space of coal power ranges between 50 GW and 100 GW, depending on the expected range of demand growth. We find that if all the coal power projects submitted for Environmental Impact Assessment (EIA) approval were put into operation in 2020, capacity excess would reach 200 GW. Such huge overcapacity will bring forth disastrous consequences, including enormous investment waste, poor economic performance of generators and more importantly, delay of low-carbon energy transition. Finally, policy recommendations are proposed to address this issue.     

Comparative analysis of different supporting measures for the production of electrical energy by solar PV and Wind systems: Four representative European cases

In the 9th of March 2007, the European Council decided a fixing goal of 20% contribution of the renewable energy sources (RES) on the total European electric energy production in 2020.In order to reach such an ambitious goal, all the European countries are adopting different support policies for encouraging the installations of RES-based generation systems.In this paper, after a brief review on the main support policies for RES in Europe, the specific situations of four representative countries (France, Germany, Italy and Spain) are examined, with the purpose of putting into evidence the main differences in the support policies adopted for Photovoltaic (PV) and Wind systems.In particular, a comparison based on the calculation of the pay-back-period (PBP), the net present value (NPV) and the internal rate of return (IRR), for different sized PV and Wind systems, shows that in some situations a support policy can be not convenient for the owner of the RES-based generation system and that, in many cases, the differences between the way of implementation of the same support policy in different countries, can give place to significantly different results.     

Examining wind quality and wind power prospects on Fiji Islands

Wind resource analysis was carried out for two major islands in the Fiji. Wind data from July 1993 to June 2005 from NASA data base was analysed. Annual seasonal variation in wind speed, direction and power density were analysed for various locations. The average yearly wind speed for Fiji is between 5 and 6 m/s with average power density of 160 W/m². Site specific validation showed no significant relationship between NASA and experimental data. The wind resource at Laucala Bay has a power density of 131 W/m² at 55 m. The expected annual energy produced from a 275 kW GEV Vergnet wind turbine is 344 MWh. The capacity factor of the turbine is expected to be 14.3% with an overall efficiency of 37%. The electricity generated would cost $FJ 0.27 per kWh. The system will payback its worth in 12.2 years.     

A systems approach for sizing a stand-alone residential PEMFC power system

Polymer electrolyte membrane fuel cells (PEMFCs) show great promise in portable, automotive, and stationary applications. They have reached the test and demonstration phase in automotive and power markets today. This paper is focused on a stand-alone residential PEMFC power system that provides the electricity needs of the house. A novel stochastic sizing methodology is developed that considers both fuel cell system dynamics and residential load dynamics in overall system sizing for the stand-alone residential fuel cell power system. Understanding the nature of demand side is critical in stand-alone system sizing. Thus, experimental measurements have been completed to capture the load side dynamics in detail. No such data is found in the current literature. The Threshold Bootstrap method is used to model the residential load demand and to produce many realistic load profiles. Matlab/Simulink is used to run system simulations to determine system sizes based on parameters defined through a designed experiment. Comparison between the proposed sizing method and a possible worst case scenario sizing is given. The new sizing methodology can be used together with sophisticated demand analysis programs to obtain customized sizing for each user as stand-alone power systems become more viable.     

Social norms,trust and control of power theft in Uganda: Does bulk metering work for MSEs?

Power theft is still rampant in many developing countries. Governments and utility providers tend to favor technical solutions, neglecting the socio-economic dimension. This article analyzes the interaction between the socio-economic factors trust, informal social norms, awareness and electricity pricing effect and technical control measures in Uganda. After reforming its power sector, Uganda introduced two technical innovations: bulk metering for micro and small enterprises (MSE) and prepaid metering for households. The bulk metering system imposes a strong form of social control among MSEs. Drawing on semi-structured interviews with 29 MSEs and 16 experts in Uganda, this article shows how well bulk metering works in practice. It finds that trust is key in the relations between electricity user and utility provider, between citizens and government overseeing the energy sector as well as within bulk metering groups of MSEs. The electricity price impacts MSEs' ability to pay and to some extent also their willingness to pay. Finally, power theft used to be accepted as an informal social norm. Change is happening, but is currently undermined by corruption and patronage networks in the energy sector and the political system, impacting people's attitude to compliance – regardless of the privatization of the electricity sector.     

Wind to power a new city in Oman

This paper proposes the use of wind power as a source of electricity in a new city being developed in the Duqm area of Oman. Recent wind speed measurements taken at the Duqm metrological station are analyzed to obtain the annual and monthly wind probability distribution profiles represented by Weibull parameters. The monthly average mean wind speed ranges between 2.93 m/s in February and 9.76 m/s in July, with an annual average of 5.33 m/s.A techno-economic evaluation of a wind power project is presented to illustrate the project's viability. Given Duqm's wind profile and the power curve characteristics of a V90-1.8 turbine, an annual capacity factor of 0.36 is expected. For the base-case assumptions, the cost of electricity is about $0.05 and $0.08 per kWh for discount rates of 5% and 10%, respectively. These values are higher than that of the existing generation system, due to the subsidized prices of domestically available natural gas. However, given high international natural gas prices, the country's long-term LNG export obligations, and the expansion of natural gas-based industries, investments in wind power in Duqm can be justified. A feed-in tariff and capital cost allowance policies are recommended to facilitate investments in this sector.     

充分利用清洁燃煤热源供暖能力,缓解燃气短供矛盾

我国北方集中采暖区冬季燃气紧张是全社会关注的热点,本文从政策、技术和经济角度讨论这个问题,认为应充分利用清洁燃煤热源的供暖能力,压减采暖用燃气消耗总量,缓解燃气短供矛盾.第一,挖掘现有燃煤热电厂的供暖能力,调峰、供热并举;第二,充分利用采暖期多种可能方式因地制宜供暖.     

The role of mechanically induced separator creep in lithium-ion battery capacity fade

Lithium-ion batteries are well-known to be plagued by a gradual loss of capacity and power which occur regardless of use and can be limiting factors in the development of emerging energy technologies. Here we show that separator deformation in response to mechanical stimuli that arise under normal operation and storage conditions, such as external stresses on the battery stack or electrode expansion associated with lithium insertion/deinsertion, leads to increased internal resistance and significant capacity fade. We find this mechanically induced capacity fade to be a result of viscoelastic creep in the electrochemically inactive separator which reduces ion transport via a pore closure mechanism. By applying compressive stress on the battery structure we are able to accelerate aging studies and identify this unexpected, but important and fundamental link between mechanical properties and electrochemical performance. Furthermore, by making simple modifications to the electrode structure or separator properties, these effects can be mitigated, providing a pathway for improved battery performance.