Matching Western US electricity consumption with wind and solar resources

The variability of wind and solar is perceived as a major obstacle in employing otherwise abundant renewable energy resources. On the basis of the available geographically dispersed data for the Western USA, we analyze to what extent the geographic diversity of these resources can offset their variability. We determine the best match to loads in the western portion of the USA that can be achieved with wind power and photovoltaics (PV) with no transmission limitations. Without storage and with no curtailment, wind and PV can meet up to 50% of loads in Western USA. It is beneficial to build more wind than PV mostly because the wind contributes at night. When storage is available, the optimal mix has almost 75% as much nominal PV capacity as wind, with the PV energy contribution being 32% of the electricity produced from wind. With only 10 GW of storage (twice the pumped hydro storage capacity that already exists in the Western Electric Coordinating Council), up to 82% of the load can be matched with wind and PV, while in the same time curtailing just 10% of the renewable energy throughout the year. Copyright © 2012 John Wiley & Sons, Ltd.     

A computational tool for evaluating the economics of solar and wind microgeneration of electricity

This paper presents a method, implemented as a freely available computer programme, which is used to estimate the economics of renewable microgeneration of electricity from wind and solar energy sources. A variety of commercial small wind turbines and photovoltaic (PV) panels are considered and combined with raw energy data gathered from a variety of locations. Both residential and holiday home user profiles are available and options are selectable concerning feed-in tariffs (if available), government incentive schemes and the cost of capital borrowing. The configuration of the generation setup, which can consist of wind, PV and combination of wind/PV, is fully selectable by the user, with a range of appropriate default data provided. A numerical example, based on Irish data, is presented, which suggests that payback periods for solar and wind microgeneration systems can vary greatly (2.5–500 years), depending on the location, installation and economic variables.     

Overcoming the lock-out of renewable energy technologies in Spain: The cases of wind and solar electricity

This paper applies an evolutionary economics framework to analyse the factors leading to lock-out of renewable energy technologies (RETs). The cases of wind and solar photovoltaics (PV) in Spain are empirically analysed. The paper shows that a wide array of interrrelated factors (technoeconomic characteristics of technology components, system-level infrastructure and institutional factors) can create both barriers to the wide diffusion of RETs and can also be drivers that foster an escape from a lock-in situation. Based on this analysis, the paper suggests several policy measures which may help to overcome the lock-out of promising renewable energy technologies.     

Conceptualizing and evaluating best practices in electricity and water regulatory governance

This article presents a preliminary conceptual framework that scholars and analysts can use to evaluate regulatory systems in the provision of water and electricity services. We propose an integrative evaluative framework combining regulatory governance and regulatory substance metrics to assess regulatory effectiveness in relation to performance based outcomes in water and energy services provision. We identify eight structural based elements as necessary for effective governance in addition to two output attributes. We then identify twelve components that comprise regulatory substance for the energy and water sectors. We lastly suggest quantitative and qualitative metrics for assessing specific sector outcomes. While we recognize that issues associated with outcomes are ubiquitous to both the water and energy sectors, the metrics necessary to evaluate performance and outcomes are sectorally specific. The novelty of our study is that it does not exempt issues of sustainability and equity from notions of effective regulation. Our framework simultaneously looks at regulatory outcomes and governance at micro (industry), meso (provincial/state) and macro (national) levels. Lastly, it highlights the importance of a mixed methods approach that combines quantitative and qualitative metrics.     

A reduced-form approach for representing the impacts of wind and solar PV deployment on the structure and operation of the electricity system

In many climate change mitigation scenarios, integrated assessment models of the energy and climate systems rely heavily on renewable energy technologies with variable and uncertain generation, such as wind and solar PV, to achieve substantial decarbonization of the electricity sector. However, these models often include very little temporal resolution and thus have difficulty in representing the integration costs that arise from mismatches between electricity supply and demand. The global integrated assessment model, MESSAGE, has been updated to explicitly model the trade-offs between variable renewable energy (VRE) deployment and its impacts on the electricity system, including the implications for electricity curtailment, backup capacity, and system flexibility. These impacts have been parameterized using a reduced-form approach, which allows VRE integration impacts to be quantified on a regional basis. In addition, thermoelectric technologies were updated to include two modes of operation, baseload and flexible, to better account for the cost, efficiency, and availability penalties associated with flexible operation. In this paper, the modeling approach used in MESSAGE is explained and the implications for VRE deployment in mitigation scenarios are assessed. Three important stylized facts associated with integrating high VRE shares are successfully reproduced by our modeling approach: (1) the significant reduction in the utilization of non-VRE power plants; (2) the diminishing role for traditional baseload generators, such as nuclear and coal, and the transition to more flexible technologies; and (3) the importance of electricity storage and hydrogen electrolysis in facilitating the deployment of VRE.     

An optimal mix of solar PV,wind and hydro power for a low-carbon electricity supply in Brazil

Brazil has to expand its power generation capacities due to significant projected growth of demand. The government aims at adding hydropower capacities in North–Brazil, additional to wind and thermal power generation. However, new hydropower may affect environmentally and socially sensitive areas in the Amazon region negatively while thermal power generation produces greenhouse gas emissions. We therefore assess how future greenhouse gas emissions from electricity production in Brazil can be minimized by optimizing the daily dispatch of photovoltaic (PV), wind, thermal, and hydropower plants. Using a simulation model, we additionally assess the risk of loss of load. Results indicate that at doubled demand in comparison to 2013, only 2% of power production has to be provided by thermal power. Existing reservoirs of hydropower are sufficient to balance variations in renewable electricity supply at an optimal mix of around 37% of PV, 9% of wind, and 50% of hydropower generation. In a hydro-thermal only scenario, the risk of deficit increases tenfold, and thermal power production four-fold. A sensitivity analysis shows that the choice of meteorological data sets used for simulating renewable production affects the choice of locations for PV and wind power plants, but does not significantly change the mix of technologies.     

Greenhouse gas emissions reduction by use of wind and solar energies for hydrogen and electricity production: Economic factors

This study addresses economic aspects of introducing renewable technologies in place of fossil fuel ones to mitigate greenhouse gas emissions. Unlike for traditional fossil fuel technologies, greenhouse gas emissions from renewable technologies are associated mainly with plant construction and the magnitudes are significantly lower. The prospects are shown to be good for producing the environmentally clean fuel hydrogen via water electrolysis driven by renewable energy sources. Nonetheless, the cost of wind- and solar-based electricity is still higher than that of electricity generated in a natural gas power plant. With present costs of wind and solar electricity, it is shown that, when electricity from renewable sources replaces electricity from natural gas, the cost of greenhouse gas emissions abatement is about four times less than if hydrogen from renewable sources replaces hydrogen produced from natural gas. When renewable-based hydrogen is used in a fuel cell vehicle instead of gasoline in a IC engine vehicle, the cost of greenhouse gas emissions reduction approaches the same value as for renewable-based electricity only if the fuel cell vehicle efficiency exceeds significantly (i.e., by about two times) that of an internal combustion vehicle. It is also shown that when 6000 wind turbines (Kenetech KVS-33) with a capacity of 350 kW and a capacity factor of 24% replace a 500-MW gas-fired power plant with an efficiency of 40%, annual greenhouse gas emissions are reduced by 2.3 megatons. The incremental additional annual cost is about $280 million (US). The results provide a useful approach to an optimal strategy for greenhouse gas emissions mitigation.     

Optimal electricity market for wind power

This paper is about electricity market operation when looking from the wind power producers’ point of view. The focus in on market time horizons: how many hours there is between the closing and delivering the bids. The case is for the Nordic countries, the Nordpool electricity market and the Danish wind power production. Real data from year 2001 was used to study the benefits of a more flexible market to wind power producer. As a result of reduced regulating market costs from better hourly predictions to the market, wind power producer would gain up to 8% more if the time between market bids and delivery was shortened from the day ahead Elspot market (hourly bids by noon for 12–36 h ahead). An after sales market where surplus or deficit production could be traded 2 h before delivery could benefit the producer almost as much, gaining 7%.     

Advances in solar thermal electricity technology

Various advanced solar thermal electricity technologies are reviewed with an emphasis on new technology and new market approaches.In single-axis tracking technology, the conventional parabolic trough collector is the mainstream established technology and is under continued development but is soon to face competition from two linear Fresnel reflector (LFR) technologies, the CLFR and Solarmundo. A Solarmundo prototype has been built in Belgium, and a CLFR prototype is awaiting presale of electricity as a commercial plant before it can be constructed in Queensland. In two-axis tracking technologies, dish/Stirling technologies are faced with high Stirling engine costs and emphasism may shift to solarised gas micro-turbines, which are adapted from the small stationary gas turbine market and will be available shortly at a price in the US$1 ppW range. ANU dish technology, in which steam is collected across the field and run through large steam turbines, has not been commercialised. Emphasis in solar thermal electricity applications in two-axis tracking systems seems to be shifting to tower technology. Two central receiver towers are planned for Spain, and one for Israel. Our own multi-tower solar array (MTSA) technology has gained Australian Research Council funding for an initial single tower prototype in Australia of approximately 150 kW(e) and will use combined microturbine and PV receivers. Non-tracking systems are described of two diverse types, Chimney and evacuated tubes. Solar chimney technology is being proposed for Australia based upon German technology. Air is heated underneath a large glass structure of about 5 km in diameter, and passes up a large chimney through a wind turbine near the base as it rises. A company Enviromission Ltd. has been listed in Australia to commercialise the concept. Evacuated tubes are growing rapidly for domestic hot water heating in Europe and organic rankine cycle engines such as the Freepower 6 kW are being considered for operation with thermal energy developed by evacuated tube and trough systems. These may replace some PV in medium sized applications as they offer potential for inexpensive pressurised water storage for 24 h operation, and backup by fuels instead of generators. In the medium term there is a clear trend to creation of smaller sized systems which can operate on a retail electricity cost offset basis near urban and industrial installations. In the longer term large low cost plants will be necessary for large scale electricity and fuels production. Retrofit central generation solar plants offer a cost effective transition market which allows increased production rates and gradual cost reduction for large solar thermal plant. In the paper the author describes current funding systems in Europe, Australia, and the USA, and makes suggestions for more effective programmes of support.     

Relation between concentration and acceptance in solar collectors

The maximum concentration ratio has been derived by Winston for optical systems having an angular acceptance described by a step function. In this paper a more comprehensive relation between maximum concentration ratio and angular acceptance is obtained. This relation is valid for any acceptance function; the proof is based on thermodynamics and is valid for large angles as well.

The total energies collected yearly by concentrators having different acceptance functions are compared.     

Realistic generation cost of solar photovoltaic electricity

Solar photovoltaic (SPV) power plants have long working life with zero fuel cost and negligible maintenance cost but requires huge initial investment. The generation cost of the solar electricity is mainly the cost of financing the initial investment. Therefore, the generation cost of solar electricity in different years depends on the method of returning the loan. Currently levelized cost based on equated payment loan is being used. The static levelized generation cost of solar electricity is compared with the current value of variable generation cost of grid electricity. This improper cost comparison is inhibiting the growth of SPV electricity by creating wrong perception that solar electricity is very expensive. In this paper a new method of loan repayment has been developed resulting in generation cost of SPV electricity that increases with time like that of grid electricity. A generalized capital recovery factor has been developed for graduated payment loan in which capital and interest payment in each installment are calculated by treating each loan installment as an independent loan for the relevant years. Generalized results have been calculated which can be used to determine the cost of SPV electricity for a given system at different places. Results show that for SPV system with specific initial investment of 5.00 $/kWh/year, loan period of 30 years and loan interest rate of 4% the levelized generation cost of SPV electricity with equated payment loan turns out to be 28.92 ¢/kWh, while the corresponding generation cost with graduated payment loan with escalation in annual installment of 8% varies from 9.51 ¢/kWh in base year to 88.63 ¢/kWh in 30th year. So, in this case, the realistic current generation cost of SPV electricity is 9.51 ¢/kWh and not 28.92 ¢/kWh. Further, with graduated payment loan, extension in loan period results in sharp decline in cost of SPV electricity in base year. Hence, a policy change is required regarding the loan repayment method. It is proposed that to arrive at realistic cost of SPV electricity long-term graduated payment loans may be given for installing SPV power plants such that the escalation in annual loan installments be equal to the estimated inflation in the price of grid electricity with loan period close to working life of SPV system.     

The potential of wind electricity generation in Bangladesh

The hourly wind speed data of the coastal station Chittagong have been collected for the years 1978–1981. From the hourly average wind speed, the hourly and monthly energy outputs were computed for three commercial machines (22 kW, 16 kW and 4 kW) having different cut-in wind speed. The 22 kW machine was found to produce higher energy output per m² than the other two for our energy regime. The hourly and monthly energy variation of the 22 kW machine was studied and the cost per kWh of energy produced by this machine was obtained. Considering the wind speed distribution of Bangladesh, it appears that a wind machine in combination with a conventional diesel back up system will be economically viable for electricity generation in the off-shore islands but not in inland locations.     

Integration of wind power in the liberalized Dutch electricity market

Wind power is becoming a large‐scale electricity generation technology in a number of European countries, including the Netherlands. Owing to the variability and unpredictability of wind power production, large‐scale wind power can be foreseen to have large consequences for balancing generation and demand in power systems. As an essential aspect of the Dutch market design, participants are encouraged to act according to their energy programs, as submitted day‐ahead to the system operator. This program responsibility shifts the burden of balancing wind power away from the system operator to the market. However, the system operator remains the responsible party for balancing any generation/load imbalances that may still be arising in real time. In this article, features that are unique for the Dutch market design are presented and their implications on the system integration of wind power are investigated. It is shown that the Dutch market design penalizes the intermittent nature of wind power. A discussion of opportunities and threats of balancing wind power by use of market forces is provided. Last, an outline is given of future work. Copyright © 2006 John Wiley &Sons, Ltd.     

A probabilistic method for calculating the usefulness of a store with finite energy capacity for smoothing electricity generation from wind and solar power

This paper describes a novel method of modelling an energy store used to match the power output from a wind turbine and a solar PV array to a varying electrical load. The model estimates the fraction of time that an energy store spends full or empty. It can also estimate the power curtailed when the store is full and the unsatisfied demand when the store is empty. The new modelling method has been validated against time–stepping methods and shows generally good agreement over a wide range of store power ratings, store efficiencies, wind turbine capacities and solar PV capacities.Example results are presented for a system with 1 MW of wind power capacity, 2 MW of photovoltaic capacity, an energy store of 75% efficiency and a range of loads from 0 to 3 MW average.     

Effect of wind on solar distillation

A study has been made of roof type solar stills under forced convection conditions. Since the roof type solar still has two inclined surfaces and two vertical surfaces, two arrangements of flow — one parallel to the inclined surfaces of the cover and one parallel to the vertical surfaces of the cover — are investigated. A theoretical equation which gives the heat transfer coefficient for both the inclined and vertical surfaces of the cover is derived. The effect of water and ambient air temperatures, wind velocity, and angle of inclination of the cover on the performance of the still is shown by means of tables and graphs.     

风压对太阳能热风发电系统的影响分析

根据太阳能热风发电系统的工作特征,以内蒙古乌海金沙沙漠太阳能热风发电系统为模型,模拟计算了不同形式的太阳能热风发电系统;对比不同系统内的气流分布,研究讨论了风压对气流流动和气流速度大小的影响。模拟结果表明:半圆形集热棚系统更具优势,其利用率较高,塔囱底部的平均气流速度可达24.38 m/s。该研究分析为乌海金沙沙漠太阳能热风发电站的建设提供了技术指导。     

Estimating the value of wind energy using electricity locational marginal price

There is an increasing interest in adding renewables such as wind to electricity generation portfolios in larger amounts as one response to concern about atmospheric carbon emissions from our energy system and the resulting climate change. Most policies with the aim of promoting renewables (e.g., RPS, FIT) do not explicitly address siting issues, which for wind energy are currently approached as the intersection of wind resource, land control, and transmission factors. This work proposes the use of locational marginal price (LMP), the location and time specific cost of electricity on the wholesale market, to signal locations where generation can address electricity system insufficiency. After an examination of the spatial and temporal behavior of LMP in Michigan over the first two years of wholesale market operation, this work combines LMP with wind speed data to generate a value metric. High value sites in Michigan tend to be sites with higher wind speeds, with the bulk of value accruing in the fall and winter seasons.     

Assessment of solar electricity production in the United Arab Emirates

In this work the possible large-scale integration of photovoltaic (PV) systems and parabolic trough concentrated solar power (CSP) technologies in the United Arab Emirates (UAE) power system is investigated in technical, economic and environmental terms. The analysis takes into account the available solar potential for UAE and in particular for the Emirate of Sharjah. In order to identify the least-cost feasible option for each renewable energy source for power-generation (RES-E) technology, a parametric analysis is carried out by varying each RES-E candidate system capital cost. From the analysis it is evident that an alternative cost-effective technology to the installation of a 50 MWp PV system might be the utilisation of a 50 MWe parabolic trough CSP system with either a 14.5 h thermal storage system or a 24/7 operation. The advantages of the latter are the dispatchability and the increased electricity output due to the utilisation of a thermal storage system, which leads to higher amounts of annual CO₂ avoided emissions. However, the electricity selling prices are higher than the current UAE electricity tariffs; therefore, for the promotion of solar RES-E technologies in the UAE, relevant financial supporting mechanisms need to be developed such as feed-in tariffs or feed-in premiums.