Management of variable electricity loads in wind – Hydrogen systems: The case of a Spanish wind farm

The main obstacles of most renewable energies are their variability and availability; thus, we propose the ‘hydrogen option’ as a means of energy management, and we study its feasibility in a specific wind farm. The installation will be capable to store electrochemically the surplus energy and return the electricity to the grid during the peak hours. The solution was to connect the system, so that we store the energy as hydrogen when the wind generation exceeds a threshold; this is done by an electrolyzer set, with the appropriate nominal power, where, besides the electrical conversion devices, we have designed a control programme for tuning the voltage and current densities to the optimal operation of the cells. To utilize the hydrogen downstream the storage subsystem, we have selected a fuel-cell and the output is finally converted to the grid requirements.     

An assessment of wind-hydrogen systems for light duty vehicles

A hydrogen economy could offer energy stability, economical, and environmental benefits. In this paper, a hydrogen system based on wind-generated electricity is presented as a viable component in a hydrogen transition strategy. The strengths of a wind-hydrogen system are exhibited in its modular design, exploitation of existing technology, and utilization of a renewable resource. Specifically, a state level assessment of wind power was conducted in order to determine the ability of individual states to meet light-duty vehicle hydrogen fueling demands while utilizing the proposed system. Additionally, analysis related to existing hydrogen resources is presented in order to form a transition scenario.     

Complementarity of hydro and wind power: Improving the risk profile of energy inflows

The complementarity of two renewable energy sources, namely hydro and wind, is investigated. We consider the diversification effect of wind power to reduce the risk of water inflow shortages, an important energy security concern for hydropower-based economic zones (e.g. Québec and Norway). Our risk measure is based on the probability of a production deficit, in a manner akin to the value-at-risk, simulation analysis of financial portfolios. We examine whether the risk level of a mixed hydro-and-wind portfolio of generating assets improves on the risk of an all-hydro portfolio, by relaxing the dependence on water inflows and attenuating the impact of droughts. Copulas are used to model the dependence between the two sources of energy. The data considered, over the period 1958–2003, are for the province of Québec, which possesses large hydro and wind resources.     

Opportunities for hydrogen production in connection with wind power in weak grids

This paper gives an overview of the opportunities that exist for combining wind power and hydrogen (H₂) production in weak grids. It is described how H₂ storage can be applied in both isolated and grid-connected systems, and how the produced H₂ can be utilized for stationary energy supply and/or as a fuel for transportation. The paper discusses the benefits and limitations of the different H₂ storage applications, and presents a logistic simulation model for performance evaluation of wind-H₂ plants. A case study simulating the use of excess wind power in a weak distribution grid to produce H₂ for vehicles has been presented. It is shown that the penetration of wind power can be significantly increased by introducing electrolytic H₂ production as a controllable load. The results also indicate that there are large benefits of using the grid as backup for H₂ production in periods with low wind speed, regarding the H₂ storage sizing and the electrolyser operating conditions.     

Incentive policies for promoting wind power production in Brazil: Scenarios for the Alternative Energy Sources Incentive Program (PROINFA) under the New Brazilian electric power sector regulation

The Alternative Energy Sources Incentive Program (PROINFA) was designed in 2002 to stimulate the electricity generation from three energy sources (wind, biomass and small-scale hydro) in Brazil. The Program was divided into two phases. The first one uses feed-in tariffs for promoting the development of 3300 MW. The second one that was originally based on feed-in tariffs was modified in 2003, in order to be based on biddings for renewables. These biddings are capped to limit their impact on the final electricity tariff. Due to this bound, the highest-cost power option promoted by PROINFA (wind power generation) might have development problems. Simulating different scenarios for the biddings, it was verified that the only way to reach the original goal set by PROINFA (10% of the annual electricity consumption provided by alternative sources up to 2020) and, simultaneously, not overcome the bidding bound is to promote biomass-fired power generation alone, during the Program's second phase. However, this action contradicts one of the targets of the Program, which is to diversify the energy matrix. An alternative option could be biddings for renewables according to specific criteria (complementarities, industrial and technological development and cost), based not only on their cost-effectiveness.     

The homemaker’s hydrogen generator: A report for IAHE student hydrogen design competition 2010

As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe storage. Consequently, the viability of a sustainable hydrogen economy greatly depends on the development of an efficient, cost-effective method of hydrogen production. One model for addressing this challenge is to deploy portable hydrogen generators for the home. The Princeton University Chapter of the International Association for Hydrogen Energy (IAHE-PU) has designed and created a generator that produces hydrogen through water electrolysis and optimizes cost effectiveness and portability while maximizing hydrogen output.For our proof-of-concept, the system utilizes simple household items with a Sharp ND130UJF 130W solar panel. In our design, Ni electrodes submerged in 8 M KOH solution in six glass containers were utilized to power an external circuit. Over 1 h, our system produced 8.61 L of hydrogen gas at an estimated cost of $8.58 per kilogram of hydrogen gas over the 25-year lifetime of the solar panel.     

Electrolysis of black liquor for hydrogen production: Some initial findings

Electrolysis of black liquor, an effluent from paper industry, was carried out and compared with alkaline water electrolysis. Energy efficiency in terms of HHV of hydrogen was found in the range of 84–97% whereas under similar conditions alkaline water electrolysis could not give more than 66% efficiency. Hydrogen evolution in black liquor electrolysis was possible even at an inter electrode potential of 1.17 V but in alkaline water electrolysis there was no hydrogen production below an inter electrode potential of 1.31 V. In addition to this, alkali lignin, amounting to 28–46 mg/mg of hydrogen produced, was separated at anode during black liquor electrolysis, which, on account of its good calorific value, has the potential of significantly improving the overall energy efficiency of the process.     

Life cycle assessment of the electrolytic production and utilization of low carbon hydrogen vehicle fuel

Environmental burdens associated with small scale (40 L hydrogen per minute) production of hydrogen fuel using electrolysis powered by electricity generated from stand-alone wind turbines (30 kW), stand-alone photovoltaic panels (3 kW peak) and UK grid electricity (current and future) has been undertaken. Utilization of fuel within a proton exchange membrane fuel cell passenger vehicle was included and compared to the operation of a petrol vehicle, a fuel cell vehicle fuelled with non-renewable hydrogen, and an electric (battery only) vehicle. The production of renewable hydrogen from wind energy incurs increased climate change burdens compared with extraction and processing of fossil petrol (0.09 mPt compared with 0.07 mPt). However, lower burdens for fossil fuel (1.85 mPt) and climate change (0.26 mPt) are realised by the renewable hydrogen options compared with petrol (4.44 mPt and 0.44 mPt, respectively) following utilization of the fuel due to lower emissions at end use. Utilizing a combination of renewable hydrogen fuelled vehicles and grid powered electric vehicles was considered to be a viable option for meeting UK policy ambitions.     

Hydrogen storage and demand to increase wind power onto electricity distribution networks

An optimal power flow (OPF) methodology is developed to investigate the provision of a demand hydrogen as a means to maximise wind power generation in relation to a constrained electricity network. The use of excess wind energy to generate hydrogen for use as a transport fuel is investigated. Hydrogen demand is included in the objective function of the OPF, and a techno-economic analysis is presented. We conclude that using this method to generate hydrogen increases the utilisation of wind energy and allows for a hydrogen demand to be met at or near to the point of use. The OPF algorithm that has been developed optimises the amount of wind energy utilised, as well as minimising the amount of hydrogen demand not met. The cost at which the hydrogen is produced was found to be dependent on the operating methodology, component capital investment costs, level of hydrogen demand, and storage constraint.     

Control of a grid-assisted wind-powered hydrogen production system

This paper deals with the control of a H₂ production system supplied by wind power and assisted by the grid. The system architecture consists of a pitch-controlled wind turbine coupled through a diode rectifier to an alkaline electrolyzer, which in turn is connected to the electric grid through a fully-controlled bidirectional electronic converter. A control strategy for the electronic converter is proposed to regulate the electrolyzer current at its rated value. Thus, H₂ production efficiency is optimized despite wind power and temperature variability. Control design is based on sliding mode techniques, which are particularly appropriate to control fast switching devices and exhibit strong robustness properties. Additionally, in high wind speeds, a pitch control loop is activated to limit the wind power capture below admissible values.     

Energy consumption and stability of the Ni-Mo electrodes for the alkaline hydrogen production at industrial conditions

Hydrogen production via electrolysis of water from alkaline aqueous electrolytes is a well-established conventional technology. However, the cost of hydrogen produced in such a way is high. To improve this process we have investigated in situ activation with Ni-Mo electrocatalytic material for electrodes. This two d-metal combination possesses one of the highest known activities for the HER. Ni-Mo based catalyst was not applied at industrial applications yet, because under industrial conditions (high temperature and concentrated alkaline solution), permanent destruction of the Ni-Mo alloy coating occurs. The most important result of this study is that the Ni-Mo deposit obtained by in situ activation, under industrial conditions, exhibit long term stability and the electrodes retain their high catalytic performance. The process of adding Ni-Mo activating compounds in situ exhibits savings of the energy consumption that can go beyond 20% in some cases.     

Raising efficiency of hydrogen generation from alkaline water electrolysis – Energy saving

This paper presents an attempt to make the alkaline electrolytic production of hydrogen more efficient by adding in situ activating compounds in ionic and complex form. Cobalt and tungsten based ionic activators (i.a.), added directly into the electrolyte during the electrolytic process, reduce energy requirements per mass unit of hydrogen produced for about 15%, compared to non-activated system, for a number of current densities in a wide temperature range. Energy saving is higher at higher temperatures and on higher current densities. Structural and morphological characteristic of deposit formed on the cathode during the electrolytic process reveal very interesting and unique pattern with highly developed surface area and uniform distribution of the pores. Obtained deposit also exhibit a long term stability.     

Cobalt-chrome activation of the nickel electrodes for the HER in alkaline water electrolysis – Part II

Catalyst based on cobalt and chrome was investigated as cathode material for hydrogen production process via water electrolysis. Electrocatalytic efficiency of proposed system was studied using quasi-potentiostatic, galvanostatic and impedance spectroscopy techniques of the catalyst obtained by in situ electrodeposition in an alkaline, 6 M KOH, electrolyser. In accordance to our previous studies, synergetic effect of cobalt complex and chrome salt is observed, with its maximum at high temperatures and for high current densities (industrial conditions). The Tafel slopes were found to be around 120 mV and exchange current densities in the range of 10⁻³ mA cm⁻² up to 10⁻² mA cm⁻². Results are presented to show the Tafel slopes, the exchange current densities, the apparent energy of activation and the apparent electrochemical surface of in situ formed Co–Cr catalyst. This study shows that catalytic performance of Co–Cr was achieved not only from the increase of the real surface area of electrodes, but also from the true catalytic effect.     

Relevance and costs of large scale underground hydrogen storage in France

The study analyzes the techno-economic feasibility and business case of large-scale hydrogen underground storage in France. Potential regions for locating the storage cavity were assessed, as well as the anticipated hydrogen demand and renewable energy developments. The business case of salt caverns storage facility has been assessed both in 2025 and 2050, looking at several demand sectors, including mobility (FCEVs), hydrogen-consuming industries and what is defined as “Power-to-Gas”. The hourly operation of the cavern has been modeled. The electricity supply is restricted to wind and grid electricity only.The mobility market is clearly the key driver, both in quantity and economic terms, with an easier to achieve target cost (€4/kgH2, ex-storage). High utilization rates of electrolysers are necessary to reach profitability. A need for massive storage begins for a renewable penetration rate of 50%. The hydrogen costs varies from €4.5/kg to €6.6/kg H2, and the underground mass storage cost remains always under 5% of the overall costs.     

The production of hydrogen fuel from renewable sources and its role in grid operations

Understanding the scale and nature of hydrogen's potential role in the development of low carbon energy systems requires an examination of the operation of the whole energy system, including heat, power, industrial and transport sectors, on an hour-by-hour basis. The Future Energy Scenario Assessment (FESA) software model used for this study is unique in providing a holistic, high resolution, functional analysis, which incorporates variations in supply resulting from weather-dependent renewable energy generators. The outputs of this model, arising from any given user-definable scenario, are year round supply and demand profiles that can be used to assess the market size and operational regime of energy technologies. FESA was used in this case to assess what - if anything - might be the role for hydrogen in a low carbon economy future for the UK.In this study, three UK energy supply pathways were considered, all of which reduce greenhouse gas emissions by 80% by 2050, and substantially reduce reliance on oil and gas while maintaining a stable electricity grid and meeting the energy needs of a modern economy. All use more nuclear power and renewable energy of all kinds than today's system. The first of these scenarios relies on substantial amounts of ‘clean coal’ in combination with intermittent renewable energy sources by year the 2050. The second uses twice as much intermittent renewable energy as the first and virtually no coal. The third uses 2.5 times as much nuclear power as the first and virtually no coal.All scenarios clearly indicate that the use of hydrogen in the transport sector is important in reducing distributed carbon emissions that cannot easily be mitigated by Carbon Capture and Storage (CCS). In the first scenario, this hydrogen derives mainly from steam reformation of fossil fuels (principally coal), whereas in the second and third scenarios, hydrogen is made mainly by electrolysis using variable surpluses of low-carbon electricity. Hydrogen thereby fulfils a double facetted role of Demand Side Management (DSM) for the electricity grid and the provision of a ‘clean’ fuel, predominantly for the transport sector. When each of the scenarios was examined without the use of hydrogen as a transport fuel, substantially larger amounts of primary energy were required in the form of imported coal.The FESA model also indicates that the challenge of grid balancing is not a valid reason for limiting the amount of intermittent renewable energy generated. Engineering limitations, economic viability, local environmental considerations and conflicting uses of land and sea may limit the amount of renewable energy available, but there is no practical limit to the conversion of this energy into whatever is required, be it electricity, heat, motive power or chemical feedstocks.