A quantitative assessment of the hydrogen storage capacity of the UK continental shelf

Increased penetration of renewable energy sources and decarbonisation of the UK's gas supply will require large-scale energy storage. Using hydrogen as an energy storage vector, we estimate that 150 TWh of seasonal storage is required to replace seasonal variations in natural gas production. Large-scale storage is best suited to porous rock reservoirs. We present a method to quantify the hydrogen storage capacity of gas fields and saline aquifers using data previously used to assess CO₂ storage potential. We calculate a P50 value of 6900 TWh of working gas capacity in gas fields and 2200 TWh in saline aquifers on the UK continental shelf, assuming a cushion gas requirement of 50%. Sensitivity analysis reveals low temperature storage sites with sealing rocks that can withstand high pressures are ideal sites. Gas fields in the Southern North Sea could utilise existing infrastructure and large offshore wind developments to develop large-scale offshore hydrogen production.     

Job retention in the British offshore sector through greening of the North Sea energy industry

For the case of the UK there are currently three ways of obtaining energy from sea areas, namely from wind, tides and waves. A methodology was developed to determine the future size of the offshore renewable industry based on the concept of employment factor, or the number of people required to maintain each unit of electricity production. An assessment was made of the decline in the number of people employed in oil related jobs in the North Sea and the gap that this could create in the UK's economy unless this pool of offshore expertise could find an alternative employment in the renewable sector. The paper will also investigate the effect of gradually transforming the UK's oil and gas sector into offshore renewables. If this was to happen by 2050 the UK offshore renewable industry could produce between 127 and 146 TWh of electricity, equivalent to around 57–66% of the current energy consumption in the country.     

Interconnector capacity allocation in offshore grids with variable wind generation

Different capacity allocation regimes have a strong impact on the economics of offshore wind farms and on interconnectors in offshore grids. Integrating offshore generation in offshore grids is currently a subject of discussion for different regions, e.g. the North Sea. A novel question is how the interconnector capacity should be allocated for wind generation and for international power trading. The main difficulty arises from the stochastic nature of wind generation: in a case with radial connections to the national coast, the wind park owner has the possibility of aggregating the offshore wind park with onshore installations to reduce balancing demand. This is not necessarily the case if the interconnector capacity is sold through implicit or explicit auctions. Different design options are discussed and quantified for a number of examples based on Danish, Dutch, German and Norwegian power markets. It is concluded that treating offshore generation as a single price zone within the interconnector reduces the wind operator's ability to pool it with other generation. Furthermore, a single offshore price zone between two markets will always receive the lower spot market price of the neighbouring zones, although its generation flows only to the high‐price market. Granting the high‐price market income for wind generation as the opposite design option reduces congestion rents. Otherwise, compensation measures through support schemes or different balancing responsibilities may be discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Offshore wind energy prospects

In last two years offshore wind energy is becoming a focal point of national and non national organizations particularly after the limitations of fossil fuel consumption, adopted by many developed countries after Kyoto conference at the end of 1997 on global climate change. North Europe is particularly interested in offshore for the limited land areas still available, due to the intensive use of its territory and its today high wind capacity. Really the total wind capacity in Europe could increase from the 1997 value of 4450 MW up to 40 000 MW within 2010, according the White Paper 1997 of the European Commission; a significant percentage (25%) could be sited offshore up to 10 000 MW, because of close saturation of the land sites at that time. World wind capacity could increase from the 1997 value of 7200 MW up to 60 000 MW within 2010 with a good percentage (20%) offshore 12 000 MW. In last seven years wind capacity is shallow waters of coastal areas has reached 34 MW. Five wind farms are functioning in the internal seas of Netherlands, Denmark, Sweden; however such siting is mostly to be considered as semi-offshore condition. Wind farms in real offshore sites, open seas with waves and water depth over 10 m, are now proposed in North Sea at 10–20 km off the coasts of Netherland, Denmark using large size wind turbine (1–2 MW). In 1997 an offshore proposal was supported in Netherland by Greenpeace after the OWEMES '97 seminar, held in Italy on offshore wind in the spring 1997. A review is presented in the paper of the European offshore wind programs with trends in technology, economics and siting effects.     

Offshore renewable energy exploitation strategies in remote areas by power-to-gas and power-to-liquid conversion

Chemical storage of electric energy is recognised as a potential solution to improve the penetration of renewable energy. The coupling of renewable power production with offshore oil & gas exploitation by converting electricity into synthetic fuels represents an opportunity to valorize renewables in remote areas in an energy transition panorama. The present study aims at a comparison of alternative power-to-gas and power-to-liquid strategies for the conversion of offshore wind power into different chemical energy vectors (hydrogen, synthetic natural gas and methanol), taking advantage of conventional offshore oil & gas infrastructures for energy conversion and synthetic fuel transportation. A set of technical, economic, environmental and profitability performance indicators was defined to allow the comparison. A case study in the North Sea was analysed. The results showed that electrolyzers capacity and offshore-onshore distance play an important role on economic indicators. Sensitivity analysis was carried out to test the robustness of the results.     

Exploring the potential of wind energy for a coastal state

Adequate recognition of the wind energy potential of coastal states may have far-reaching effects on the development of the energy systems of these countries. This study evaluates wind energy resources in Taiwan with the aid of a geographic information system (GIS), which allows local potentials and restrictions such as climate conditions, land uses, and ecological environments to be considered. The findings unveiled in this study suggest a significant role for offshore wind energy resources, which may constitute between 94% and 98% of overall wind resources in Taiwan. Total power yield from wind energy could reach between 150 and 165 TWh, which would have, respectively, accounted for between 62% and 68% of Taiwan's total power generation of 243 TWh in 2007. Based on the Taiwan's current emission factor of electricity, wind energy has the potential to reduce CO₂ emissions by between 94 and 102 million ton per year in Taiwan, which is, respectively, equivalent to 28% and 31% of the national net equivalent CO₂ emissions released in 2002. However, the challenge of managing the variability of wind power has to be addressed before the considerable contribution of wind energy to domestic energy supply and CO₂ reduction can be realized.     

A framework to determine optimal offshore grid structures for wind power integration and power exchange

This paper presents a framework to find optimal offshore grid expansions using a transportation model of the power grid. The method extends the standard mixed‐integer linear programming approach to the solution of the transmission expansion planning problem to account for fluctuations in wind power generation and load; this makes the method especially suited to identify optimal transnational offshore high‐voltage direct current grid structures for the integration of large amounts of offshore wind power. The applicability of the method is demonstrated by a case study of the North Sea region. Copyright © 2011 John Wiley & Sons, Ltd.     

Key challenges to expanding renewable energy

The key advantage of renewables is that they are free of direct pollution and carbon emissions. Given concern over global warming caused by carbon emissions, there are substantial policy efforts to increase renewable penetrations. The purpose of this paper is to outline and evaluate the challenges presented by increasing penetrations of renewable electricity generation. These generation sources primarily include solar and wind which are growing rapidly and are new enough to the grid that the impact of high penetrations is not fully understood. The intrinsic nature of solar and wind power is very likely to present greater system challenges than “conventional” sources. Within limits, those challenges can be overcome, but at a cost. Later sections of the paper will draw on a variety of sources to identify a range of such costs, at least as they are foreseen by researchers helping prepare ambitious plans for grids to obtain high shares (30–50%) of their megawatt hours from primarily solar and wind generation. Energy poverty issues are outlined and related to renewable costs issues.     

Cost-effectiveness of renewable electricity policies

We analyze policies to promote renewable sources of electricity. A portfolio standard (RPS) raises electricity prices and primarily reduces gas-fired generation. A knee of the cost curve exists between 15% and 20% goals for 2020 in our central case, and higher natural gas prices lower the cost of greater reliance on renewables. A renewable energy production tax credit lowers electricity price at the expense of taxpayers, which limits its effectiveness in reducing carbon emissions, and it is less cost-effective at increasing renewables than a portfolio standard. Neither policy is as cost-effective as a cap-and-trade policy for achieving carbon emission reductions.     

IEEE Power Engineering Review

France appears to have the second largest wind energy potential in Europe, after the United Kingdom. According to certain estimates the potential annual production is evaluated at 70 TWh on the land and more than 90 TWh for offshore sites located in an area along the coast, with a maximum width of 10 km and where the sea depth is less than 10 m. This potential production of more than 160 TWh represents approximately 33% of the present electricity generation in France. However, the wind energy potential that will actually be exploitable will be noticeably lower. This paper describes the EOLE 2005 Program, a French national program for the promotion of wind power, launched in February 1996. The targets and incentive measures for wind power development are discussed. The grid connection of wind farms and offshore wind energy are also discussed.     

High resolution modelling of the on‐shore technical wind energy potential in Spain

The potential of on‐shore wind energy in Spain is assessed using a methodology based on a detailed characterization of the wind resource. To obtain such a characterization, high‐resolution simulations of the weather in Spain during 1 year are performed, and the wind statistics thus gathered are used to estimate the electricity‐generation potential. The study reports also the evolution with the installed power of the capacity factor, a parameter closely related to the cost of the generated energy, as well as the occupied land, which bears environmental and social acceptance implications. A parametric study is performed to assess the uncertainties in the study associated to the choice of the characteristic wind‐turbine farm used; and comparisons are provided with other similar studies. The study indicates that the overall technical potential is approximately 1100 TWh/y; and that about 70 GW of installed wind power could operate with capacity factors in excess of 24%, resulting in an annual electricity generation of approximately 190 TWh/y, or 60% of the electricity consumption in 2008. Copyright © 2010 John Wiley & Sons, Ltd.     

Pre-feasibility study of wind power generation in holyrood, newfoundland

The largest commercial thermal generating plant in Newfoundland is in Holyrood, Conception Bay. It has a generating capacity of 500 MW of electricity. During peak generation (winter months), the plant runs at near capacity with generation reaching as high as 500 MW. In addition to thermal generation about 900 MW is supplied to the grid by a number of hydro plants. This paper presents a pre-feasibility study of 25% of thermal power generation using wind turbines in the Holyrood area. Purpose of supplementing power generation from the thermal plant is to reduce emissions and fuel costs. Simulation results indicate that 16 Enercon's E-66, 2 MW wind turbines if installed near the site will provide a 25% renewable fraction. Supplementing 25% of the generation at Holyrood with wind power will reduce the cost of energy by CA$0.013/kWh. It will also reduce carbon emissions by almost 200,000 tons/year. This study indicates that a wind farm project at the Holyrood thermal generation station site is feasible.     

Wind energy (30%) in the Spanish power mix—technically feasible and economically reasonable

The installed wind power capacity in Spain has grown strongly in recent years. In 2007, wind parks supplied already 10% of the 260 TWh generated electricity. Along that year the installed wind capacity grew by 33.2%, from 11.63 GW in January to 15.5 GW in December. Wind is nowadays the primer renewable power source in Spain, while the public perception of renewables in general is very positive. The issue of the integration of wind power as a fluctuating source into the power grid is gaining priority.     

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.     

Valuing the manufacturing externalities of wind energy: assessing the environmental profit and loss of wind turbines in Northern Europe

This study draws from a concept from green accounting, lifecycle assessment, and industrial ecology known as 'environmental profit and loss” (EP&L) to determine the extent of externalities across the manufacturing lifecycle of wind energy. So far, no EP&Ls have involved energy companies and none have involved wind energy or wind turbines. We perform an EP&L for three types of wind turbines sited and built in Northern Europe (Denmark and Norway) by a major manufacturer: a 3.2 MW onshore turbine with a mixed concrete steel foundation, a 3.0 MW offshore turbine with a steel foundation, and a 3.0 MW offshore turbine with a concrete foundation. For each of these three turbine types, we identify and monetize externalities related to carbon dioxide emissions, air pollution, and waste. We find that total environmental losses range from €1.1 million for the offshore turbine with concrete foundation to €740,000 for onshore turbines and about €500,000 for an offshore turbine with steel foundation—equivalent to almost one‐fifth of construction cost in some instances. We conclude that carbon dioxide emissions dominate the amount of environmental damages and that turbines need to work for 2.5 to 5.5 years to payback their carbon debts. Even though turbines are installed in Europe, China and South Korea accounted for about 80% of damages across each type of turbine. Lastly, two components, foundations and towers, account for about 90% of all damages. We conclude with six implications for wind energy analysts, suppliers, manufacturers, and planners. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimizing hybrid offshore wind farms for cost-competitive hydrogen production in Germany

Nearly 96% of the world's current hydrogen production comes from fossil-fuel-based sources, contributing to global greenhouse gas emissions. Hydrogen is often discussed as a critical lever in decarbonizing future power systems. Producing hydrogen using unsold offshore wind electricity may offer a low-carbon production pathway and emerging business model. This study investigates whether participating in an ancillary service market is cost competitive for offshore wind-based hydrogen production. It also determines the optimal size of a hydrogen electrolyser relative to an offshore wind farm. Two flexibility strategies for offshore wind farms are developed in this study: an optimal bidding strategy into ancillary service markets for offshore wind farms that build hydrogen production facilities and optimal sizing of Power-to-Hydrogen (PtH) facilities at wind farms. Using empirical European power market and wind generation data, the study finds that offshore-wind based hydrogen must participate in ancillary service markets to generate net positive revenues at current levels of wind generation to become cost competitive in Germany. The estimated carbon abatement cost of “green” hydrogen ranges between 187 EUR/tonCO₂e and 265 EUR/tonCO₂e. Allowing hydrogen producers to receive similar subsidies as offshore wind farms that produce only electricity could facilitate further cost reduction. Utilizing excess and intermittent offshore wind highlights one possible pathway that could achieve increasing returns on greenhouse gas emission reductions due to technological learning in hydrogen production, even under conditions where low power prices make offshore wind less competitive in the European electricity market.     

Offshore wind development in China and its future with the existing renewable policy

Based on independent studies, this paper focuses on the significant discrepancy of 15 GW between the installed onshore wind generation capacity and what has been actually connected to the power network to reveal the challenges in meeting the Chinese renewable energy target. The recent accidents in Chinese North-Western transmission network (in February–April, 2011) demonstrated the urgent need for a fundamental review of the Chinese renewable energy policy. Offshore wind has been identified as the most feasible alternative to onshore wind to help deliver electricity to Eastern China during the summer peak time. By investigating and summarizing first hand experiences of participation in the Chinese renewable market, the authors provide the economic figures of the first cohort of Chinese offshore wind schemes. Large state owned enterprises (SOE) are dominating the offshore wind development, repeating their previous practices on the land. While this paper acknowledges the critical role of offshore wind generation in meeting Chinese renewable energy targets, it envisages an installed offshore capacity of approximately 2000 MW by 2015, much less than the 10000 MW governmental estimation, which can be attributed to the lack of detailed energy policy, network constraints, offshore wind installation difficulties and quality issues in the manufacture of turbines.     

Analysis of impacts of wind integration in the Tamil Nadu grid

As the share of wind in power systems increases, it is important to assess the impact on the grid. This paper combines analysis of load and generation characteristics, generation adequacy and base and peak load variations to assess the future role of wind generation. A simulation of Tamil Nadu in India, with a high penetration of wind power (27% by installed capacity), shows a capacity credit of 22% of the installed wind capacity. For seasonal wind regimes like India, neither the capacity factor, nor the capacity credit reflects the monthly variation in the wind generation. A new approach based on the annual load duration curve has been proposed for generation expansion planning with higher penetration of wind. The potential savings in base and peak capacity required with increasing wind power have been quantified. A future scenario for Tamil Nadu for 2021 has been illustrated. It was found that 5500 MW of wind power can save 3200 MU of peak energy required or an average peak capacity of 2400 and 1100 MW of base capacity. This analysis would be useful to assess the future impacts of increasing wind capacity in grids.     

Impact of hydrogen energy storage on California electric power system: Towards 100% renewable electricity

Decarbonization of the power sector is a key step towards greenhouse gas emissions reduction. Due to the intermittent nature of major renewable sources like wind and solar, storage technologies will be critical in the future power grid to accommodate fluctuating generation. The storage systems will need to decouple supply and demand by shifting electrical energy on many different time scales (hourly, daily, and seasonally). Power-to-Gas can contribute on all of these time scales by producing hydrogen via electrolysis during times of excess electrical generation, and generating power with high-efficiency systems like fuel cells when wind and solar are not sufficiently available. Despite lower immediate round-trip efficiency compared to most battery storage systems, the combination of devices used in Power-to-Gas allows independent scaling of power and energy capacities to enable massive and long duration storage. This study develops and applies a model to simulate the power system balance at very high penetration of renewables. Novelty of the study is the assessment of hydrogen as the primary storage means for balancing energy supply and demand on a large scale: the California power system is analyzed to estimate the needs for electrolyzer and fuel cell systems in 100% renewable scenarios driven by large additions of wind and solar capacities. Results show that the transition requires a massive increase in both generation and storage installations, e.g., a combination of 94 GW of solar PV, 40 GW of wind, and 77 GW of electrolysis systems. A mix of generation technologies appears to reduce the total required capacities with respect to wind-dominated or solar-dominated cases. Hydrogen storage capacity needs are also evaluated and possible alternatives are discussed, including a comparison with battery storage systems.     

Optimal asset allocation of wind energy units in conjunction with demand response for a large‐scale electric grid

Demand response is considered to be a realistic and comparatively inexpensive solution aimed at increasing the penetration of renewable generations into the bulk electricity systems. The work in this paper highlights the demand response in conjunction with the optimal capacity of installed wind energy resources allocation. Authors proposed a total annual system cost model to minimize the cost of allocating wind power generating assets. This model contains capacity expansion, production, uncertainty, wind variability, emissions, and elasticity in demand to find out cost per hour to deliver electricity. A large‐scale electric grid (25 GW) is used to apply this model. Authors discovered that demand response based on interhourly system is not as much helpful as demand response grounded on intrahourly system. According to results, 32% wind generation share will provide the least cost. It is also worth noting that optimal amount of wind generation is much sensitive to installation cost as well as carbon tax.