GB2449620A - Using existing oil and gas drilling platforms for the conversion of renewable energy sources - Google Patents

Abstract

Existing oil and gas platforms 1 are used as a base for equipment adapted to convert renewable energy sources into usable power. Existing platforms are well established and engineered to face the heavy sea conditions they may encounter and provide a cost effective solution to the problem of providing a base for marine renewable energy converter systems. Converter systems including geothermal energy converters, ocean thermal energy converter systems 15, wave energy converters (21, Fig 2), sea current turbines (60, Fig 5), wind turbines (24 and 25, Fig 2), solar energy collectors (22 and 23, Fig 2) and salinity gradient converters may be installed on or alongside existing platforms during or after use in fossil fuel drilling. Re-use of the platforms also eliminates the cost of decommissioning platforms after fossil fuel drilling.

Description

1)ICSCR I I'll ON OIL ANI) GAS 1*1 iIlNC PLATFORMS AND OTI1EII MARINE

STR1J CU] RES REtISEI) F( )R RENEWABLE EN ERG V CON V ERTE1t SYSTEMS.

T his invention relates to the use of oil and gas drilling platforms and other marine structures reused for renewable energy converter systems.

Offshore or near shore platforms for renewable energy cofleclion and cOnvCrSiOfl have been proposed According to the present Invention, renewable energy (RE) collectiOfl and conversion systems can be incorporated on or moored alongsi(lC or around oil or gas drilling platforms, when the platforms are no longer used for their initial purposc, or whilst the platforms are in operation, using the drilling equipment on hoard, normally used to seek fossil fuels often at great depths below the sea bed, to seek warm aquifers or hot fissured rock beds, such that flow and return pipes can be installed, the warmed fluid being pumped to the surface, where It is used to evaporate a working fluid that drives a turbo generator, the said fluid being then taken to a cold seawater cooled condenser to be returned to its liquid slate ready to perform its next cycle, or to power underwater watcrtiglit pressurised turbo generators, a ftirtbcr cold water pipe running alongside the flow and return pipes delivering cold water from the depths to an ocean thermal energy converter (OTEC) system, the said platform being surrounded by arrays of separately moored wave energy converters producing electricity from turbines activated by wave motion, Interrupted to allow protected navigation to and from the rig, sea current turbines fitted to the underside, and wind turbines above far enough away from the rig to allow safe operation of service helicopters, the upper surfaces being fitted with solar energy collectors, other marine energy sources, such as salinity gradicnts, being included where possible, the electricity produced by each RE conversion system either being cabled to shore, or converted to hydrogen stored and tankered or piped to land, the diverse RE systems being more readily instalJed on the said platform after its fossil fuel drilling use is over, when It can either be lefi in place as the core of an RE structure, or be transported to areas of less severe sea conditions where its useful life can be much extended either in its existing condition or after some occessary overhauling is carried out, far less expensive than dismantling or new construction, ready for an ecologically sound "second life", other disused platforms, barges, ships or tankers being used In the same way.

A specific embodiment of the invention will now he described by way of example with reference 10 the accompanying drawings in which:-Figure 1 shows a perspective top view of a working oil and gas dnllrng rig platform 10 which has been added an Independently floated or structured smaller platform having its own drilling tower with its geothermal drilling pipe and Oi'FC cold water pipe, and associated turbogenerator plant rooms, laboratories and living quarters.

Figure 2 shows the basic assembly referred to in Figure 1 to which have been added a number of complementary RE converters4 FIgure 3 shows an oil/gus rig reused as an ocean thermal energy converter (OlEC) carrier, with all its necessary equipment.

Figure 4 shows an oil/gus rig reused as a geothermal energy converter system carrier, with all its necessary equipment; Figure 5 shows a perspective view of an assembly of reused marine structures forming a RE complex, with collateral functions.

liigure 6 shows a plan view of the same complex.

Referring to the drawing I, an oil/gas offshore drilling rig platform,l, is supported by 4 concrete or steel columns,4, braced between each other, either providing flotation for the whole assembly, or designed to sit on the sea bed. The platform is provided with drilling towers of varying heights, 2 and 3, and drill pipes for gas,?, or oil, 8, and, when offshore, has all necessary equipment on board, and is serviced by ships for conveying heavy equipment hoisted by cranes, 5, and reached by helicopters using the helipad.6, provldcd Every square meter of a working platform is fully used An additional platform,1O, for some marine RE applications, called the RE platform, having its own floating or supporting structure,1I, is brought alongside the edge furtherest away from the helipad of the main platform,, or positioned close to the main platform, with a linking bridge, having on hoard its own drilling towcr,12, and its own drill pipes, 13 and 14, With the oil rig platform, it thus fonns a single platform such that the specialist staff, equipment and know how of the oil rig personnel can assist in its implementation, forming an RE addition to the original rig.

This RIC rig would drill for geothermal energy with one pipe, 13, under the sea bed to seek warm aquifers or fissured hot rock beds, returning hot water in an iftsulate(l pipc,14, the hot water used to evaporate a fluid used to power a turbogenerator, the vapour being condensed by coolth front seawater.

In parallel, for OTEC power, a pipej7, stabilised by the lower sea I)Cd, pumps coW water from she depths which acts as the condenser to liquefy a working fluid to be evaporated by the high surface temperatures of warm oceans, or by high air temperatures where insufficient warmth is derived from the sea surface, alternatively, an "open" 011CC system being used in which seawater, evaporated under partial vacuum, acts as the working fluid, which, when condensed, provides significant quantities of desalinated distilled water.

A plant room, 15, is provided to house the turbogenetrators for the geothermal and OTEC energy converters, the electricity produced either used for the heavy requirements of the combined rigs themselves, the rest being cabled to land, or transformed by hydrolysis or other processes to hydrogen tern porarily stored in tanks below the RE rigs, or in moored drogues alongside and taken to land by tankers or pipelines.

The standard rig, adapted to geothermal and OTEC needs either on Its own adapted platform, or by the addition of the RE rig will prod net the combined rigs' energy demands, a synergy between fossil fuel extraction and RE conversion.

This combination platform can stand on Its own.

Referring to Figure 2, it can also act as the core for further RE conversion systems. The initial platform I with its RE geothermal and O'FEC drilling facilities, 10, has a further platform, 19, or sets of platforms, 20, linked to It with supplementary RE converter systems.

In a floating near or offshore situation, a wave energy converter (WEC) is positioned facing prevailing strong seas, and so protects the combined rigs from these, so relieving stresses they are put to, and increasing their salety and lifespan. Many WECs can be used to this effect, the one shown here, 21, would be a concrete or steel structure stepping up from the ea front, of a section of boxed or honeycombed construction opened at Its base to provide tuned oscillating water columns of sea water of varying heights compressing air to drive turbines, the top of each step presenting a surface inclined towards the wave front so that high seas break over these inclined surfaces to reach, at the top of each step, a channel recovering this water, powering further water turbines and increasing the efficiency of the WEC as a breakwater, the top channel designed to protect the rigs from high freak waves.

i'he flotation water line, 9, is shown running along the lower third of the W EC.

On lop of the WEC Is a framc,22, carrying an array of solar collectors, 23, lacing south, these being photovoltaic, photothermal, dispersed concentrating or mirror focussing depending on the overall energy systems adopted.

At each side of the WEC unit are two flotation buoys, 26, supporting two aerogenerators, 24, held on masts, 25, these being optionally hydraulically engineered to be lowered If the swept area of one aerogencrator is in the "shadow" of the other.

When the whole assembly is in deep waters with known currenis, the masts are prolonged underwater where sea current generators,27, are fitted to increase the overall energy production of the combined platforms.

in a further embodiment of the invention, , when the life of the oil drilling rig is over, its structure is still often In good condition, and if placed in less severe climatic conditions, could serve us the core element of an offshore RE complex.

Referring to Figure 3, in Its simplest reuse, the adapted platform, 31, is floated to tropical areas where OTEC can be operational, needing no drilling capacity or towers for geothermal energy, relying on a cold water pipe, 32, stretchIng down to cold waters pumped up from the deep to act as the condenser, 33, of turbogenerator fluid evaporated by an evaporator, 34, taking energy from surrounding hot sea surface waters, 35, the said working fluid in some configurations being pumped down to deep sea condensers, 36. The platform is used to house the turbogeneralors and associated electrical transformation equIpment, 37. Electricity can be cabled to land, or hydrolysis equipment tan be mounted on board with hydrogen short term storage tanks. 38. 1'he helipad is kept for transport and ship berthing, 39 and craning are Included. The top surface of platform buildings housing ground level facilities needed by the platform and staff facilities Is free to be used for a number of other RE applications, typically solar panels, 40 to provide some of the platform's energy needs.

Referring to Figure 4, in a reuse for colder seas where OTEC is not feasible, the oil rigs can be taken to different sites looking for geothermal energy.. In some cases, drilling wilt be needed, the drilling towers left in place on the adapted platform, 41, the pipes and bits, 42, adapted to seek out thermal energy sources, Insulated flow and return pipes being subsequently put in place to extract the heat to power an on board lurbogenerator,43, surface sea water being the coolant, or a pressurised turbogenerator lowered down to the sea bed using the cold water from greater depths to increase the

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temperature tlifferential between the hot source and its coolant, increasing the overall generation efficiency, the generated electricity cabled lip to the platform. The platform shown iii Figure 4 has the capacity to move and seek out other nearhy geothermal energy sources, their connect in us taken to simple floating platforms for power generation, storage and distribution, not requiring (lie drilling capacity of the original geothermal drilling platform. Where high temperature underwater energy sources are availal)le without drilling, us in the case of thermal underwater geysers, or along a geological flaw where hot lava, sometimes visible, conies to the sea tied producing very high temperatures, the surrounding waler kept from boiling by the high water pressure, the heat can either be made to rise by therm osyphon in an insulated pipe, replacing the cold water pipe, to be used to power on board turbogenerators, or can be used in lowered pressurised turbogenerators as described.

Referring to Figures 5 and 6, in a further embodiment of the invention, as shown, by way of an example, a number of diverse floating disused marine structures are brought together to he reused to form a "complex" of platforms, 50, designed to harvest a variety of energy sources available at sea. A group of 6 disused oil tankers moored together side by side forms a large platform, 51, the top surface of which is used to receive a field of mirrorised heliostats, 52, focussing onto a raised focal furnace, constituting a "power tower" solar power station. Below the mirrors, and shaded by them from high insolation, is a layer of greenhouses, 53, used for demonstration hydroponic plant growth, evaporatively cooled. The mirrors can lay flat in bad weather and form a shell protecting themselves as well as the greenhouses below them. The upper side of other tankers include solar collectors, 68, above greenhouses or other facilities, 69.

Alongside this main platform, Its protective walls formed by a further three tankers, is a near square harbour of protected waters, 54, the "complex" constituting roughly a double square which is orientated so that one long side faces the prevailing wave direction, and is fitted with a wave energy converter system either moored alongside the tankers or being formed as an integral part of the tankers themselves, 55, thereby Increasing the RE conversion of the platform, and reducing the sea movements of the "complex", and so the stresses of its Joining pieces, whether rigid or flexible, calming the harbour waters, and allowing a protected entry to the harbour entrance, 56, on the leeside of the complex, such that boats can enter the harbour safely in heavy seas. The said harbour can be used as an experimental "solar pond" power generator, either collecting thermal energy In the calmed waters, or biomass energy destined to an anaerobic gasification plant. Below the complex, fish farming pens can he installed.

The "complex" is sufficiently large to include a significant wind farm, with aerogefleraton; 59, at each corner of both near squareSt a total o 6 large aerOgeflertors each (IflC either held on poles fixed into the structure of the tanker, or floated with its own notation buoy next to or away from (be "complex", optionally mounted on hydraulic poles to give then' better performance in variable direction wind conditions.

Sea current energy converters,60, are mounted directly below the "complex", In rbogcnerators either attached directly to the hulls if the currents are surface currents and relatively constant in directioit, or moored separately at the required depth, able to rotate to intercept any changes in current direction.

Additionally, a reused oil rig, 31 is located over a geological heal source to recover geothermal energy from the sea bed.

Another reused oil rig, 41, houses an OTEC Plant where high sea lemperatures and great depths allow its installation, or an air to water heat exchanger, mounted on one of the tanker's bulls such that the'n"d energy from surrounding air acts as the evaporator, and sea water from medium depths acts as the condenser for an on board turbogenerator.

The major part of electricity generation is hydrolysed to hydrogen gas, to fte(l a clean new hydrogen economy for transport, industry, heating and cooling, for all public and domestic energy uses.

A tanker equipped to store hydrogen gas is moored alongside a reused tanker, 62, in the lea of high seas, transferring its content when full to shuttling tankers, or itself taking the hydrogen to shore whilst another takes its place. Other tankers, 63, serve the two attached reused oil drilling platforms.

The port entry would give general shipping access to the complex.

Since the vast internal volume of the tankers is not used by RK applications, it is suggested that the aligned "afts" of the tankers are fitted with vehicular access at high levels, 64, served by the harbour edge so that, with the provision of intenial metal ram for general storage and wareho and floors, their vast volume can be used compatible uses, helpiiug to using, car and boat parking, and any other "complex". to the financial viability of the overall If boat berthing and storage is foreseen, visitor facilities will he needed, A helipad, able to handle large helicopters, will complement the harbour.

Moorings for large ships, 66, to the lee side will be foreseen.

l'he "complex" is large enough to house a visitor centre, with hotels, shopping malls and restaurants built into the overall structure, the RE demonstration, with research centres, conference facilities anti guided tours adding interest for day or longer term visitors.

Production of electricity transformed Into hydrogen from RE sources is the principal goal of the "complex", a step towards the necessary hydrogen Economy of the liii tire.

Claims (9)

1. CLAiMS Renewable energy (1(E) collection and conversion systems can be

   incorporated on or moored alongside or around oil or gas drilling platforms, when the platforms are no longer used for their initial purpose, or whilst the platforms are in operation, using the drilling equipment on board, normally used to seek fossil fuels often at great depths below the sen bed, to seek warm aquifers or hot fissured rock beds, such that flow and return pipes can be installed, the warmed fluid being pumped to the surface, where It is used to evaporate a working fluid that drives a turbo generator, the said fluid being (lien taken to a cold seawater cooled condenser to be returned to its liquid state ready to perform Its next cycle, or to power underwater watertight pressurised turbo generators, a further cold water pipe running alongside the flow and return pipes delivering cold waler from the depths to an ocean thermal energy converter (OTEC) system, the said platform being surrounded by arrays of separately moored wave energy converters producing electricity from turbines activated by wave motion, interrupted 10 allow protected navigation to and from the rig, sea current turbines fitted to the underside, and wind turbines above far enough away from the rig to allow sale operation of service helicopters, the upper surfaces being fitted with solar energy collectors, other marine energy sources, such as salinity gradients, being included where possible, the electricity produced by each RK conversion system either being cabled to shore, or converted to hydrogen stored and tankered or piped to land, the diverse RE systems being more readily installed on the said platform after its fossil fuel drilling use is over, when it can either be left in place as the core of an RE structure, or be transported to areas of less severe sea conditions where its useful lift can be much extended either in Its existing condition or after some necessary overhauling Is carried out, far less expensive than dismantling or new construction, ready for an ecologically sound "second life", other disused platforms, barges, ships or tankers being used in the same way.
2. 2 Other marine structures, as claimed in Claim 1, such as tankers and other vessels, reused to provide platforms for renewable energy converter systems.
3. 3 Reused tankers or other marine structures, as claimed in Claim 2, linked together, forming a platform for a "power tower" solar collector field, the collectors being mirror heliostats focussing onto a raised central furnace, the collectors mounted above greenhouses or other facilities structures which they protect from the sun, and, being able to take up a near horizontal position, form a skin over these structures protecting them and Iliemselves from foul weather conditions.
4. 4 Reused tankers or other marine structures, used to form the structure for wave energy converters, either integrally fitted along the tankers edge, or a series of oscillating water columns linked to an overspill channel system on a sloping surface above these, driving turbines, backing onto the reused marine structures.
5. S Reused marine structures, as claimed in Claim 2, forming the support for wind aerogenerators and sea current energy converters.
6. 6 A reused oil/gas drilling rig used for an Ocean Thermal Energy Conversion (OTEC) system, as claimed in Claim 1, able to carry the heavy heat exchangers and turbo generators, as well as the large diameter Cold Water Pipe, electrical transformation equipment, hydrolysis equipment, hydrogen short lenn storage, staff quarters, ship berthing and * helipad, necessary for its operation.
7. 7 A reused oil/gas drilling rig, as claimed In Claim 1, used for geothermal prospecting, using its drilling capacity to seek hot aquifers or hot fissured rock beds to bring the heat to the surface to power turbo generators producing electricity either cabled to shore or hydrolysed to produce hydrogen gas, with all necessary equipment on board. in a variant, the turbo generator can be lowered by cranes to the sea bed, the heat source being piped to It, and coolant waters being around it.
8. 8 An assembly of reused marine structures such as they form the structure tor RE converters, hut can also be used for other purposes, providing protected waters lii their leeside for marinas,

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   harhours, container ports, and other uses, Including storage or car parking and boat storage on a vast scale provided by making the inside OISUCI marine structures accessible. The varied RE converters produce electricity which is either cabled to shore, or converted by hydrolysis to hydrogen gas, which can he taken to nearby or faraway destinations by tanker or pipeline, providing a signilicat1l source of hydrogen, the clean energy of the future.
9. 9 Moored floating or shore based reused marine structures substantially as described herein with reicrence to figures 1-6 of the accompanying drawings