Device and method for the transport of energy

The present invention relates to the transport of energy. More specifically, the present invention relates to a system for the transport of energy and a method for the transport of energy. It is generally known in the art that energy carriers are transported from the place of extraction or production to the place of utilisation. For example, natural gas is extracted from the earth in several places in the world, subsequent to which it is usually transported to the consumers via pipes. Similarly, electricity is produced, for example, at power stations and subsequently transported to consumers via conductors. The manner of transport of the energy carriers is often determined by economical motives. During the transport and during the conversion from the one energy car- rier to the other (for example, the conversion at a power station from natural gas to electricity) energy losses occur. For the transport of energy carriers over very great distances, it is common practice in the art to elect to transport these energy carriers in liquid form in ships (oil tankers, methanol freight carriers and LPG-freight carriers) . For this type of transport natural gas is often converted into methanol, which is easier to transport in the liquid form. At the place of destination, the methanol can subsequently be converted into a different energy carrier. Gases, such as natural gas and hydrogen, are transported over hundreds and sometimes thousands of kilometres through pipelines. This requires pipelines that are expensive and susceptible to damage. As already known, this is the reason why natural gas, for example from Africa and South Amer- ica, is converted into methanol and subsequently transported by ship, for example, to Europe and North America.

In the prior art situation, the transport of electricity over such great distances involves considerable

losses. However, transport of electricity over shorter distances is very well possible and is very generally applied. With the declining supply of fossil fuel, such as natural gas and mineral oil and the negative effect of fuels based on these raw materials on the climate, the energy carriers will in future be of a significantly different nature. Solar energy will very probably become a large and important renewable energy source to be used. By means of photovoltaic conversion solar energy is converted into electricity. This conversion is most efficient in countries with a high sun incidence. Locations where the land cannot be used in other ways are preferred. Examples of these are desert areas such as the Sahara. The conversion of solar energy in the Sahara into electricity could, for example, serve to supply energy for Europe. However, the advantage of the large amounts of solar energy available for such conversions is cancelled out due to the losses occurring during the transport of electricity from the Sahara to Europe. Conversion of electricity into hydrogen and oxygen, with the hydrogen being transported in ships, involves high transport costs and energy losses. A possible alternative would be the transport of hydrogen to Europe through pipelines. However, this form of transport is just as expensive because of high conversion losses, transport losses and the costly infrastructure required for this. It is the object of the invention to provide an improved energy transport.

A particular object of the invention is to provide an improved system for transporting energy over greater distances. The term ^λ greater distances' refers to distances over which with the current commercially applied techniques uneconomical losses are incurred. A more specific object of the invention is to provide an improved system for transporting at least electricity over such greater distances.

A further object of the invention is to provide an improved system for the transport of a combination of electricity and another form of energy over great distances in a combined infrastructure.

An object of the invention in a further aspect of the invention is to provide an improved method for the transport of energy. A particular object of the invention is to provide an improved method as mentioned above with respect to the system of the invention.

In order to achieve at least one of the above- mentioned objectives, the invention provides a system for the transport of energy, comprising a conduit having an inlet end and an outlet end for the transport of hydrogen from the in- let end in the direction of the outlet end, wherein the inlet end comprises an inlet for the introduction of at least partly liquefied hydrogen into the conduit, and the outlet end comprises an outlet for discharging hydrogen from the conduit, and wherein for the transport of electricity the system further comprises a conductor, which is in thermal contact with the hydrogen in the conduit for the transport of hydrogen. This possibly, but not necessarily, provides the possibility of hydrogen that is conducted through a conduit is at least partly able to evaporate. Being in thermal con- tact with the hydrogen, the conductor will be able to take on the temperature of the hydrogen. According to a further preference, the system is therefore characterised in that the inlet end comprises an inlet for feeding substantially liquid hydrogen into the conduit. According to a further preferred embodiment, the invention is characterised in that the outlet end comprises an outlet for discharging from the conduit substantially liquid hydrogen. Especially when no or substantially no gaseous hydrogen is introduced into, or developed in, the conduit, the hydrogen discharged from the conduit can be simply prepared for further transport in liquid form.

It is further preferred for the outlet end to have an outlet for the discharge from the conduit of at least partly gaseous hydrogen. This may result in gaseous hydrogen conducted through or developed in the conduit forming a driving force ensuring that the hydrogen is transported through the conduit .

According to a further preference, the conductor is made of a material that at the temperature of the hydrogen, in particular the at least partly liquid hydrogen, in the conduit has superconductive properties. This will allow the electricity being conducted through the conductor to be transported substantially without losses. In this way, electricity can be transported over very great distances without incurring such losses as to make this transport unprofitable. Simultaneously hydrogen is transported through the conduit, which hydrogen can at the outlet end of the conduit be used in ways that are customary in the art, such as for example, the conversion into electricity by means of a fuel cell or oxidation of the hydrogen in vehicles.

The amount of hydrogen being transported through the conduit must be at least such as to allow the conductor to properly maintain the temperature at which it exhibits superconductive properties.

A person skilled in the art is quite capable of choosing those materials that have superconductive properties at an evaporation temperature of hydrogen. A person skilled in the art is also quite capable of determining which -amount of liquid hydrogen needs to be supplied to the conduit in order to maintain the temperature at or below the desired value over the entire length of the conduit. With the system according to the invention, the hydrogen is moved through the conduit so that the conductor for the transport of electricity, being in thermal contact with the hydrogen in the conduit, will acquire that same temperature. By fabricating the conductor of a material that has su- perconductive properties at or below the boiling temperature of liquid hydrogen, it is possible to transport electricity over great distances through this system, substantially without losses. At temperatures below room temperature, the resistance of electric conductors is considerably reduced com- pared with the resistance at room temperature, with the exception of the generally known NTCs. It is further preferred to supply the hydrogen to the conduit in substantially liquid form. The evaporation of only a portion of the liquid hydro-

gen will cause such a thrust that the hydrogen is transported to the outlet end of the conduit. In that case no additional pumps will be required for the transport of the hydrogen through the conduit. The inlet side must, however, be pro- vided with an adequate seal, or the liquid hydrogen must be supplied with sufficient pressure to prevent hydrogen being discharged at the inlet side. Within the context of the invention it is, however, equally possible to conduct the hydrogen through the conduit without evaporation, with the driving force being provided by one or several pumps. This affords the advantage that at the outlet side the hydrogen is suitable for further liquid transport.

As already mentioned, it is preferred for the temperature of the conductor for the transport of electricity to be a temperature of the hydrogen in the conduit. This provides an assurance regarding the properties of the conductor, especially when the same is made of a material, which is superconductive at that temperature.

In order to ensure thermal contact, it is preferred for the conductor to be introduced into the conduit. It is generally known in the art how an electrical conductor can be introduced into a conduit. Therefore this technique will not be further explained.

According to a further aspect, the invention relates to a method for the transport of energy, wherein the stated objectives are achieved when this method comprises the step of the transport of hydrogen through a conduit and the transport of electricity via a conductor for electricity, which is in thermal contact with the hydrogen. It is then especially preferred for the electrical conductor to be chosen from a material that has superconductive properties at or below an evaporation temperature of hydrogen. This will allow electricity to be transported over very great distances, practically without losses. A person skilled in the art is quite capable of choosing those materials, which exhibit superconductive properties at or below the evaporation temperature of hydrogen,

which at 1 atmosphere is 20 Kelvin. At other pressures the evaporation temperature will differ slightly from this value.

The invention is not limited to the variants described in the above-preferred embodiments. All the different components may be combined in any manner desired.

Hereinafter the invention will be further specified by way of a figure.

The single figure shows a conduit 1 for the transport of hydrogen. At the inlet end 2 liquid hydrogen is in- troduced into the conduit 1 in the direction of the arrow A, and transported to the outlet end 3 in the direction of the arrow B. At the inlet end 2, the hydrogen will preferably be supplied in substantially liquid form. Part of the supplied hydrogen may possibly evaporate in the conduit 1. It is pos- sible that a mixture of gaseous and liquid hydrogen, or that all the hydrogen is gaseous when it is extracted from the conduit 1 at the outlet end 3.

At a first position 5, an electrical conductor 4 is introduced into the conduit 1. At a second position 6, the conductor 4 exits the conduit 1. At least between the positions 5 and 6, the conductor 4 will take on the temperature of the hydrogen transported in the conduit 1.

The amount of hydrogen transported through the conduit 1 must at least be large enough that over the entire distance between the positions 5 and 6 hydrogen is present at least partly in liquid form. In particular at least between these positions a temperature must be maintained that is equal to, or lower than, the Tc of the electrical conductor (the temperature at which and below which the conductor has superconductive properties). A person skilled in the art is quite capable of working out the necessary amount of hydrogen, taking into account among other things, the heat carried from the environment to the conduit 1. Optionally, the conduit 1 may be divided into several successive sections, each having an inlet end and outlet end at the ends, so that any pressure difference at the ends of each section will be less than if the entire conduit 1 consisted of only one section. A

division into several sections helps to keep the temperature fluctuation within limits.

If the conduit 1 is extremely well insulated evaporation for the transport of the hydrogen through the conduit may, for example, be realised by a pressure drop at the outlet end 3 with respect to the inlet end 2. This pressure drop must be such that the evaporation temperature, which depends on the pressure of the hydrogen, is at least such that the material of which the conductor 4 is fabricated maintains the superconductive properties.

Another way of realising a partial evaporation of the hydrogen is by a directed supply of heat to the hydrogen, for example, via heating elements.

If desired, the conductor 4 may be inserted into the conduit 1 at a position other than position 5, for example, at position 7, and may exit at a position 8 instead of at the position 6. This is indicated with the broken line 4'.

The invention is not limited to the preferred embodiment described above by way of the single figure. The in- vention is limited by the appended claims only.

In addition, extra measures may be taken in the system shown in the figure if necessary, which however, for the sake of simplicity are not shown in the figure. For example, temperature sensors and pressure sensors may be provided at different positions in the conduit 1 to check the system's functioning. Also, valves and the like will be provided to control the supply of hydrogen to and the discharge of hydrogen from the conduit. Valves may also be provided in the conduit 1 between the positions 5 and 6 to control the pressure drop in the conduit.