Patent Description:
Renewable energy produced by a renewable energy generating system, such as a windfarm comprising one or more wind turbines, solar generators, and so on, is called green energy. Based on the produced energy over the year, green energy certificates, also referred to as Guarantees of Origin (GoO) are issued to customers by a trading company, called utility. The green energy certificates are issued for produced energy for a month generated in an earlier month. Currently, a certificate has a size equal to <NUM> MWh of renewable energy. A disadvantage of the certificate system as of today is that it is possible to label energy produced from non-renewable energy sources (sometimes called as grey energy) as green energy by simply buying green energy certificates of an equal amount. As it is not possible to trace back the origin to a specific renewable energy generating system, the proof that a consumer is fully supplied by green energy is thus only possible on paper today.

<CIT> proposes a system for the cryptographically-secure, autonomous control of devices comprising, connected to or remotely operating devices in an electrically powered network and the transaction of the benefits, costs or value created by or transacted through the devices in this electrically powered network. In particular, it is proposed that the controller is configured to control the computation processes and heat recovery processes of multiple heat recovery sites.

It is an object of the present invention to provide a method that enables a more reliable method for issuing green energy certificates which are proof against manipulating. It is a further object to provide an apparatus which is adapted to carry out a method according to the invention.

These objects are solved by a method according to claim <NUM>, an apparatus according to claim <NUM>, a renewable energy generating system according to claim <NUM> and a computer program product according to claim <NUM>.

The invention provides a method for computer-implemented monitoring of energy production of a renewable energy generating system. The renewable energy generating system comprises one or a group of more renewable energy generators. A renewable energy generator may be, for example, a wind turbine or a photovoltaic system. In case of a plurality of wind turbines, the renewable energy generating system may be a windfarm. In case of a plurality of photovoltaic systems, the renewable energy generating system may be a photovoltaic plant.

During the operating of the renewable energy generating system for a predetermined period of time, the following steps are performed one after the other:
As a first step, a produced energy amount of the renewable energy generating system in the predetermined period of time is determined by a first energy meter. The first energy meter may be any suitable measurement equipment or device, which can be, for example, provided by the manufacturer of the renewable energy generator.

As a next step, the produced energy amount of the renewable energy generating system in the predetermined period of time is verified by an independent instance, wherein the latter is a second energy meter being different from the first meter. Verifying the produced energy amount of the renewable energy generating system comprises doublechecking whether the determined produced energy amount of the first energy meter is correct by comparing the produced energies determined from the first and the second energy meters.

As a further step, an energy certificate for the renewable energy generating system for the predetermined period of time is issued by a computing unit. The energy certificate at least comprises a time stamp indicating the predetermined period of time, an identifier indicating the one or the group of renewable energy generators having produced the energy amount, and the produced energy amount.

In a further step, the energy certificate is encrypted by the computing unit.

As a final step, the encrypted energy certificate is added to a block of a blockchain or a distributed ledger application as a digital output.

The method according to the invention enables issuing a green energy certificate as a Guarantee of Origin (GoO) for a specific energy generating unit at an arbitrary aggregation level. The certificate can be issued for a single renewable energy generator or a group of renewable energy generators. By using a blockchain or any other distributed ledger application and the computing unit, which is part of the energy generating system and therefore close to the renewable energy generating system, it is possible to create certificates of green energy origin that are trustworthy and immutable. Such certificates can be traced back to a single renewable energy generator or a group of more renewable energy generators.

In contrast to current green energy certificates which are issued to customers by a utility, it is now possible to have a peer-to-peer network without having any entity in between the customer and the producer of the renewable energy. However, in case of regulatory reasons, it is possible to have a regulating entity being able to review and audit the transaction of the certificate by being part of the blockchain network.

As a further advantage, each renewable energy generator or group of generators is able to issue an energy certificate worth the energy it generates continuously. To ensure a high accuracy, the produced energy determined by the first energy meter is verified by an independent instance. "Independent instance" is preferably to be understood, that the verification of the produced energy amount is made by means of an instance - e. a device or controller - which is different from the first energy meter or meters.

In a preferred embodiment of the invention, the step of determining the produced energy amount comprises determining a produced energy amount of each of the renewable energy generators by a respective first energy meter, installed at each of the renewable energy generators. Alternatively or additionally, the step of determining the produced energy amount comprises determining a produced energy amount of the group of more renewable energy generators by the first meter, installed a grid connection point of the group of the renewable energy generators. Locating a respective first energy meter at each of the renewable energy generators enables to issue an energy certificate for a specific renewable energy generator. Installing the first meter at a grid connection point of the group of the renewable energy generators enables issuing a certificate for a group of renewable energy generators thereby using a reduced amount of energy meters.

In another particularly preferred embodiment, the step of verifying the produced energy amount comprises determining, by a second energy meter installed at each of the renewable energy generators, a produced energy amount in the predetermined period of time and determining a deviation from the produced energy amount determined with the first energy meter.

In another particularly preferred embodiment, the step of verifying the produced energy amount comprises determining, by a second energy meter installed at a grid connection point of the group of renewable energy generators, a produced energy amount in the predetermined period of time and determining a deviation from the sum of produced energy amount determined with the first energy meters of the group of renewable energy generators installed at each of the renewable generators or determining a deviation from the produced energy amount determined with a first energy meter installed at a grid connection point of the group of renewable energy generators.

It is preferred that the second energy meter or meters is or are different from the first energy meter or meters. Preferably, the technology used for metering energy is different. While the first energy meter or meters may be a measurement equipment provided by the manufacturer of the renewable energy generators, the second energy meter may be an independent measurement equipment or device.

In a further preferred embodiment, the step of verifying the produced energy amount in the predetermined period of time is carried out before issuing the energy certificate. In an alternative embodiment, the step of verifying the produced energy amount in the predetermined period of time may be carried out after encrypting the energy certificate.

It is further preferred when the energy certificate is only issued if the verification of the produced energy amount is positive. In particular, the energy certificate may be only issued if the deviation between the determined produced energy by means of the first energy meter and the verification, in particular by means of the second energy meter, determined is below a predetermined threshold. In other words, the certificate is only issued if the deviation between the two independent measurements is small. In that case, the two independent measurements match, and a certificate is issued.

In another preferred embodiment, the predetermined period of time is in an interval ranging from <NUM> minute to <NUM> minutes, preferably <NUM> minutes to <NUM> minutes, most preferred <NUM> minutes or <NUM> minutes. A <NUM> minutes time interval corresponds to the default averaging period for a wind turbine SCADA system which might be used as a first energy meter. The <NUM> minutes interval is a typical default averaging period of utilities trading certificates between energy producers and customers.

In another preferred embodiment, encrypting the energy certificate is based on an asymmetric cryptographic procedure. However, any other encrypting system might be used as well. Using asymmetric encryption systems enables using the well-known private-public key procedures.

In another preferred embodiment, the blockchain or distributed ledger application is configured such that access is granted to permissioned parties only. In other words, a private blockchain or distributed ledger application is suggested in which, for example the customer, the certificate issuer and a regulator for reviewing and auditing the transaction may be permissioned to access the blockchain or ledger application.

Besides the above method, the invention refers to an apparatus for computer-implemented monitoring of energy production of a renewable energy generating system where the apparatus comprises a computing unit configured to form the method according to the invention or one or more preferred embodiments of the method according to the invention.

Moreover, the invention refers to a renewable energy generating system comprising one or a group of more renewable energy generators, wherein the renewable energy generating system comprises an apparatus which is configured to perform the method according to the invention or one or more preferred embodiments of the method according to the invention.

Furthermore, the invention refers to a computer program product with program code, which is stored on a non-transitory machine-readable carrier, for carrying out the method according to the invention or one or more preferred embodiments thereof when the program code is executed on a computer.

Embodiments of the invention will now be described in detail with respect to the accompanying drawings.

<FIG> shows a schematic diagram illustrating a renewable energy generating system <NUM> which is able to issue an energy certificate <NUM> (also called Guarantee of Origin (GoO)) worth the energy it has generated in a predetermined period of time. The energy certificate <NUM> can be transferred directly (i.e. peer-to-peer) to a customer <NUM> by encrypting the energy certificate <NUM> and adding the encrypted energy certificate <NUM> to a block of a blockchain <NUM> or any other distributed ledger application. Issuing the energy certificate <NUM>, encrypting the energy certificate <NUM> and adding the encrypted energy certificate <NUM> to a block of a blockchain <NUM> is carried out by one or more computing units <NUM> of the renewable energy generating system <NUM>.

The energy generating system <NUM> consists of one renewable energy generator or a group of more renewable energy generators. The renewable energy generating system may be the windfarm consisting of one or a plurality of wind turbines as renewable energy generators or a photovoltaic power plant consisting of one or a plurality of photovoltaic systems. In <FIG>, a single wind turbine is representing an arbitrary number of renewable energy generators <NUM> of the energy generating system.

Issuing the energy certificate <NUM> for the renewable energy generating system <NUM> will be performed, during the operation of the renewable energy generating system, for a predetermined period of time. For example, the energy certificate <NUM> will be issued for each <NUM> minutes or <NUM> minutes time period during the operation of the renewable energy generating system <NUM>. The energy certificate <NUM> may be issued for a specific renewable energy generator <NUM> or the renewable energy generating system <NUM> as a whole.

As each energy certificate <NUM> is issued worth the energy the renewable energy generator(s) <NUM> or the renewable energy generating system <NUM> (depending on the wished aggregation level) it has/have generated for the predetermined period of time, the produced energy amount of the renewable energy generating system <NUM> or renewable energy generator(s) in the predetermined period of time is determined. This may be done by a first energy meter <NUM>, which is, for example, provided by the manufacturer of the renewable energy generator(s) <NUM>. In particular, a respective energy meter <NUM> is installed at each of the renewable energy generators <NUM>. Before issuing the energy certificate for the produced energy for a specific predetermined period of time, the produced energy amount of the renewable energy generator <NUM> or the renewable energy generating system <NUM> is verified.

The step of verifying the produced energy amount may be done by a second energy meter <NUM> which is installed, for example, at each of the renewable energy generators <NUM>. The second energy meter <NUM> is a different energy meter compared to the first energy meter <NUM>. It may be based on the same or a different measurement technology compared to the first energy meter. By comparing the produced energies determined from the first and the second energy meters a deviation can be determined for a desired aggregation level. If the deviation is within a predetermined range, then the energy certificate <NUM> will be issued by the computing unit <NUM>.

If the energy certificate <NUM> is issued for each single renewable energy generator <NUM>, a comparison of the produced energies determined by the first and the second energy meters <NUM>, <NUM>, both of them being installed at the renewable energy generator <NUM>, is made.

If the energy certificate <NUM> will be issued for a group of more renewable energy generators, the second energy meter <NUM> may be installed at a grid connection point (not shown) of the group of renewable energy generators <NUM>. In case that every single renewable energy generator <NUM> is equipped with a first energy meter, the sum of produced energy amounts determined with all of the first energy meters <NUM> of the group of renewable energy generators <NUM> is determined and this sum is compared to the measurement of the second energy meter <NUM>. In an alternative of this constellation, only a single first energy meter <NUM> might be installed at the grid connection point of the group of renewable energy generators <NUM>. If the deviation determined is within a predetermined range, i.e. small enough, meaning that the measurements of the first and the second energy meters <NUM>, <NUM> match, the energy certificate <NUM> will be issued for the group of renewable energy generators <NUM>. Small enough comprises, for example, a deviation smaller than <NUM>%.

The issued energy certificate <NUM> will be encrypted by the computing unit <NUM> with asymmetric encryption. The computing unit <NUM> represents a certificate issuing device. The computing unit <NUM> may make use of a private and a public key pair with a unified identification of the renewable energy generator. Then, a block of a blockchain <NUM> is created and uploaded to the blockchain <NUM> or any other distributed ledger. Creation of the block may be made by the computing unit <NUM> or a different computing unit. The energy certificate's value has an equal size to the generated electrical energy production of the generator.

The first and/or second energy meters <NUM>, <NUM> are preferably located in the renewable energy generators <NUM>. As described above, at least the second energy meter <NUM> may be located at a grid connection point.

According to the location of the first and/or second energy meters <NUM>, <NUM>, the origin of the energy certificate <NUM> can be a single renewable energy generator or a group of renewable energy generators of the renewable energy generating system <NUM>. In case of a group of energy generators <NUM>, the grid connection point might be chosen for measuring the energy production.

The data for produced energy may be taken from an independent smart autonomous meter of the renewable energy generators <NUM>. In particular, the first energy meter <NUM> may be the SCADA system or a condition monitoring system (CMS) of the renewable energy generator <NUM>. Alternatively, data might be acquired by a dedicated measurement system, developed for this specific purpose.

The produced energy in the predetermined time interval may be averaged over this period. Preferably, the produced energy is averaged over <NUM> minutes or <NUM> minutes.

The produced energy for a defined aggregation level and the respective averaging period may be encrypted. Preferably, a public-private key procedure is used.

Different levels of deviation between the determined produced energy amounts of the first and the second energy meters may be used. For measurements within a very precise first energy meter <NUM> very small deviations are accepted. For measurements at a grid connection point higher deviations may be acceptable taking into account grid losses from the units to the grid connection point.

The energy certificate at least comprises a time stamp indicating the predetermined period of time, an identifier indicating the one or group of renewable energy generators <NUM> having produced the energy amount, and the produced energy amount. More detailed, the following parameters may be part of the energy certificate <NUM>:.

When adding the encrypted and signed energy certificate <NUM> to a block of the blockchain <NUM>, the previous and the current hash value are added. The hash value of the previous block is required for linking the blocks together. The current hash is the hash value of the current block.

Preferably, a private blockchain or distributed ledger is used which only grants access to permission parties. Permissioned parties are, besides the energy provider and the customer <NUM>, a potential auditing unit <NUM> which needs to review and audit the transaction of the energy certificate <NUM>. In this regard, only certified parties shall be able to create a new block of the blockchain <NUM>. In this way, it can be ensured that only valid green energy certificates <NUM> are issued. Thus, proof of authority will be applied.

<FIG> shows an alternative embodiment, in which the energy certificate <NUM> is added to a blockchain <NUM>. The energy certificate <NUM> may be provided for the customer <NUM> directly while further transaction steps may be made by a utility (a trading company) <NUM>.

<FIG> shows a flowchart of generating an energy certificate <NUM> according to a first embodiment. In step S1, a produced energy amount of the renewable energy generator <NUM> (representing an energy generating system in this example) is determined by the first energy meter <NUM> for the predetermined period of time, e.g. <NUM> minutes or <NUM> minutes. In step S2, an independent energy meter measures the produced energy amount for the same predetermined time interval. Steps S1 and S2 are conducted in parallel at the same time. In step S3, a deviation between the produced energy amounts determined by the first and the second energy meters <NUM>, <NUM> is calculated. This deviation verification is conducted by the computing unit <NUM> acting as a certificate issuing device. In step S4, it is verified whether the deviation is acceptable. If the deviation between the produced energy amounts measured by the first and the second energy meters <NUM>, <NUM> is too big, i.e. lying without a predetermined range (path "n"), step S5 decides for manipulation or a measurement error. The flowchart ends without issuing an energy certificate. If the deviation is small, i.e. the difference between the produced energy amounts measured by the first and the second energy meters <NUM>, <NUM> is within a predetermined range (path "y"), an energy certificate <NUM> is issued in step S6. As described above, the energy certificate <NUM> at least comprises a time stamp indicating the predetermined period of time, an identifier indicating the renewable energy generator <NUM> having produced the energy amount, and the produced energy amount. In addition, the aforementioned parameters of table <NUM> may be added to the energy certificate <NUM>. As a next step, the energy certificate <NUM> is added with a digital signature to ensure the authenticity and integrity of the data. The computing unit creates a one-way hash of the data to be signed. The private key may then be used to encrypt the hash value. This encrypted hash value, plus other information like the hashing algorithm used, represents the digital signature. The digital signature corresponds to encrypting the energy certificate, as outlined in step S7. In step S8, a block in the blockchain is created and added to the blockchain <NUM>.

<FIG> shows an alternative flowchart. In step S11, the produced energy amount for a predetermined period of time is measured by, for example, the second energy meter <NUM>. In step S12, the energy certificate <NUM> is issued. In step S13, the energy certificate is added with a digital signature, i.e. it is encrypted. Steps S12 and S13 are carried out by the computing unit <NUM> acting as the certificate issuing device. Parallel to measuring the produced energy amount by the second energy meter <NUM>, the energy amount is measured by the first energy meter <NUM> in step S14. In step S15, the deviation verification is made. In step S16, it is verified, whether the deviation is acceptable (path "y" or path "n"). If the deviation is not acceptable (path "n"), in step S17, a measurement error or manipulation is assumed. If the deviation is small (path "y"), in step S18, a block in the distributed ledger or blockchain is created and added to the blockchain <NUM>.

Claim 1:
A method for computer-implemented monitoring of energy production of a renewable energy generating system (<NUM>), where the renewable energy generating system (<NUM>) comprises one or a group of more renewable energy generators (<NUM>), wherein during the operation of the renewable energy generating system (<NUM>) for a predetermined period of time the following steps are performed one after the other:
determining, by a first energy meter (<NUM>), a produced energy amount of the renewable energy generating system (<NUM>) in the predetermined period of time;
verifying the produced energy amount of the renewable energy generating system (<NUM>) in the predetermined period of time by a second energy meter (<NUM>) different from the first energy meter (<NUM>) by comparing the produced energies determined from the first and the second energy meters (<NUM>, <NUM>);
issuing, by a computing unit (<NUM>), an energy certificate (<NUM>) for the renewable energy generating system (<NUM>) for the predetermined period of time, where the energy certificate (<NUM>) at least comprises a time stamp indicating the predetermined period of time, an identifier indicating the one or group of renewable energy generators (<NUM>) having produced the energy amount, and the produced energy amount in case a verification of the produced energy amount is positive;
encrypting, by the computing unit (<NUM>), the energy certificate; and
adding, by the computing unit (<NUM>), the encrypted energy certificate to a block of a blockchain (<NUM>) or a distributed ledger application as a digital output.