**6. Problems and risks**

Naturally, there are some problems and limitations, associated with the use of the blockchain. One of them is the limited memory of the blockchain; for example, the memory size of the Bitcoin blockchain in mid-June 2018 was 171 GB. Another matter is a decrease or even lack of confidentiality, because each network user has a wallet address, assigned personally to him or her, and all network members can trace, what transactions were made from it.

In some cases, the use of blockchain is associated with significant energy consumption. Thus, according to a number of data, by the end of 2018, the Bitcoin mining took about 0.5% of the total energy consumption of the entire planet. In addition, one more weakness is the possibility of significant delays in confirming transactions due to problems with mempools (queues of transactions waiting for confirmation by miners in the network) [37].

At the technical level, breakthroughs are needed. The problem of network bandwidth is acute, since the blockchain copies all the information generated earlier into new blocks, so the amount of information in the next block is greater than in the previous one. Potentially, the amount of information in the blockchain tends to infinity, and eventually this problem will have to be solved once by revising the blockchain model.

One of the advantages of the blockchain—its consistent decentralization, creates certain difficulties. Decentralization hinders government oversight and, in many countries, it hinders the development of technology. Regulatory (in particular, fiscal) authorities should recognize the technology. To win their trust, it is necessary to make some efforts, both technological and in PR.

Blockchain transactions, like all commercial transactions, are associated with certain risks, and they have a number of significant features in this special case. These features of risks should be taken into account, when a business, related to the use of blockchain, is insured. In order to pay the insurance indemnity, the insurance company requires data, confirming the insured event, and checks the accuracy of this information. The big data and blockchain technologies should provide such possibility; corresponding data should be recorded, protected from falsification, stored indefinitely, and available to the insurer.

These properties, if it they reliably ensured, create new opportunities for the insurance business. Insurance information can be recorded on the blockchain, providing technical opportunity for data exchange between insurance companies that have joined the blockchain. Such data as customer's insurance history, claims records, etc. allows to assess better the level of risk for a particular customer. The exchange of information can be organized more widely, for example, between insurance companies and hospitals to prevent health insurance fraud. The use of network technologies creates opportunities for more accurate insurance analytics, which facilitates the creation and maintenance of insurance contracts.
