  This paper investigates how to efficiently and economically deliver offshore
energy generated by offshore wind turbines to onshore. Both power cables and
hydrogen energy facilities are analyzed. Each method is examined with the
associated proposed optimal sizing model. A cost-benefit analysis is conducted,
and these methods are compared under different scenarios. Three long-distance
energy transmission methods are proposed to transmit offshore energy onshore,
considering the capital/operation costs for related energy conversion and
transmission facilities. The first method that deploys power cables only is a
benchmark method. The other two methods utilize a hydrogen supercenter (HSC)
and transmit offshore energy to and onshore substation through hydrogen
pipelines. For the second method, electrolyzers are placed at offshore wind
farms connected to HSC with low-pressure hydrogen pipelines. For the third
method, offshore wind power is distributed to the HSC and then converted into
hydrogen using electrolyzers placed at the HSC. An offshore scenario including
three wind farms located in the Gulf of Mexico and one onshore substation is
used as the base test case. Numerical simulations are conducted over a planning
period of 30 years using the proposed optimization models for each method
separately. Simulation results show that the proposed hydrogen-based methods
can effectively transmit offshore energy to the onshore substation. The
distances between the wind farms can influence the selection and configuration
of the offshore wind energy system. Moreover, the proposed study analyzes the
cost and benefits for various systems with different energy carriers. It can
also suggest which method could be the best candidate for offshore energy
delivery system under which scenario and demonstrate a promising future for
offshore wind power generation.
