Leamus/GettyRenewables are reshaping the global energy sector.Around the globe, we are installing solar panels and wind turbines with unprecedented speed with the aim of curbing climate change.Renewable generation produces relatively little greenhouse gas emissions. However, solar and wind infrastructure have two major downsides: they can make landscapes less appealing in some people’s eyes and take up vast amounts of space.That’s where floating power plants come in. These are floating vessels that carry on-board energy generation systems that channel electricity straight to an onshore power grid. Floating power plants are gaining traction worldwide as a way to provide reliable energy to islands, coastal towns and cities with limited space.So how do these plants work? And what benefits could they bring?What are floating power plants?The concept of floating power plants is not new. In 1931, the cargo ship SS Jacona was converted into a floating power plant, capable of generating temporary electricity. It was the first vessel of its kind and supplied energy to coastal communities along the northeast tip of the United States, which often lost power in severe weather.The development and use of these power plants, such as the converted WWII oil tanker, the USS Saranac, grew after the second world war. In the 1990s, major manufacturers including Westinghouse and Wärtsilä started building floating power barges as a way to provide energy to developing nations.Floating power plants can offer a permanent supply of energy, including for whole cities such as Pevek in Russia and Luanda in Angola. They can also provide temporary power for specific activities such as mining, or during emergencies including natural disasters or when infrastructure fails.There are two main types of floating power plants.ShipsPower ships are self-propelled vessels that are often converted from single-hull bulk carriers, a type of cargo ship. Power ships contain a large-scale power plant, which typically generate electricity from natural gas or hydrocarbons such as heavy oil. These vessels navigate to coastal locations, often in developing countries, or wherever they are required. The Turkish vessel, the MV Doğan Bey, was the first modern self-propelled power ship to become operational. Originally built in 1983 as cargo ship, this vessel was converted in 2010 and was immediately deployed to the power-desperate city of Basra in southern Iraq. Turkey’s Doğan Bey was the first modern power ship to be used to generate electricity. mtcurado/Getty Read more: Renewables need land – and lots of it. That poses tricky questions for regional Australia BargesPower barges are flat-bottomed vessels that don’t have a motor. These are towed wherever they are needed and generate power once connected to local electrical infrastructure.Barges fitted with solar panels and batteries are known as solar power barges. These are particularly useful in river or remote coastal communities, such as Maine in the northeast US, as they can provide energy for near-shore fishing activities such as aquaculture and oyster farming.Solar power barges differ from floating solar arrays, such as the one found at the Drouin wastewater plant in southern Australia. Unlike barges, this solar array floats directly on a lagoon of wastewater and is not transportable. Read more: ‘Failure is not an option’: after a lost decade on climate action, the 2020s offer one last chance Going nuclearBoth power ships and power barges have their downsides.Solar power barges are limited in how much power they can generate, with ranges of just a few megawatts (MW) up to 50MW. And they can only operate in certain places. For example, a solar power barge may work well in sun-drenched countries such as Australia or Japan, but not in Arctic regions that can go without sunlight for roughly four months of the year.Existing power ships are propelled by emissions-intensive crude oil and other hydrocarbons. But as the world races to decarbonise the energy sector, these ships will likely go out of fashion.Given these limitations, attention is shifting to a new type of system: floating nuclear power plants.These plants generate electricity using a compact nuclear reactor. The first working floating nuclear power plant was the Akademik Lomonosov, developed by Russia in the 2010s and powered by two modified nuclear reactors. It was deployed to the remote Siberian city of Pevek in 2019.Floating nuclear power plants like the Akademik Lomonosov produce enough energy to power a city of more than 200,000 people. They remove the need for diesel and the health and environmental risks of black soot, which are particularly harmful to Arctic communities. Their compact design, which allows each reactor to be refuelled separately, ensures power generation is constant.For these reasons, interest in floating nuclear power plants is growing, with communities across the Mediterranean coast, Norway, Japan and India exploring the potential benefits.However, nuclear power poses environmental risks, including the improper disposal of spent fuel and the remote chance of core meltdown.And with only one plant in operation, it’s still early days for the floating nuclear power plant sector. However, Russia and other countries such as South Korea are currently developing plants for both domestic and international markets. Read more: How could Australia actually get to net zero? Here’s how Not a silver bulletThe global interest in floating nuclear power plants raises several legal and regulatory questions.are these vessels technically ships or power plants?how safe are they and what safety regulation is needed?are they governed by international law, including the “law of the sea”, and who is responsible for any safety risks or environmental damage?At present, we don’t have any clear answers to these questions. The American Bureau of Shipping has developed the first comprehensive set of rules for floating nuclear power plants. These requirements are a promising start. However, as Russia and other countries start experimenting with these plants, both national and international legal frameworks must ensure they are used safely and effectively. Read more: Building more renewable energy sources means rethinking land use for agriculture and conservation Tina Soliman-Hunter does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.