The energy sector is in the midst of a significant shift. As technology develops, the way homes, vehicles and businesses are powered is changing.
Over the past year, CNBC's Sustainable Energy has featured innovative ideas that could help to shape the planet's energy future. Below, we take a look at some of the most interesting.
The vehicles that move around our towns and cities may look pretty familiar from the outside, but significant change is afoot under their bonnets.
Take electric cars. Worldwide sales hit 1.98 million in 2018, according to the International Energy Agency (IEA), with global stock exceeding 5.1 million. The previous year, 2017, also saw more than one million sales according to the IEA, with the amount of electric cars on the road exceeding 3 million, a more than 50% increase compared to 2016.
Several automotive firms have made major plays in the electric vehicle sector over the last few years. In November, for instance, the Volkswagen Group officially started series production of its ID.3 electric car.
A few months earlier, in July, Renault and the Jiangling Motors Corporation Group officially set up a joint venture for electric vehicles in China.
Just how important will electric vehicles be in the years ahead?
"I envision all forms of urban transportation shifting to electric vehicles, whether it's electric cars, electric buses, electric trains and even electric airplanes for urban air mobility," Anita Sengupta, an aerospace engineer and co-founder of Airspace Experience Technologies, told CNBC.
Sengupta acknowledged there were challenges related to the adoption of electric vehicles, with some people worried about their range. "That, certainly, is a real concern," she added. "But ultimately, the adoption has to come from both the private sector and the public sector."
While electric vehicles are generating a lot of debate and discussion, could hydrogen-powered transport also have a role to play in the years ahead? One firm, based in Wales, thinks so.
Riversimple is developing a two-seater car which uses a hydrogen fuel cell. An engineering prototype of the car, which is called the Rasa, weighs 580 kilograms, according to the company.
Each wheel of the Rasa hosts an electric motor, and it has clocked speeds of more than 60 miles per hour. Water is a by-product of the process used to power the car.
"(A) hydrogen powered car is effectively an electric car, so you still have an electric motor and the car is still quiet," Nicolas Sergent, who works on design and engineering at Riversimple, told CNBC's Sustainable Energy.
"But instead of running off a battery which stores the electricity chemically, it's running off a fuel cell, a hydrogen fuel cell," he added.
Hydrogen and solar may be helping to shape the planet's future transport mix, but renewables are also having an impact on the buildings we live and work in.
Based in south London, Repowering London is a non-profit organization which says it specializes in "facilitating the co-production of community-owned renewable energy projects."
By working with both community groups and local authorities, it aims to among other things, cut carbon dioxide emissions through the production of de-centralized, low-carbon energy; fight fuel poverty; and generate training and employment opportunities for communities.
The organization's model enables local communities to invest in solar projects. Profit from the sale of electricity to the grid is used to benefit the community and give investors an annual return.
Agamemnon Otero is co-CEO of the organization. He told CNBC's Sustainable Energy that Repowering's vision was, "solar panels on social housing, where communities come together in one vote, one share co-operatives, and share in the energy savings and reductions and also in the idea that they are making a direct impact on global climate change."
While sources such as solar and wind power are renewable, they are not constant: the wind does not always blow, and the sun does not always shine.
However, there are ways to overcome such issues. On Reunion Island — a French island located in the Indian Ocean — one firm specializes in solar energy forecasting and developing technology to "improve the short-term predictability of solar generation."
Called Reuniwatt, the business offers a range of services including day-ahead, intra-day and intra-hour solar forecasts.
Caroline Lallemand is a geographic information system engineer at Reuniwatt. "In order to measure, then forecast, solar energy, Reuniwatt uses a multitude of data sources: satellite observations, weather models, ground sensor measurements and sky images," she told Sustainable Energy.
"I design the pipelines to collect, clean, aggregate and share the data with the rest of the team," she added. "The goal is to make sure that the forecasts that we send to our clients are always the most accurate."
As the last 12 months of Sustainable Energy have shown, companies and organizations around the world are developing business models and technologies that have the capacity to transform the way people live and work. Stay tuned for more innovative, thought-provoking ideas in 2020.