As we shift towards a more sustainable lifestyle, our next sources of energy might come from some surprising places

In 2011, Worcester Council found itself at the focus of local ire when it unveiled plans to warm a local swimming pool using excess heat from a crematorium.

Redditch Crematorium can reach temperatures as high as 800C, all of which was being lost to the atmosphere. The council said using some of this heat to keep the water warm at Abbey Leisure Centre would save them £15,000 per year in fuel bills, but a local funeral director branded the plans as “eerie” and “strange”.

A union weighed in, saying the council’s proposals were “sick and an insult to local residents”. But the project went ahead, making Worcester Council the first local authority in the country to use heat from a crematorium as a form of green energy in a scheme that subsequently won a Green Apple award for environmental innovation.

This council isn’t the only organisation looking at alternative renewables. In London, there are 500 homes that make use of the heat generated by trains running on the London Underground network.

Stockholm’s railway station has gone a step further. The station’s ventilation system recycles body heat from Stockholm’s 250,000 daily commuters as well as from its shops and restaurants. While there are other sites that have successfully utilised body heat to warm their own buildings, Stockholm’s real achievement was in using this energy to power a completely separate building, the 13-storey Kungbrohuset office block, which is 90m down the road.

Far from being a gimmick, the system saves the office block around 20 per cent of its heating costs each year and easily covers the cost of installation and maintenance.

You’ve probably heard of biodiesel, but probably not Bio Bean. The latter is a company created by an architecture student, Arthur Kay, to harness the power of coffee waste.

With most coffee shops discarding 10kg of coffee each day, the company’s founder Arthur Kay says harnessing the potential energy in coffee makes ecological and commercial sense. Coffee is highly calorific, meaning it burns at a high temperature.

The fumes that coffee grounds give off in the landfill are 28 times more potent than CO2 (Vernon Chan)

Kay’s firm produces a range of products, including Coffee Logs, described as “high-performance, sustainable briquettes” that are ideally used as alternative fuels in domestic fireplaces. They’re now on sale at Whole Foods and Blue Diamond and online at Abel & Cole.

Coffee can also be used to create biodiesel, as can chocolate and the fats that are being dug out of our sewer systems. But while biodiesel still produces CO2, albeit from renewable sources, the production of chocolate also results in a waste substance that can be fed to E.Coli bacteria, which in turn produces hydrogen, a CO2-free source of power.

When coffee waste is allowed to go to landfill it breaks down and releases methane, a gas that has a powerful greenhouse effect 28 times more potent than CO2. In Africa, vast underground deposits of methane created by ongoing volcanic activity is resulting in the phenomenon of “exploding lakes”. Trapped gas building up beneath these lakes is periodically released into the atmosphere in a sudden event that has historically killed thousands of people.

Today at Lake Kivu, or the “killer lake”, in Rwanda, some of that gas is being harnessed to power an electricity plant as part of the Kivuwatt Biogas Project. It is hoped that the scheme will be transformative for Rwanda’s energy market and wider economy.

Trapped gas building up beneath lakes like this one in Rwanda create volcanic activity known as 'exploding lakes' (Adam Jones)

But while none of these technologies is likely to offer a direct alternative to the fossil fuels we use today, there has long been hope that algae could be harvested in sufficient volumes that would allow it to become a major source of renewable energy.

In many ways algae appears to be the ideal fuel of the future. It produces more heat than corn or sugar, the growth of algae effectively recycles the CO2 emitted by burning it, it doesn’t compete with high-grade arable land for space and can grow in very poor quality water. This last point opens up the possibility of using certain algaes to treat polluted rivers and lakes.

Chad Wocken, a senior research manager at the Energy & Environmental Research Centre, has also suggested that algae could be vastly more productive than the crops currently used to produce biofuels.

This image shows a tubular glass photobioreactor for the cultivation of microalgae and other photosynthetic organisms.

“Unlike traditional oilseed crops, which produce 10 to 100 gallons of oil per acre, algae are mega oil producers capable of producing 1,000 to 5,000 gallons of oil per acre,” he explains in Biomass magazine. While the economics of running algae farms are yet to become sustainable, the Algal Biomass Organisation believes oil from algae could reach price parity with fossil-based oils as soon as next year.

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According to the US Energy Department, algae could produce 60 times as much fuel per acre as land-based plants and could even be developed next to existing power stations, feeding directly off the CO2 output of the plant.

So why hasn’t algae been developed as an energy source?

“Many challenges to large-scale algae-derived renewable fuel exist,” Chad Wocken writes. “[They] span the entire process from algae strain selection, through harvesting, to fuel conversion.

“Although great strides have been made, algae production remains a challenge. Algae grow in shallow ponds or bioreactors where they use photosynthesis (sunlight, CO2 and other nutrients) to grow, reproduce and generate oil. Advancements are needed to optimise the supply of light, CO2, and nutrients to the algae.”

Reflecting on these setbacks, the then Chair of ExxonMobil and now US Secretary of State, Rex Tillerson, suggested last year that it could take another 25 years for algal fuel to be commercially viable, despite Exxon having invested $600m in the technology since 2009.

The algae-powered building in Hamburg was completed with 200 square metres of 'integrated photo-bioreactors' (NordNordWest)

A small glimpse into an algae-powered future emerged in 2013, when a building in Hamburg was completed with 200 square metres of “integrated photo-bioreactors” forming its outer facade. These glass panels contain micro-algae that produce heat and biomass, which means the entire building is effectively powered by algae.

A water circuit running through the “bio-adaptive facade” keeps the algae supplied with nutrients. In situ, the algae also provides the building with shade until there is a sufficient algal bloom to be harvested and processed at the property’s on-site biogas plant.

Jan Wurm, a research leader at Arup, the BIQ building’s developer said: “As well as generating renewable energy and providing shade to keep the inside of the building cooler on sunny days, it also creates a visually interesting look that architects and building owners will like.”

Our more conventional renewables, solar and wind power, have progressed significantly in recent years, with solar rapidly gaining efficiency while becoming cheaper to build and operate.

But scientists have also raised the prospect of utilising “solar wind”, the plasma stream emitted by the Sun that causes the Aurora Borealis phenomenon. Solar wind consists of charged electrons and protons that leave the Sun’s upper atmosphere at around one million miles per hour.

Solar wind has already been used to power satellites and scientists have proposed that it could generate electrical energy for our day-to-day activities on Earth.

One version of the Dyson-Harrop satellite would use a 0.4 inch copper wire, measuring 1km, suspended over a huge 8,400km wide “solar sail”; the copper would have the effect of creating a magnetic field that captures the charged particles.

The researchers who developed this concept say that such a system would generate 1 billion billion gigawatts, or 100 billion times as much energy as we currently require, but getting that energy back to Earth would be extremely difficult. A smaller satellite, 300m long, would produce enough power for 1,000 homes, according to the researchers.

Back on Earth, EnviroMission has looked into utilising the power of the sun in another way. Rather than converting solar energy directly into electricity, its proposed solar tower would use hot air captured from a desert environment, funnelled into pipes that drive a series of turbines.

Solar updraft towers have been proposed in various forms for more than a century. Their proponents say they have significant advantages over photovoltaic solar panels. The towers have the potential to be almost entirely passive and require minimal maintenance over the long term. As they only require warm air to operate, they can also keep going through the night.

In order to generate 200 megawatts of electricity a year, EnviroMission says its current working model assumes the tower would need to be more than 700m tall. The company says such a tower would be fitted with 32 turbines and could power 100,000 homes.

A much smaller model has been trialled in Spain by Schlaich, Bergermann and Partner. It generated 50 kilowatts of electricity a year and outlasted its planned operational life by six years before it toppled over during a storm. And while 50 kilowatts is a long way off EnviroMission’s goal, but the company says it shows proof of concept.

EnviroMission says a full scale version of the tower is likely to cost $700m but, as with any untested technologies, the true cost is hard to determine. Another firm, Hyperion Energy, has put forward its own proposal for a 200-megawatt updraft facility, with a 1,000m tower and a price tag of $1.87bn.

The funding required for the large solar updraft towers underlines the major sticking point for these technologies – the high costs of research and development. They often make risky investments, with returns only likely to be seen far into the future, making them less attractive to private investors.