Could high-end camping gear save lives around the world?
When two engineers at a sleek New York design company started making an ultra-efficient cook stove, they had their own holidays and camping trips in mind. Now, they are betting their technology will save lives in rural communities across the world.
Every day about three billion people across the developing world cook their dinner over an open fire inside their homes.
In the process, they expose themselves to thick smoke thought to kill four million people each year, according to the Global Burden of Disease 2010 study.
Studies suggest it could be worse than smoking two packs of cigarettes a day.
In addition, the soot from these fires releases more black carbon into the air than all the world's road traffic.
For years, engineers and development experts have been designing stoves to reduce smoke and make cooking safer.
But a new kind of stove made by the New York-based BioLite, a firm better known for its recreational camping equipment, now claims to cut emissions by more than 90% while producing enough extra energy to charge a mobile phone or power a light bulb for a few hours.
Many mobile users without access to electricity spend more money on charging their phone than on airtime.
Most traditional stoves are smoky because the fuel does not have enough air around it while burning, creating toxic by-products such as carbon monoxide and soot.
But the BioLite stove has a fan that pushes fresh air over the fuel as it burns, enabling what is known as "complete combustion", a process that gets more energy out of the fuel, making it last longer and give off less smoke.
"If you see a car driving down the street and you see smoke coming from the [exhaust] pipe, I think we would all agree that's a badly tuned car," says BioLite chief executive Jonathan Cedar.
"With stoves, the smoke comes when the fuel doesn't burn completely."
The fan is powered by a small "thermo-electric" generator that runs on the heat of the flame, so the stove can serve communities with no access to electricity.
"Compared to the best-in-class simple stoves - stoves that don't have fans to improve emissions - we're typically between four and six times better," Mr Cedar says.
The technology is almost unique, with just one other organisation, African Clean Energy based in the southern African country of Lesotho, selling a stove with a fan.
Despite the huge need for stoves such as these, the technology still faces a big challenge.
The market for stoves is nascent. African Clean Energy produced about 15,000 stoves this year, and even the bigger manufacturers - which make cheaper, simpler "rocket stoves" - sell between just 75,000-100,000 stoves per year.
Historically, it has been difficult to make large numbers of people switch from the open-fire stoves they are used to.
"Cook stoves don't sell themselves in the way a mobile phone would," says BioLite managing director Ethan Kay, who is designing the company's marketing strategy.
Government programmes that subsidised stoves or gave them away have also undermined the idea that cook stoves are worth spending money on.
But BioLite thinks the electricity the stove can produce will appeal to men - crucial because in many target communities men are in charge of the family's money - and make the cook stove an "aspirational" item.
"That requires educating people about the benefits of the product, demonstrating how they work, and crucially, getting buy-in from the husband," Mr Kay says.
Even without the charging function, Ruben Walker, co-founder of African Clean Energy, says people are prepared to pay for "smokeless" cook stoves.
"Customers are wide-eyed when they see our demonstrations," he says. "Poor people don't want to be sold junk, and they don't like to see themselves as poor.
"It isn't hard to get people to switch."
Yet even customers who want a clean cook stove may find it hard to pay for it.
According to Mr Walker, the African Clean Energy stoves cost $70-$100 (£44-£62), but an ideal price for his customers would be closer to $20.
Jennifer Tweddell, manager of impact investing and carbon finance at the Global Alliance for Clean Cook Stoves, says companies could use carbon credits to make the stoves more affordable.
Carbon credits are paid by companies or organisations that release carbon into the air, and are given to groups that save carbon that might otherwise be used. One credit is worth one metric tonne of carbon dioxide, and the price of the credit is set in a carbon market.
"The current carbon market conditions are actually quite favourable to these kinds of companies," she says. "A cook stove carbon credit brings benefits above and beyond just reduction of [carbon dioxide] CO2 emissions.
"There is a potential livelihood benefit, because families are reducing the proportion of their income they are spending on fuel as well as employment opportunities.
"There are health benefits, depending on the emission levels of the stove, and there are benefits towards women."
At Dalberg, the development advisory firm, partner Gaurav Gupta says that cook stove sales need to gain momentum in order to really take off.
"If you have one in seven or one in eight people having [a stove], that itself starts driving the aspiration," says Mr Gupta.
"You simply have to drive penetration to that 10%-20% inflection point. If you can get to that level then you will have 70% to 80% penetration sooner or later."