Solar cells and wind farms are commonly referenced in the fight against climate change, but there is another, often overlooked, form of energy production that is already playing a sizable role. Bioenergy, which includes both biomass and biofuel, has been adopted by governments around the world as a viable method for generating carbon-neutral power, at least until the reliability and cost of other renewables improves.
A green delusion
Of late, bioenergy has come under attack, both for pulling investment away from other green technologies and for not being low-carbon. In October last year, more than 100 organisations from across the world signed a joint declaration arguing against the expansion of bioenergy projects, referred to as the ‘Biomass Delusion’.
Bioenergy has come under attack for pulling investment away from other green technologies
Recent developments in the field of bioenergy, however, have provided renewed hope that it can play a role in a green future. Last year, the US Department of Energy committed $80m of investment to bioenergy research and development, with the aim of producing more affordable and sustainable non-food dedicated energy crops.
Evidently, the jury is still out as to whether bioenergy is a useful tool in the fight against climate change. There have been open letters pledging their support, while others have been heavy with criticism. In order to bring everyone onside, bioenergy proponents will have to convincingly argue that burning biomass, or converting it into ethanol, is not a net contributor to carbon emissions and that crops for energy can be grown on a mass scale without negatively impacting food security.
Cream of the crop
Global population levels are set to hit 9.8 billion by 2050 and 11.2 billion by 2100, according to a 2017 United Nations report. Obviously, this growth will facilitate the need for heightened levels of energy production – but it will also mean many more hungry mouths to feed. If citizens are forced to choose between food and fuel, few will plump for the latter.
Consequently, there are concerns that any increase in the use of bioenergy will come at the expense of agricultural land that could be used for food crops. According to Global Food Security, a UK cross-government programme on food security research, the planet will need to produce more food in the next 35 years than it has produced in the entirety of human history. The likelihood of achieving such a goal will be made more difficult by changing dietary habits, increasing urbanisation and rising sea levels.
Predicted global population by 2050
Predicted global population by 2100
Invested by the US Department of Energy in bioenergy R&D last year
of global energy supply comes form bioenergy
Dr Naomi Vaughan, Senior Lecturer in Climate Change at the University of East Anglia, told The New Economy that the growing demand for bioenergy crops could potentially exacerbate food security issues if “it was poorly regulated”. However, recent developments suggest that bioenergy and food crops can be grown in parallel rather than in competition.
Scientists at the University of Illinois are looking at ways of creating bioenergy-suitable crops that can be grown on the type of marginal land that is unsuitable for agricultural cultivation. In particular, they are investigating whether hybrid strains of elephant grass can be bred that will produce enough biomass to make them a viable fuel source even in low-temperature environments.
The resilience of elephant grass has long been recognised, but the plant has only recently been considered a potential bioenergy crop. Elephant grass, or miscanthus giganteus, is a naturally occurring hybrid produced by crossing two other Asian grasses, miscanthus sacchariflorus and miscanthus sinensis. In Eastern Siberia, a strain of miscanthus sacchariflorus was recently discovered growing in temperatures as low as minus three degrees Celsius. By studying these grass crops further, there is hope that even hardier hybrids can be created that can provide fuel in climates where food production is not an option.
“Miscanthus giganteus is exciting for a number of different reasons, the most obvious being that it is very productive in temperate regions compared to other highly productive crops – the obvious comparison here would be corn,” explained Charles Pignon, a postdoctoral research associate at the University of Illinois at Urbana-Champaign. “It is able to be very productive, while also being very resource-efficient. It doesn’t need too much fertilisation, it can grow well on marginal soil and even though it originates from Eastern Asia, the hybrid we use is sterile, which reduces its risk as an invasive species. These are the reasons for miscanthus’ broad appeal.”
Grasses are not the only viable bioenergy crop that scientists are looking at. Last year, a Texas A&M AgriLife Research study found that high biomass sorghum can be grown in water-stressed conditions and still produce significant yields – as much as 10 tons per acre. Other researchers are looking at growing the tamanu plant, another bioenergy crop, on peatland that is unsuitable for any other purpose. These developments show how bioenergy can make better use of the planet’s resources rather than being just another drain on them.
Seeds of doubt
A criticism often levelled at proponents of bioenergy is that it is not actually carbon neutral. When trees are cut down and burned to create energy, it is certainly true that bioenergy is a net contributor to atmospheric CO2 levels because carbon is released immediately, which will then take years to be sequestered by new plant growth. However, Pignon argues that it would be wrong to paint the bioenergy field with too broad a brush.
“There are lots of different crops and systems that can provide feedstock for bioenergy,” Pignon said. “With woody feedstock, it does take a while for carbon to be sequestered, but that isn’t the case with a perennial feedstock or a plant like miscanthus. Because the plant is harvested every year, the harvested biomass only contains the carbon that was sequestered over the past year, not over the past several years. In addition, we only harvest the above-ground part of the plant. So with a system like miscanthus, you have a real opportunity to achieve negative CO2 emissions.”
Distinguishing between the different forms of bioenergy is important if businesses and governments are to approve projects that truly grant environmental benefits. It is essential that the issues raised by bioenergy opponents are considered, but they shouldn’t dominate the dialogue. If bioenergy projects avoid using productive forests for combustion, they can ensure that forest carbon stocks at least remain stable. Effective forest management can ensure that bioenergy does not have a detrimental impact on the atmosphere or woodland ecology.
According to Vaughan: “The key challenge for sustainable biomass energy is strong governance and regulation to minimise negative impacts such as deforestation, biodiversity loss, food security issues or negative impacts on local communities.”
If this challenge can be overcome, bioenergy – whether it comes from burning trees or converting organic matter from perennial plants into ethanol – can play a part in a green future. What’s more, there are other benefits of bioenergy crops that aren’t always considered. The roots left in the soil by perennial grasses, for instance, help improve soil dynamics in a way that food crops do not.
Moreover, if scientists can grow bioenergy plants on land that was previously considered useless, then the economic benefits for communities in these areas could be huge, opening up new agricultural revenue streams. Farmers in locations susceptible to drought may find that bioenergy crops provide more reliable harvests than those dedicated to food.
Currently, bioenergy accounts for approximately nine percent of the world’s energy supply, but much of this still concerns the burning of biomass in less-developed countries. If bioenergy is to play a greater role in the energy make-up of the future, it needs to greatly increase its scale and sophistication. Scientists and agribusinesses will play their part, but so too must politicians, who should put the right regulatory frameworks in place to ensure that bioenergy has a positive effect on communities both locally and globally.