By Rebecca Nesbit
Happy New Year! Last year I blogged about the challenges and promises of second-generation biofuels (those made from agricultural by-products such as straw or from woody plants such as poplar). If these crops are going to be a relatively cheap and sustainable alternative to fossil fuels, we will have to think seriously about genetic modification.
Rice is one of the most important food resources in the world. Its cultivation means about 800 million metric tons of rice straw is also produced annually, which is normally burned or decayed in the field. Getting rid of the straw in this way produces greenhouse gasses such as methane. But what if we could use straw, currently a polluting by-product, as a source of energy?
Woody plants, including the inedible part of food crops, get their strength from lignin and cellulose. Cellulose is basically lots of glucose molecules joined together, so a perfect energy source. But the problem is how to turn it into ethanol to use as biofuel.
The process currently relies on enzymes from bacteria or fungi, but it is extremely expensive. If these enzymes could be produced by GM plants rather than by micro-organisms, the production of ethanol would be cheaper and quicker.
Scientists from Taiwan genetically modified rice plants to contain a gene from a bacteria which produces an enzyme that breaks down cellulose. The enzyme they chose has the advantage that it works best at high temperatures, and doesn’t work well to break down cellulose in conditions found in the field.
They managed to produce rice straw with high levels of the enzyme in it, so with potential to increase the efficiency of biofuel production. The enzyme remains stable in the straw long after the rice has been harvested, and becomes active at higher temperatures.
By choosing an enzyme that only breaks down cellulose at high temperatures, this shouldn’t stop the plant growing normally. However, they found some evidence that the genetically modified plants were shorter, so more experiments are needed to work out whether adding the gene for the enzyme disrupts the growth of the rice.
There are clear environmental benefits to using agricultural waste as a replacement for fossil fuels and to making the process of biofuel production more efficient. But is genetic modification a viable, sensible, or even essential option? As always, I’ll be interested to hear your views.
Chou, H., Dai, Z., Hsieh, C., & Ku, M. (2011). High level expression of Acidothermus cellulolyticus beta-1, 4-endoglucanase in transgenic rice enhances the hydrolysis of its straw by cultured cow gastric fluid Biotechnology for Biofuels, 4 (1) DOI: 10.1186/1754-6834-4-58
The Government is proposing to susidise bioenergy projects as it tries to meet renewable energy targets. Its plans, according to the RSPB, are potentially damaging to habitats and do not deliver necessary reductions in greenhouse gas emissions.
By 12th Jauary, the RSPB are asking people to send a letter or email urging the Government to stop subsidies to large-scale energy-only plants. The details of what the problem is, what to say, and where to post it to can be found here. This campaign is by no means anti-biofuel, it is just anti the proposals as they stand.
I’ve just written – it shouldn’t take long!
by Rebecca Nesbit
Each year, 7.2 million tonnes of fisheries catch gets thrown away as bycatch, including fish, turtles and birds.
Modifying fishing gear is a popular way of reducing this, and to a large extent it can often be effective. However, suitable modifications aren’t always possible, so preventing fishing in certain areas can be the only way to solve the problem. As I’ve blogged before, this brings its own challenges.
A recent paper in PLoS looked at options of biodiversity ‘off-setting’ for seabirds caught as bycatch, much in the same way that carbon offsetting is popular for plane travel. It’s widely acknowledged that this isn’t a long-term solution, but in the short term it may be possible to save more birds by putting money into conservation schemes than it would be by modifying equipment or creating exclusion zones.
Tuna and squid fishing in particular leads to a bycatch of albatross, petrels, and shearwaters which get caught on the hooks of longlines. However, these birds often face a far greater danger in their breeding grounds from invasive mammals, particularly rats and feral cats, which have decimated many seabird colonies. The problem is so severe that most vertebrate extinctions over the past six centuries have been caused by invasive mammals.
To test the idea of biodiversity offsets, this paper uses the example of the tuna fishery which stretches along the east coast of Australia. The main victims here are flesh-footed shearwaters. Possible solutions include only laying lines at night and weighting the lines so they sink out of reach more quickly. These have helped but they can’t eliminate bycatch, and they’re expensive, potentially dangerous to use, and hard to enforce. The authors point out that “like world peace, bycatch elimination cannot be achieved over night”.
The shearwaters are also facing threats in their island breeding colonies, including habitat loss, ingestion of plastic, and predation by rats.
Hopefully, better technical solutions to reducing bycatch will be available in a few years time, so rather than implement what we currently have available, it’s perhaps better to look to other conservation measures to give the shearwater population ‘breathing space’ until a real solution is found. Eradication of rats would benefit the whole island ecosystem, not just the shearwaters. In the example of the flesh-footed shearwaters, eradicating invasive rodents is at least 10 times more cost effective than closing areas of sea to fishing.
The way I see it is that, if I was given a pot of money to save seabirds I would spend it on saving the most birds possible. So if the fishing industry has money to use for conservation maybe it is best put to use on islands not boats. However, biodiversity offsets should be a way of saving more birds, not of saving money.
Another interpretation is, of course, that we shouldn’t eat tuna. It’s delicious, and I do miss it…
Pascoe S, Wilcox C, & Donlan CJ (2011). Biodiversity offsets: a cost-effective interim solution to seabird bycatch in fisheries? PloS one, 6 (10) PMID: 22039422
by Rebecca Nesbit
In the race to achieve fuel security and to reduce our reliance on fossil fuels, the US has rapidly increased the volume of bioethanol it produces, from 6.2 billion litres/year in 2000 to 50 billion in 2010. Ethanol has the advantage that it can be mixed with petrol so cars need no conversion. However, most of this growth in ethanol has been from first generation corn ethanol, produced through fermentation. First generation biofuels have the major drawback that they are energy intensive to produce, which can counteract any reduction in green house gas emissions. Also, there is a raging food vs fuel argument surrounding biofuels made from food crops.
To overcome some of these problems, research is taking place into second generation biofuels, made from materials such as forestry wastes, grasses, wastepaper etc. These can be converted into liquid fuel, normally using enzymes. But pre-treatment steps are needed to make the enzymes more effective, and options include grinding, adding acid, steaming, or treatment with fungi. Many of these, however, haven’t made it out of the lab. A paper available this month from Biotechnology for Biofuels predicted trade-offs between different pre-treatment steps for commercial ethanol production from grass straw.
For the same amount of straw put in, using dilute acid, dilute alkali or hot water as pre-treatments produced similar quantities of ethanol. Steam explosion pre-treatment was slightly less effective so yielded less ethanol.
Costs of the plant were highest for alkali pre-treatment, and similar for the other three options, with steam being the lowest. The ethanol production costs varied by a few cents per litre ($0.84 per litre for dilute acid, $0.89 for dilute alkali, $0.81 for hot water and $0.86 for steam explosion). Water use also varied – the thirstiest treatment actually being alkali not water.
They concluded that ethanol price and energy use were highly dependent on the pre-treatment technology, demonstrating the importance of addressing the tradeoffs in costs and environmental impacts of different aspects of the pre-treatment.
New technologies are set to make bioethanol more efficient and less energy intensive to produce, which in turn reduces its environmental impact. Biofuels made with current technologies may give biofuels a bad name, but as technologies making second generation biofuels viable move beyond the lab, their environmental impact will reduce. And there don’t seem to be many viable options available for feeding our cars, so research such as this can shape our future fuel supply.
Deepak Kumar and Ganti S Murthy (2011) Impact of pretreatment and downstream processing technologies on economics and energy use in cellulosic ethanol production
Biotechnology for Biofuels, 4:27 doi:10.1186/1754-6834-4-27
by Rebecca Nesbit
In today’s population of just over 7 billion people, more than 900 million are undernourished and over 2 billion have nutrient deficiencies, yet over 1 billion adults are overweight. Lots of work has gone on to address the problems of undernourishment and obesity, but the problem of nutrient deficiency has taken second place.
Much of the world has moved towards growing fewer types of foods, and in many places agriculture is now dominated by cereals. However, diverse diets generally provide greater nutrition and have been associated with health benefits, from lower mortality rates to a reduced chance of developing cancer.
In sub-Saharan Africa 40% of children are chronically undernourished or stunted, and food security initiatives must take nutrients as well as calories into account. A study recently published in PLos ONE examined diet diversity in villages in Malawi, Rwanda and Kenya where malnutrition and food insecurity are high.
To measure diet diversity, the study successfully used a technique that is usually applied to species diversity. They produced a value for each individual farm, where a higher value means the farm’s produce provides greater nutritional diversity. The value is based on the number of plant species on the farm with unique nutritional make-ups. It’s different to simply recording the number of species because some types of food will have the same nutritional content.
Quantifying things in this way helped them identify which species were particularly important – i.e. those which provided the nutrients that none of the other foods did. Mulberry, for example, provided vitamin B complexes.
It also provided interesting insight into redundancy, which refers to how many species there are with each nutritional composition. Two farms may have the same value for nutritional diversity, but if one has a greater redundancy then it is less vulnerable if individual species are no longer grown, perhaps due to disease or changing climatic conditions.
The study found variation between the farms in the values for nutritional diversity, for example mineral diversity was lower in Malawi than Uganda or Kenya. The soils in these Malawian villages were also poorest. This could mean villages are unable to grow such a range of plants, or the low fertility could be precisely because they only grow a small number of species.
Decades of research have given us a better understanding of how the body uses nutrients, allowing us to consider all these nutrients together when planning agricultural systems to increase food security. This paper explains the importance of nutritional diversity and comes up with a practical way of measuring it.
Remans R, Flynn DF, DeClerck F, Diru W, Fanzo J, Gaynor K, Lambrecht I, Mudiope J, Mutuo PK, Nkhoma P, Siriri D, Sullivan C, & Palm CA (2011). Assessing nutritional diversity of cropping systems in African villages. PloS one, 6 (6) PMID: 21698127
by Rebecca Nesbit
The relationship between conservation and economics is a complex one. We rely on the natural world for vital services. Without these we wouldn’t even have an economy – they are everything from pollination through to water purification and climate regulation. But on a local scale there are often trade-offs, at least in the short term. Saving endangered species can be expensive.
A paper published this month by researchers from the University of Alberta (Canada) looked at a trade-off between proposed industrial developments and protecting habitats the industry would destroy.
How you choose which areas of land to preserve is a much-debated issue. In this paper they worked on the premise that by protecting every ecosystem type in the area most species will have their needs met.
Oil and gas extraction and forestry occur across much of Alberta’s forested areas. There is concern that the cumulative environmental impact of this isn’t being addressed, particularly in the oil sands. As a result there are plans to create biological reserves to protect the species within them. This paper takes a new approach to choosing where to locate these reserves, based partly on the trade-offs between conservation targets and economic costs (including lost revenue from not using that land for industry).
They found that the proportion of the area which is protected could double from 15% to 30% while maintaining access to 97% of the region’s resources. This is partly because the presence of oil sands means much of the valuable resources are concentrated in a small area. So the oil sands can be seen as an enabling factor for conservation in Alberta, not a barrier; economic activity can be concentrated in a small area yet provide valuable revenue which can be directed towards conservation nearby. Of course other environmental concerns about the industry, such as pollution, still need to be addressed.
Choosing reserves based only on the economic value of the resources within them, however, doesn’t maximise their biological benefit. When coming up with the best reserve design for the region the study also took into account how connected the reserves were. Small isolated reserves are often less successful because populations within them often go extinct and are not replaced through migration. The study instead suggested three new large reserves.
It’s good to see a move away from pitting industry and conservation against each other, but recognising that they are essentials which must occur alongside each other. The authors of the study hope their approach will be applied more widely to make wise choices about the design and location of nature protection areas and of industrial developments.
Schneider, R., Hauer, G., Farr, D., Adamowicz, W., & Boutin, S. (2011). Achieving Conservation when Opportunity Costs Are High: Optimizing Reserve Design in Alberta’s Oil Sands Region PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023254