Biomass is a renewable source of energy derived from organic matter, such as plants, animals, and waste. It can be used to generate electricity, heat, and transportation fuels, as well as to produce chemicals, materials, and other products. Biomass is a promising alternative to fossil fuels, as it can reduce emissions of carbon dioxide and other pollutants while providing a reliable source of energy. There are a number of different types of biomass, including wood and woody biomass, agricultural residues, animal waste, and organic municipal waste. Read on to learn more about biomass and its potential to reduce emissions and provide a sustainable source of energy.
Lakes store huge amounts of methane. In a new study, environmental scientists at the University of Basel offer suggestions for how it can be extracted and used as an energy source in the form of methanol. Discussion about the current climate crisis usually focuses on carbon dioxide (CO2). The greenhouse gas methane is less well known, but although it is much rarer in the atmosphere, its global warming potential is 80 to 100 times greater per unit. More than half the methane caused by human activities comes from oil production and agricultural fertilizers. But the gas is also created by the natural decomposition of biomass by microbes, for example in lakes. In their most recent publication, researchers at the University of Basel in Switzerland outline the potential and theoretical possibilities for using methane from lakes and other freshwater bodies for sustainable energy production. Methane from lakes and water reservoirs makes up about 20% of global natural methane missions. “That would theoretically be enough to meet the world’s energy needs,” says Maciej Bartosiewicz, a postdoc in the Department of Environmental Sciences of the University of Basel. Lakes continuously absorb CO2 from the atmosphere through the growth of phytoplankton. Microbes convert the carbon, fixed by photosynthesis, into methane when they process biomass. That way, carbon bound in the methane remains within the natural cycle during combustion. Fossil fuels could be partially replaced by “natural” renewable methane. Methane gas is already burned in gas-fired power plants for electricity production and used as a fuel in the form of liquid methanol. Lakes as huge energy stores The idea described in the article isn’t completely new: since 2016, methane in Lake Kivu between Rwanda and the Democratic Republic of Congo has been extracted from a depth of 260 meters, cleaned and used for energy supply directly via generators. “Methane occurs in high concentrations in large quantities on the lake bed there,” explains Bartosiewicz. “The methane concentration is about 100 times higher than in ordinary lakes.” Low concentrations made extracting methane from conventional lakes seem too technically difficult until a few years ago. But new microporous membranes made of polymeric materials now allow the gas to be separated from the water much more efficiently. The researchers have made the first concrete proposals in this regard: using a hydrophobic gas-liquid membrane contactor, a methane-containing gas mixture can be separated from water and the methane concentrated. Zeolite minerals are particularly suitable for enrichment, since hydrophobic crystalline substances can adsorb and release gases. Potential positive effects on ecosystems “With our idea, we wanted to start a broad discussion about the potential, feasibility and risks of a technology like this,” says Bartosiewicz. “Until now, no studies have addressed the effects of methane removal on lake ecosystem functioning, but no immediate negative effects can be foreseen with our current understanding.” However, removing excess carbon could even help curb excessive phytoplankton bloom formation and reduce natural greenhouse gas emissions from lakes. More work is needed before any practical implementation of this initial theoretical idea, says Bartosiewicz. But he’s convinced: “This concept could one day make an important contribution to reaching our climate goals.” Image credit: martina bicelli via flickr/creative commons
Researchers at the Paul Scherrer Institute PSI have investigated what measures would be necessary for Switzerland to achieve its zero CO2 emissions goal and how much it might cost per person. In August 2019, the Swiss Federal Council decided on an ambitious target to limit climate change: From the year 2050 onward Switzerland should, on balance, discharge no further greenhouse gas emissions. With this commitment, Switzerland meets the internationally agreed goal of limiting global warming to a maximum of 1.5° C compared to the pre-industrial era. Now a study by the Paul Scherrer Institute, conducted within the Joint Activity "Scenarios and Modelling" of the eight Swiss Competence Centres for Energy Research (SCCER), probes what options for achieving this goal exist in the energy sector. "The goal of achieving net zero CO2 emissions by 2050 requires drastic transformations in the provision and consumption of energy in nearly all areas," concludes Tom Kober, head of the PSI Energy Economics Group and one of the study's main authors. In their analyses, the researchers considered energy-related CO2 emissions as well as CO2 emissions from industrial processes. Today these emissions represent around 80% of the entire Swiss greenhouse gas inventory. Not included in the study's calculations are emissions from international aviation, agriculture – with the exception of emissions from fuel combustion – land use, changes in land use, and forestry, as well as waste – except for emissions from waste incineration. Also, emissions in other countries that are associated with consumption of goods in Switzerland were not a subject of the study. Electricity from photovoltaics must at least double every decade The central conclusions of the study are: Between now and 2050, the installed capacity of photovoltaic systems must at least double every decade. With 26 terawatt hours of production envisioned in 2050, photovoltaic systems will be the second largest generation technology group behind hydropower (approx. 38 terawatt hours in 2050). Furthermore, power plants with cogeneration of heat and power, as well as wind power plants, hydrogen fuel cells, and electricity imports, all contribute to meeting the demand for electricity. In the main scenario for achieving the net zero emissions target, overall electricity generation from power plants and storage facilities in Switzerland will increase by around one-fifth, to 83 terawatt hours in 2050. The study assumes that Swiss nuclear power plants will be decommissioned by 2045. The private car fleet would have to be largely based on electric motors by 2050, meaning that by 2030 every third new car registered would have to be fully electric. In addition, the use of heat pumps in service and living areas would have to be significantly accelerated, so that by 2050 they could cover almost three-quarters of the demand for heating and hot water. At the same time, it would be necessary to achieve significant energy savings through accelerated renovation of residential buildings. If Switzerland wants to achieve the net zero emissions target, a significant increase in electricity consumption must be expected. Thus in 2050, electricity consumption might be around 20 terawatt hours above today's level. A fundamental driver of this growth is the use of electricity to power cars, buses, and trucks, either directly in battery-electric vehicles or indirectly through hydrogen or so-called e-fuels – that is, synthetic fuels, which are produced by means of electricity from hydrogen and CO2. In the stationary sectors, the proliferation of installed heat pumps will increase consumption of electricity. If the necessary efficiency gains in heating and hot water supply are achieved, however, these could compensate for the increased electricity consumption. The study results show that stationary sectors could achieve an almost constant level of electricity consumption. Besides electrical energy, other forms of energy will play a role. For example, long-distance and freight transport as well as energy-intensive industry offer prospects for new hydrogen applications. To produce such low or zero emission hydrogen requires a substantial amount of sustainably generated electricity would be necessary - 9 terawatt hours in 2050. It probably won't work without CO2 capture "If Switzerland wants to achieve the zero emissions target by 2050, then in the future CO2 emissions will have to be reduced every year by an average of one to one and a half million tonnes compared to the previous year," says Evangelos Panos, lead author of the study. "We saw changes in CO2 emissions of this magnitude between 1950 and 1980 – albeit in the opposite direction – back then they increased massively." Though it has limitations, CO2 capture was shown to be necessary to implement the emissions reduction cost-effectively. In some subsectors, it might even be possible to reach a negative balance in terms of CO2 emissions. This would be the case, for example, if biomass is used as an energy source and the CO2 produced during energy generation is not emitted, but rather is captured and stored underground. In the event that this should not be possible in Switzerland – for example due to rejection by the population or because of limited sites for CO2 storage – cross-national transport of captured CO2 and storage in other countries could offer aa alternative. In their study the researchers assume, for the year 2050, a total of almost 9 million tonnes of CO2 would be captured in Switzerland. "More than two-thirds of the emission reductions required for the net zero emissions target can be achieved with technologies that are already commercially available or are in the demonstration phase," Panos explains. The decarbonised energy system of the future is achievable but would require carbon-free energy sources, for example appropriately generated electricity, biofuels and e-fuels, access to the corresponding transport and distribution infrastructures, and the possibility of importing clean fuels and electricity. Costs are hard to estimate With regard to costs, the energy system researchers are cautious. "The costs are very difficult to estimate, because an enormous number of components play a role," Kober says. In the net zero main scenario assumed in the study, the average discounted additional costs of the climate protection scenario compared to the reference scenario with moderate climate protection (40% CO2 reduction in 2050 compared to 1990) in Switzerland would amount to around 330 CHF per person per year (basis 2010) for the period up to 2050. Looking at all of the scenarios examined, one can see a range of average costs between 200 and 860 CHF2010 per person per year, which ultimately reflects different developments in energy technologies, resource availability, and market integration, in the acceptance of technologies, and in preferences regarding supply security. The trend in costs shows, above all, a long-term increase, so comparatively high costs can also be expected after 2050. Image credit: Pranavian via flickr/Creative Commons
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