Monthly Archives: July 2015

Combined heat and power

Combined heat and power (cogeneration) – making the most of energy

Combined heat and power (CHP, also known as cogeneration) is the simultaneous production of power (electricity) and heat from: natural gas (dominantly), coal, oil, biomass, biogas and waste heat (recovery), among other sources. Waste heat can be heat from waste incineration, waste heat from power production and/ or industrial/ commercial/ even residential waste heat. Fuel sources vary from project to project, country to country.

For example, in Iceland, the dominant source for CHP is geothermal. Over half the energy use in Iceland, which has the highest energy use (per capita) of any nation in the world, is geothermal, and much of it CHP. This is energy production for electricity and heated water/ steam for fish farms, pools, etc… and also for geothermal district heating and space heating in general.

 

CHP can be seamlessly integrated in a number of energy technologies. Often, systems are developed exclusively for onsite generation of electrical and/ or mechanical power, in addition to HVAC and water heating. CHP is most often developed with a gas turbine and  a heat recovery unit or a steam boiler with a steam turbine. CHP exists in industrial and commercial buildings, institutional campuses, municipal facilities (district energy systems, wastewater treatment facilities, etc…) and is also implemented for residential properties.

CHP significantly reduces greenhouse gas emissions by 1/3 to ½ or more, and is significantly more efficient, requiring less fuel to produce a given energy output. CHP can produce electricity and thermal energy on site, avoiding the grid and avoiding energy losses that occur via standard transmission and distribution, as well as power outages. The high efficiency inherent in CHP saves consumers money on their utility bills, offering a reliable source of high-quality energy.

From: http://www.greencitytimes.com/

 

Community Solar

Community solar and net metering – pushing renewable energy forward

Community solar refers to energy generated by a solar farm that is invested in by a relatively small portion of the estimated 85% of residential customers who can’t have solar panels on their rooftops or property due to their roofs being physically unsuitable, because the roof/ property is often in shade by another building or trees, because they are renters, or for some other reason. The solar farms are constructed by individual developers, or a group of investors (the construction can also be done by the utlity itself), in select areas that are suitable for community solar, have a demand for the service, and can range from a few dozen panels to thousands. The customer invests in a few or more of the panels, receives credit for the power they consume at a fixed rate (usually fixed) per kilowatt-hour that is then deducted from their utility (electric) bills.

Net metering, on the other hand, is for residential customers who have PV systems on their rooftop/ property that may generate more electricity than the home uses when the sun’s out. The PV systems are connected to the grid via the owner’s service panel and meter. The owner of the PV system is credited when excess energy is generated than is needed for the home, i.e. times when the meter moves “backwards”. The customer then pays the “net” of the meter moving in both directions – forwards to measure power purchased (when the home demand is greater than the power generated by their PV panels), and backwards when power is returned to the grid. The net consumption is then charged on the utility bill.

Both community solar and net metering encourage power consumption in homes by means of solar energy. Both are great ideas for states in the US (where both of these ideas have found some success), and for countries all over the world. Both represent concepts that enable renewable energy to reach more of the public (illustrated more in the case of community solar) and make solar more desirable (highlighted in the case of net metering). Whether the purpose is to spread clean energy or to reap the financial benefits of the solar boom, both community solar and net metering are undeniably positive ideas.

From: http://www.greencitytimes.com/

Gasification Applications Chart

Gasification – syngas from fossil fuels and environmentally friendly versions

The creation of syngas (or synthetic natural gas) is a technology based on coal gasification for the majority of plants, although it can also be based on biomass or other, fossil, fuels. Since it is also usually based on a nonrenewable fossil fuel, and usually involves the emission of greenhouse gasses like CO2, it can’t be described as a “green” technology. However, when coal gasification is used in conjunction with carbon capture and storage (CCS), or a green technology like integrated gasification combined cycle (IGCC), or when syngas is created using biomass, the technology is certainly “greener” than burning a fossil fuel. IGCC is a fairly new technology that uses a gasifier in converting coal and biomass into syngas, and has come to be known as “clean coal”. Syngas plants use coal gasification for the most part, but to make the production of syngas greener, use of IGCC or biomass must be implemented.

Lignite, a brownish type of coal, is most often used as a source in the process of creating syngas. Gasification uses the coal, steam and oxygen to create syngas — mostly hydrogen and carbon monoxide. The syngas can then be burned directly to create energy used to generate electricity or heat homes and businesses, convert the syngas into “substitute natural gas”, or can be used to create products including methanol, nitrogen-based fertilizers and hydrogen for oil refining and transportation fuels. Coal gasification is sometimes called “clean coal” because it can create energy with less harm to the environment than traditional fossil fuel use.

A significantly more environmentally friendly version of gasification, other than coal use, is available in biomass. Biomass gasification uses a feedstock as in agricultural residues (like wheat and straw), energy crops (like switchgrass), forestry residues and urban wood waste (for example, from construction sites).

The leading region in the world for syngas production is Asia/ Australia, in particular China. China mostly uses coal for its syngas production, relying on their vast coal deposits, thus still producing significant quantities of greenhouse gas emissions. China is trying to rely more on domestic sources for gas and less on importing liquefied natural gas. A significant number of gasification plants are found in India, South Korea, Taiwan and Singapore.

The Africa/ Middle East region also produces a significant quantity of syngas, more than Europe. However, production of syngas in Europe uses a wider selection of feedstocks, technologies and products than other regions. The coal-based units primarily utilize IGCC technologies. There are petroleum, natural gas and biomass plants that produce either power or chemicals. A fairly new plant in Swindon, England illustrates the advancements that European nations are making with gasification. Methanization is used to transform gasified biomass into grid-quality syngas, the biosynthetic natural gas then providing power to the grid.

Most syngas production in North America lies within the United States. These plants include: natural gas facilities that primarily produce chemicals, coal and petroleum plants that produce either power, chemicals and fertilizers or syngas, including a couple of IGCC plants. In Canada, gasification is used to produce hydrogen and power to upgrade synthetic crude oil from the tar sands.

From: http://www.greencitytimes.com

Cellulosic biofuel

Cellulosic biofuel – one fuel option

Ethanol is traditionally made from food crops like corn and sugarcane, but it can also be made from cellulosic feedstocks, non-food crops or inedible waste products. Examples of sources for cellulosic biofuel are crop residues, Miscanthus, switch grass, paper pulp, packaging, cardboard, sawdust, wood chips, rice hulls, corn stover and the byproducts of lawn and tree maintenance.

Technically, almost all plants have the lingocelluloses needed to produce ethanol from cellulosic material. Once glucose is freed from the cellulose using enzymes, fermentation produces ethanol, similar to how ethanol is traditionally produced from 1st generation biofuel sources. Lignin is also produced in the process, which can be burned as a carbon-neutral fuel for local processing plants, businesses and perhaps even homes.

There are tons of cellulose containing raw materials that could be used to produce ethanol that are simply thrown away each year in the U.S. alone. Examples of this are over 100 million dry tons of urban wood wastes and forest residues and over 150 million dry tons of corn stover and wheat straw. That material plus just a fraction of the other paper, wood and plant products that could be used to create ethanol instead of garbage would be enough to make the U.S. independent of foreign oil. This theme is true in other parts of the world as well.

Financial concerns stop cellulosic biofuel from really taking off and providing a consistent source of fuel. This type of ethanol production involves an additional step, the breakdown of the raw material into glucose with enzymes, which translates into a higher cost. However, the raw material is abundant, and the reduction of greenhouse gas emissions from cellulosic biofuel can be up to 90% compared to fossil fuel petroleum, significantly greater than those obtained from traditional 1st generation biofuels. Cellulosic raw material can be easily grown in land marginal for actual agriculture or simply be diverted from landfills, in order to make the production of cellulosic biofuel more cost-effective. Cost-effective processes, such as using inexpensive enzymes to break down the cellulose, are being researched and developed as well.

From: http://www.greencitytimes.com

algae farm

Algae Farms – the Future of Biofuel

Most biofuel in the world today is sourced from 1st generation crops like corn, sugarcane, soybean or other crops from traditional sources. In reality, most current biofuel sources are inadequate to meet rising global demands. In addition, much of current biofuel is derived from food products, needed to address hunger from the global food crisis.

One solution to producing biofuel, especially ethanol, without using crops that are usually designated as food, is to use algae. Algae, especially microalgae, production is becoming more and more economically feasible. This is because of its exceptionally rapid growth rate. Algae grow 20–30 times faster than many food crops, contain up to 30 times more fuel potential (in the form of oil) than soybean or even palm oil, and algae farms can be located anywhere.

One great feature of algae that makes it ideal for biofuel production is that up to 60% of its mass is oil. Another is that algae requires CO2 to grow, so it essentially sequesters CO2 from the atmosphere as it grows. Algae reproduce quickly, needing only sunlight and water, are non-toxic and biodegradable. As algae grows, the oil is harvested for fuel while the remaining green mass by-product can be used in fish and oyster farms.

 

Algaculture has proven, based on current algae production technologies, that it can provide future global energy needs while being economically viable and sustainable. Algae production also creates useful co-products, such as bio-fertilizers. If the production of these products is made part of the goal of algae farms, biofuel production from algae will become more economically competitive sooner. Algae offers a great source for a more sustainable transportation fuel, but also offers a range of other benefits and co-products, such as carbon sequestration and fertilizer.

From: http://www.greencitytimes.com

next-gen battery

advanced next-gen batteries for 2015 and the future

New battery chemistries that represent a higher energy capacity are being developed in li-ion batteries. Li-ion batteries that can double the capacity of current batteries, last up to 20 years and charge in minutes, often while cutting costs, are being introduced to the market. A few examples of such new technology are li-ion sulphur, li-ion metal, li-ion silicon, li-ion cobalt oxide, li-ion manganese oxide and li-ion phosphate. Batteries based on li-ion solid-state chemistries could revolutionize battery technology for electric vehicles, grid storage and much more.

Other advanced next-gen battery types have varying degrees of research, and are at different levels of marketability. Li-ion batteries remain the most prominent in today’s market. However, sodium-ion batteries represent a much cheaper, more abundant material that could produce a less expensive battery with similar performance to li-ion.

Vanadium flow batteries have high capacity storage, a long lifespan (up to 20 years), can be idle when solar and wind aren’t producing and then discharge instantly. They have the unique ability to charge and discharge simultaneously and to release large amounts of electricity quickly. As they are inexpensive to scale up, vanadium flow batteries represent an opportunity for reliable, affordable large-scale energy storage.

Lithium-vanadium phosphate batteries are a next generation battery solution which shows promise, as they can extend the range of electric cars to compete with gasoline ones. These batteries not only have greater power than batteries found in the latest electric vehicles (such as lithium-manganese oxide), but also greater safety than the batteries found in cell phones and laptops..In addition, recharging lithium-vanadium batteries is faster than batteries currently used in EV’s.

Unlike vanadium flow batteries, which currently supply a great battery alternative, lithium-air batteries mostly theoretically represent a great battery alternative. Lithium-air batteries could triple the range of electric cars and could give electric cars the same range as gasoline ones. However, whereas vanadium flow batteries can charge and discharge repetitively with no problem, lithium-air batteries have been notoriously difficult to re-charge.

 

New batteries are being made from everything from graphene & silicon, magnesium & zinc, sodium & aluminum, manganese & vanadium – all which show great promise. Advancements in next-gen batteries will help add renewable energy storage to the grid, get used in our cell phones and laptops, and help extend the range of electric cars to compete with gasoline ones.

From: http://www.greencitytimes.com